DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (b6d82b1a6b02)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "WebGLFramebuffer.h"

// You know it's going to be fun when these two show up:
#include <algorithm>
#include <iterator>

#include "GLBlitHelper.h"
#include "GLContext.h"
#include "GLScreenBuffer.h"
#include "MozFramebuffer.h"
#include "mozilla/dom/WebGLRenderingContextBinding.h"
#include "nsPrintfCString.h"
#include "WebGLContext.h"
#include "WebGLContextUtils.h"
#include "WebGLExtensions.h"
#include "WebGLRenderbuffer.h"
#include "WebGLTexture.h"

namespace mozilla {

static bool ShouldDeferAttachment(const WebGLContext* const webgl,
                                  const GLenum attachPoint) {
  if (webgl->IsWebGL2()) return false;

  switch (attachPoint) {
    case LOCAL_GL_DEPTH_ATTACHMENT:
    case LOCAL_GL_STENCIL_ATTACHMENT:
    case LOCAL_GL_DEPTH_STENCIL_ATTACHMENT:
      return true;
    default:
      return false;
  }
}

WebGLFBAttachPoint::WebGLFBAttachPoint(const WebGLContext* const webgl,
                                       const GLenum attachmentPoint)
    : mAttachmentPoint(attachmentPoint),
      mDeferAttachment(ShouldDeferAttachment(webgl, mAttachmentPoint)) {}

WebGLFBAttachPoint::~WebGLFBAttachPoint() {
  MOZ_ASSERT(!mRenderbufferPtr);
  MOZ_ASSERT(!mTexturePtr);
}

bool WebGLFBAttachPoint::IsDeleteRequested() const {
  return Texture()
             ? Texture()->IsDeleteRequested()
             : Renderbuffer() ? Renderbuffer()->IsDeleteRequested() : false;
}

void WebGLFBAttachPoint::Clear() { Set(nullptr, {}); }

void WebGLFBAttachPoint::Set(gl::GLContext* const gl,
                             const webgl::FbAttachInfo& toAttach) {
  mRenderbufferPtr = toAttach.rb;
  mTexturePtr = toAttach.tex;
  mTexImageLayer = AssertedCast<uint32_t>(toAttach.zLayer);
  mTexImageZLayerCount = AssertedCast<uint8_t>(toAttach.zLayerCount);
  mTexImageLevel = AssertedCast<uint8_t>(toAttach.mipLevel);
  mIsMultiview = toAttach.isMultiview;

  if (gl && !mDeferAttachment) {
    DoAttachment(gl);
  }
}

const webgl::ImageInfo* WebGLFBAttachPoint::GetImageInfo() const {
  if (mTexturePtr) {
    const auto target = Texture()->Target();
    uint8_t face = 0;
    if (target == LOCAL_GL_TEXTURE_CUBE_MAP) {
      face = Layer() % 6;
    }
    return &mTexturePtr->ImageInfoAtFace(face, mTexImageLevel);
  }
  if (mRenderbufferPtr) return &mRenderbufferPtr->ImageInfo();
  return nullptr;
}

bool WebGLFBAttachPoint::IsComplete(WebGLContext* webgl,
                                    nsCString* const out_info) const {
  MOZ_ASSERT(HasAttachment());

  const auto fnWriteErrorInfo = [&](const char* const text) {
    WebGLContext::EnumName(mAttachmentPoint, out_info);
    out_info->AppendLiteral(": ");
    out_info->AppendASCII(text);
  };

  const auto& imageInfo = *GetImageInfo();
  if (!imageInfo.mWidth || !imageInfo.mHeight) {
    fnWriteErrorInfo("Attachment has no width or height.");
    return false;
  }
  MOZ_ASSERT(imageInfo.IsDefined());

  const auto& tex = Texture();
  if (tex) {
    // ES 3.0 spec, pg 213 has giant blocks of text that bake down to requiring
    // that attached tex images are within the valid mip-levels of the texture.
    // While it draws distinction to only test non-immutable textures, that's
    // because immutable textures are *always* texture-complete. We need to
    // check immutable textures though, because checking completeness is also
    // when we zero invalidated/no-data tex images.
    const auto attachedMipLevel = MipLevel();

    const bool withinValidMipLevels = [&]() {
      const bool ensureInit = false;
      const auto texCompleteness = tex->CalcCompletenessInfo(ensureInit);
      if (!texCompleteness)  // OOM
        return false;
      if (!texCompleteness->levels) return false;

      const auto baseLevel = tex->BaseMipmapLevel();
      const auto maxLevel = baseLevel + texCompleteness->levels - 1;
      return baseLevel <= attachedMipLevel && attachedMipLevel <= maxLevel;
    }();
    if (!withinValidMipLevels) {
      fnWriteErrorInfo("Attached mip level is invalid for texture.");
      return false;
    }

    const auto& levelInfo = tex->ImageInfoAtFace(0, attachedMipLevel);
    const auto faceDepth = levelInfo.mDepth * tex->FaceCount();
    const bool withinValidZLayers = Layer() + ZLayerCount() - 1 < faceDepth;
    if (!withinValidZLayers) {
      fnWriteErrorInfo("Attached z layer is invalid for texture.");
      return false;
    }
  }

  const auto& formatUsage = imageInfo.mFormat;
  if (!formatUsage->IsRenderable()) {
    const auto info = nsPrintfCString(
        "Attachment has an effective format of %s,"
        " which is not renderable.",
        formatUsage->format->name);
    fnWriteErrorInfo(info.BeginReading());
    return false;
  }
  if (!formatUsage->IsExplicitlyRenderable()) {
    webgl->WarnIfImplicit(formatUsage->GetExtensionID());
  }

  const auto format = formatUsage->format;

  bool hasRequiredBits;

  switch (mAttachmentPoint) {
    case LOCAL_GL_DEPTH_ATTACHMENT:
      hasRequiredBits = format->d;
      break;

    case LOCAL_GL_STENCIL_ATTACHMENT:
      hasRequiredBits = format->s;
      break;

    case LOCAL_GL_DEPTH_STENCIL_ATTACHMENT:
      MOZ_ASSERT(!webgl->IsWebGL2());
      hasRequiredBits = (format->d && format->s);
      break;

    default:
      MOZ_ASSERT(mAttachmentPoint >= LOCAL_GL_COLOR_ATTACHMENT0);
      hasRequiredBits = format->IsColorFormat();
      break;
  }

  if (!hasRequiredBits) {
    fnWriteErrorInfo(
        "Attachment's format is missing required color/depth/stencil"
        " bits.");
    return false;
  }

  if (!webgl->IsWebGL2()) {
    bool hasSurplusPlanes = false;

    switch (mAttachmentPoint) {
      case LOCAL_GL_DEPTH_ATTACHMENT:
        hasSurplusPlanes = format->s;
        break;

      case LOCAL_GL_STENCIL_ATTACHMENT:
        hasSurplusPlanes = format->d;
        break;
    }

    if (hasSurplusPlanes) {
      fnWriteErrorInfo(
          "Attachment has depth or stencil bits when it shouldn't.");
      return false;
    }
  }

  return true;
}

void WebGLFBAttachPoint::DoAttachment(gl::GLContext* const gl) const {
  if (Renderbuffer()) {
    Renderbuffer()->DoFramebufferRenderbuffer(mAttachmentPoint);
    return;
  }

  if (!Texture()) {
    MOZ_ASSERT(mAttachmentPoint != LOCAL_GL_DEPTH_STENCIL_ATTACHMENT);
    // WebGL 2 doesn't have a real attachment for this, and WebGL 1 is defered
    // and only DoAttachment if HasAttachment.

    gl->fFramebufferRenderbuffer(LOCAL_GL_FRAMEBUFFER, mAttachmentPoint,
                                 LOCAL_GL_RENDERBUFFER, 0);
    return;
  }

  const auto& texName = Texture()->mGLName;

  switch (Texture()->Target().get()) {
    case LOCAL_GL_TEXTURE_2D:
    case LOCAL_GL_TEXTURE_CUBE_MAP: {
      TexImageTarget imageTarget = LOCAL_GL_TEXTURE_2D;
      if (Texture()->Target() == LOCAL_GL_TEXTURE_CUBE_MAP) {
        imageTarget = LOCAL_GL_TEXTURE_CUBE_MAP_POSITIVE_X + Layer();
      }

      if (mAttachmentPoint == LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
        gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER,
                                  LOCAL_GL_DEPTH_ATTACHMENT, imageTarget.get(),
                                  texName, MipLevel());
        gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER,
                                  LOCAL_GL_STENCIL_ATTACHMENT,
                                  imageTarget.get(), texName, MipLevel());
      } else {
        gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER, mAttachmentPoint,
                                  imageTarget.get(), texName, MipLevel());
      }
      break;
    }

    case LOCAL_GL_TEXTURE_2D_ARRAY:
    case LOCAL_GL_TEXTURE_3D:
      if (ZLayerCount() != 1) {
        gl->fFramebufferTextureMultiview(LOCAL_GL_FRAMEBUFFER, mAttachmentPoint,
                                         texName, MipLevel(), Layer(),
                                         ZLayerCount());
      } else {
        gl->fFramebufferTextureLayer(LOCAL_GL_FRAMEBUFFER, mAttachmentPoint,
                                     texName, MipLevel(), Layer());
      }
      break;
  }
}

JS::Value WebGLFBAttachPoint::GetParameter(WebGLContext* webgl, JSContext* cx,
                                           GLenum target, GLenum attachment,
                                           GLenum pname,
                                           ErrorResult* const out_error) const {
  if (!HasAttachment()) {
    // Divergent between GLES 3 and 2.

    // GLES 2.0.25 p127:
    //   "If the value of FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is NONE, then
    //   querying any other pname will generate INVALID_ENUM."

    // GLES 3.0.4 p240:
    //   "If the value of FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is NONE, no
    //   framebuffer is bound to target. In this case querying pname
    //   FRAMEBUFFER_ATTACHMENT_OBJECT_NAME will return zero, and all other
    //   queries will generate an INVALID_OPERATION error."
    switch (pname) {
      case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE:
        return JS::Int32Value(LOCAL_GL_NONE);

      case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME:
        if (webgl->IsWebGL2()) return JS::NullValue();

        break;

      default:
        break;
    }
    nsCString attachmentName;
    WebGLContext::EnumName(attachment, &attachmentName);
    if (webgl->IsWebGL2()) {
      webgl->ErrorInvalidOperation("No attachment at %s.",
                                   attachmentName.BeginReading());
    } else {
      webgl->ErrorInvalidEnum("No attachment at %s.",
                              attachmentName.BeginReading());
    }
    return JS::NullValue();
  }

  bool isPNameValid = false;
  switch (pname) {
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE:
      return JS::Int32Value(mTexturePtr ? LOCAL_GL_TEXTURE
                                        : LOCAL_GL_RENDERBUFFER);

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME:
      return (mTexturePtr ? webgl->WebGLObjectAsJSValue(cx, mTexturePtr.get(),
                                                        *out_error)
                          : webgl->WebGLObjectAsJSValue(
                                cx, mRenderbufferPtr.get(), *out_error));

      //////

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL:
      if (mTexturePtr) return JS::Int32Value(MipLevel());
      break;

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE:
      if (mTexturePtr) {
        GLenum face = 0;
        if (mTexturePtr->Target() == LOCAL_GL_TEXTURE_CUBE_MAP) {
          face = LOCAL_GL_TEXTURE_CUBE_MAP_POSITIVE_X + Layer();
        }
        return JS::Int32Value(face);
      }
      break;

      //////

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER:
      if (webgl->IsWebGL2()) {
        return JS::Int32Value(AssertedCast<int32_t>(Layer()));
      }
      break;

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_BASE_VIEW_INDEX_OVR:
      if (webgl->IsExtensionEnabled(WebGLExtensionID::OVR_multiview2)) {
        return JS::Int32Value(AssertedCast<int32_t>(Layer()));
      }
      break;

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_NUM_VIEWS_OVR:
      if (webgl->IsExtensionEnabled(WebGLExtensionID::OVR_multiview2)) {
        return JS::Int32Value(ZLayerCount());
      }
      break;

      //////

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE:
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE:
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE:
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE:
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE:
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE:
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE:
      isPNameValid = webgl->IsWebGL2();
      break;

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING:
      isPNameValid = (webgl->IsWebGL2() ||
                      webgl->IsExtensionEnabled(WebGLExtensionID::EXT_sRGB));
      break;
  }

  if (!isPNameValid) {
    webgl->ErrorInvalidEnum("Invalid pname: 0x%04x", pname);
    return JS::NullValue();
  }

  const auto& imageInfo = *GetImageInfo();
  const auto& usage = imageInfo.mFormat;
  if (!usage) {
    if (pname == LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING)
      return JS::NumberValue(LOCAL_GL_LINEAR);

    return JS::NullValue();
  }

  auto format = usage->format;

  GLint ret = 0;
  switch (pname) {
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE:
      ret = format->r;
      break;
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE:
      ret = format->g;
      break;
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE:
      ret = format->b;
      break;
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE:
      ret = format->a;
      break;
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE:
      ret = format->d;
      break;
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE:
      ret = format->s;
      break;

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING:
      ret = (format->isSRGB ? LOCAL_GL_SRGB : LOCAL_GL_LINEAR);
      break;

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE:
      MOZ_ASSERT(attachment != LOCAL_GL_DEPTH_STENCIL_ATTACHMENT);

      if (format->unsizedFormat == webgl::UnsizedFormat::DEPTH_STENCIL) {
        MOZ_ASSERT(attachment == LOCAL_GL_DEPTH_ATTACHMENT ||
                   attachment == LOCAL_GL_STENCIL_ATTACHMENT);

        if (attachment == LOCAL_GL_DEPTH_ATTACHMENT) {
          switch (format->effectiveFormat) {
            case webgl::EffectiveFormat::DEPTH24_STENCIL8:
              format =
                  webgl::GetFormat(webgl::EffectiveFormat::DEPTH_COMPONENT24);
              break;
            case webgl::EffectiveFormat::DEPTH32F_STENCIL8:
              format =
                  webgl::GetFormat(webgl::EffectiveFormat::DEPTH_COMPONENT32F);
              break;
            default:
              MOZ_ASSERT(false, "no matched DS format");
              break;
          }
        } else if (attachment == LOCAL_GL_STENCIL_ATTACHMENT) {
          switch (format->effectiveFormat) {
            case webgl::EffectiveFormat::DEPTH24_STENCIL8:
            case webgl::EffectiveFormat::DEPTH32F_STENCIL8:
              format = webgl::GetFormat(webgl::EffectiveFormat::STENCIL_INDEX8);
              break;
            default:
              MOZ_ASSERT(false, "no matched DS format");
              break;
          }
        }
      }

      switch (format->componentType) {
        case webgl::ComponentType::Int:
          ret = LOCAL_GL_INT;
          break;
        case webgl::ComponentType::UInt:
          ret = LOCAL_GL_UNSIGNED_INT;
          break;
        case webgl::ComponentType::NormInt:
          ret = LOCAL_GL_SIGNED_NORMALIZED;
          break;
        case webgl::ComponentType::NormUInt:
          ret = LOCAL_GL_UNSIGNED_NORMALIZED;
          break;
        case webgl::ComponentType::Float:
          ret = LOCAL_GL_FLOAT;
          break;
      }
      break;

    default:
      MOZ_ASSERT(false, "Missing case.");
      break;
  }

  return JS::Int32Value(ret);
}

////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
// WebGLFramebuffer

WebGLFramebuffer::WebGLFramebuffer(WebGLContext* webgl, GLuint fbo)
    : WebGLRefCountedObject(webgl),
      mGLName(fbo),
      mDepthAttachment(webgl, LOCAL_GL_DEPTH_ATTACHMENT),
      mStencilAttachment(webgl, LOCAL_GL_STENCIL_ATTACHMENT),
      mDepthStencilAttachment(webgl, LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
  mContext->mFramebuffers.insertBack(this);

  mAttachments.push_back(&mDepthAttachment);
  mAttachments.push_back(&mStencilAttachment);

  if (!webgl->IsWebGL2()) {
    // Only WebGL1 has a separate depth+stencil attachment point.
    mAttachments.push_back(&mDepthStencilAttachment);
  }

  size_t i = 0;
  for (auto& cur : mColorAttachments) {
    new (&cur) WebGLFBAttachPoint(webgl, LOCAL_GL_COLOR_ATTACHMENT0 + i);
    i++;

    mAttachments.push_back(&cur);
  }

  mColorDrawBuffers.push_back(&mColorAttachments[0]);
  mColorReadBuffer = &mColorAttachments[0];
}

void WebGLFramebuffer::Delete() {
  InvalidateCaches();

  mDepthAttachment.Clear();
  mStencilAttachment.Clear();
  mDepthStencilAttachment.Clear();

  for (auto& cur : mColorAttachments) {
    cur.Clear();
  }

  mContext->gl->fDeleteFramebuffers(1, &mGLName);

  LinkedListElement<WebGLFramebuffer>::removeFrom(mContext->mFramebuffers);
}

////

Maybe<WebGLFBAttachPoint*> WebGLFramebuffer::GetColorAttachPoint(
    GLenum attachPoint) {
  if (attachPoint == LOCAL_GL_NONE) return Some<WebGLFBAttachPoint*>(nullptr);

  if (attachPoint < LOCAL_GL_COLOR_ATTACHMENT0) return Nothing();

  const size_t colorId = attachPoint - LOCAL_GL_COLOR_ATTACHMENT0;

  MOZ_ASSERT(mContext->mGLMaxColorAttachments <= kMaxColorAttachments);
  if (colorId >= mContext->mGLMaxColorAttachments) return Nothing();

  return Some(&mColorAttachments[colorId]);
}

Maybe<WebGLFBAttachPoint*> WebGLFramebuffer::GetAttachPoint(
    GLenum attachPoint) {
  switch (attachPoint) {
    case LOCAL_GL_DEPTH_STENCIL_ATTACHMENT:
      return Some(&mDepthStencilAttachment);

    case LOCAL_GL_DEPTH_ATTACHMENT:
      return Some(&mDepthAttachment);

    case LOCAL_GL_STENCIL_ATTACHMENT:
      return Some(&mStencilAttachment);

    default:
      return GetColorAttachPoint(attachPoint);
  }
}

void WebGLFramebuffer::DetachTexture(const WebGLTexture* tex) {
  for (const auto& attach : mAttachments) {
    if (attach->Texture() == tex) {
      attach->Clear();
    }
  }
  InvalidateCaches();
}

void WebGLFramebuffer::DetachRenderbuffer(const WebGLRenderbuffer* rb) {
  for (const auto& attach : mAttachments) {
    if (attach->Renderbuffer() == rb) {
      attach->Clear();
    }
  }
  InvalidateCaches();
}

////////////////////////////////////////////////////////////////////////////////
// Completeness

bool WebGLFramebuffer::HasDuplicateAttachments() const {
  std::set<WebGLFBAttachPoint::Ordered> uniqueAttachSet;

  for (const auto& attach : mColorAttachments) {
    if (!attach.HasAttachment()) continue;

    const WebGLFBAttachPoint::Ordered ordered(attach);

    const bool didInsert = uniqueAttachSet.insert(ordered).second;
    if (!didInsert) return true;
  }

  return false;
}

bool WebGLFramebuffer::HasDefinedAttachments() const {
  bool hasAttachments = false;
  for (const auto& attach : mAttachments) {
    hasAttachments |= attach->HasAttachment();
  }
  return hasAttachments;
}

bool WebGLFramebuffer::HasIncompleteAttachments(
    nsCString* const out_info) const {
  bool hasIncomplete = false;
  for (const auto& cur : mAttachments) {
    if (!cur->HasAttachment())
      continue;  // Not defined, so can't count as incomplete.

    hasIncomplete |= !cur->IsComplete(mContext, out_info);
  }
  return hasIncomplete;
}

bool WebGLFramebuffer::AllImageRectsMatch() const {
  MOZ_ASSERT(HasDefinedAttachments());
  DebugOnly<nsCString> fbStatusInfo;
  MOZ_ASSERT(!HasIncompleteAttachments(&fbStatusInfo));

  bool needsInit = true;
  uint32_t width = 0;
  uint32_t height = 0;

  bool hasMismatch = false;
  for (const auto& attach : mAttachments) {
    const auto& imageInfo = attach->GetImageInfo();
    if (!imageInfo) continue;

    const auto& curWidth = imageInfo->mWidth;
    const auto& curHeight = imageInfo->mHeight;

    if (needsInit) {
      needsInit = false;
      width = curWidth;
      height = curHeight;
      continue;
    }

    hasMismatch |= (curWidth != width || curHeight != height);
  }
  return !hasMismatch;
}

bool WebGLFramebuffer::AllImageSamplesMatch() const {
  MOZ_ASSERT(HasDefinedAttachments());
  DebugOnly<nsCString> fbStatusInfo;
  MOZ_ASSERT(!HasIncompleteAttachments(&fbStatusInfo));

  bool needsInit = true;
  uint32_t samples = 0;

  bool hasMismatch = false;
  for (const auto& attach : mAttachments) {
    const auto& imageInfo = attach->GetImageInfo();
    if (!imageInfo) continue;

    const auto& curSamples = imageInfo->mSamples;

    if (needsInit) {
      needsInit = false;
      samples = curSamples;
      continue;
    }

    hasMismatch |= (curSamples != samples);
  };
  return !hasMismatch;
}

FBStatus WebGLFramebuffer::PrecheckFramebufferStatus(
    nsCString* const out_info) const {
  MOZ_ASSERT(mContext->mBoundDrawFramebuffer == this ||
             mContext->mBoundReadFramebuffer == this);

  if (!HasDefinedAttachments())
    return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT;  // No
                                                                // attachments

  if (HasIncompleteAttachments(out_info))
    return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;

  if (!AllImageRectsMatch())
    return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS;  // Inconsistent sizes

  if (!AllImageSamplesMatch())
    return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;  // Inconsistent samples

  if (HasDuplicateAttachments()) return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;

  if (mContext->IsWebGL2()) {
    MOZ_ASSERT(!mDepthStencilAttachment.HasAttachment());
    if (mDepthAttachment.HasAttachment() &&
        mStencilAttachment.HasAttachment()) {
      if (!mDepthAttachment.IsEquivalentForFeedback(mStencilAttachment))
        return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;
    }
  } else {
    const auto depthOrStencilCount =
        int(mDepthAttachment.HasAttachment()) +
        int(mStencilAttachment.HasAttachment()) +
        int(mDepthStencilAttachment.HasAttachment());
    if (depthOrStencilCount > 1) return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;
  }

  {
    const WebGLFBAttachPoint* example = nullptr;
    for (const auto& x : mAttachments) {
      if (!x->HasAttachment()) continue;
      if (!example) {
        example = x;
        continue;
      }
      if (x->ZLayerCount() != example->ZLayerCount()) {
        return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_VIEW_TARGETS_OVR;
      }
    }
  }

  return LOCAL_GL_FRAMEBUFFER_COMPLETE;
}

////////////////////////////////////////
// Validation

bool WebGLFramebuffer::ValidateAndInitAttachments(
    const GLenum incompleteFbError) const {
  MOZ_ASSERT(mContext->mBoundDrawFramebuffer == this ||
             mContext->mBoundReadFramebuffer == this);

  const auto fbStatus = CheckFramebufferStatus();
  if (fbStatus == LOCAL_GL_FRAMEBUFFER_COMPLETE) return true;

  mContext->GenerateError(incompleteFbError, "Framebuffer must be complete.");
  return false;
}

bool WebGLFramebuffer::ValidateClearBufferType(GLenum buffer,
                                               uint32_t drawBuffer,
                                               GLenum funcType) const {
  if (buffer != LOCAL_GL_COLOR) return true;

  const auto& attach = mColorAttachments[drawBuffer];
  const auto& imageInfo = attach.GetImageInfo();
  if (!imageInfo) return true;

  if (!count(mColorDrawBuffers.begin(), mColorDrawBuffers.end(), &attach))
    return true;  // DRAW_BUFFERi set to NONE.

  GLenum attachType;
  switch (imageInfo->mFormat->format->componentType) {
    case webgl::ComponentType::Int:
      attachType = LOCAL_GL_INT;
      break;
    case webgl::ComponentType::UInt:
      attachType = LOCAL_GL_UNSIGNED_INT;
      break;
    default:
      attachType = LOCAL_GL_FLOAT;
      break;
  }

  if (attachType != funcType) {
    mContext->ErrorInvalidOperation(
        "This attachment is of type 0x%04x, but"
        " this function is of type 0x%04x.",
        attachType, funcType);
    return false;
  }

  return true;
}

bool WebGLFramebuffer::ValidateForColorRead(
    const webgl::FormatUsageInfo** const out_format, uint32_t* const out_width,
    uint32_t* const out_height) const {
  if (!mColorReadBuffer) {
    mContext->ErrorInvalidOperation("READ_BUFFER must not be NONE.");
    return false;
  }

  if (mColorReadBuffer->ZLayerCount() > 1) {
    mContext->GenerateError(LOCAL_GL_INVALID_FRAMEBUFFER_OPERATION,
                            "The READ_BUFFER attachment has multiple views.");
    return false;
  }

  const auto& imageInfo = mColorReadBuffer->GetImageInfo();
  if (!imageInfo) {
    mContext->ErrorInvalidOperation(
        "The READ_BUFFER attachment is not defined.");
    return false;
  }

  if (imageInfo->mSamples) {
    mContext->ErrorInvalidOperation(
        "The READ_BUFFER attachment is multisampled.");
    return false;
  }

  *out_format = imageInfo->mFormat;
  *out_width = imageInfo->mWidth;
  *out_height = imageInfo->mHeight;
  return true;
}

////////////////////////////////////////////////////////////////////////////////
// Resolution and caching

void WebGLFramebuffer::DoDeferredAttachments() const {
  if (mContext->IsWebGL2()) return;

  const auto& gl = mContext->gl;
  gl->fFramebufferRenderbuffer(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_DEPTH_ATTACHMENT,
                               LOCAL_GL_RENDERBUFFER, 0);
  gl->fFramebufferRenderbuffer(LOCAL_GL_FRAMEBUFFER,
                               LOCAL_GL_STENCIL_ATTACHMENT,
                               LOCAL_GL_RENDERBUFFER, 0);

  const auto fn = [&](const WebGLFBAttachPoint& attach) {
    MOZ_ASSERT(attach.mDeferAttachment);
    if (attach.HasAttachment()) {
      attach.DoAttachment(gl);
    }
  };
  // Only one of these will have an attachment.
  fn(mDepthAttachment);
  fn(mStencilAttachment);
  fn(mDepthStencilAttachment);
}

void WebGLFramebuffer::ResolveAttachmentData() const {
  // GLES 3.0.5 p188:
  //   The result of clearing integer color buffers with `Clear` is undefined.

  // Two different approaches:
  // On WebGL 2, we have glClearBuffer, and *must* use it for integer buffers,
  // so let's just use it for all the buffers. One WebGL 1, we might not have
  // glClearBuffer,

  // WebGL 1 is easier, because we can just call glClear, possibly with
  // glDrawBuffers.

  const auto& gl = mContext->gl;

  const webgl::ScopedPrepForResourceClear scopedPrep(*mContext);

  if (mContext->IsWebGL2()) {
    const uint32_t uiZeros[4] = {};
    const int32_t iZeros[4] = {};
    const float fZeros[4] = {};
    const float fOne[] = {1.0f};

    for (const auto& cur : mAttachments) {
      const auto& imageInfo = cur->GetImageInfo();
      if (!imageInfo || !imageInfo->mUninitializedSlices)
        continue;  // Nothing attached, or already has data.

      const auto fnClearBuffer = [&]() {
        const auto& format = imageInfo->mFormat->format;
        MOZ_ASSERT(format->estimatedBytesPerPixel <= sizeof(uiZeros));
        MOZ_ASSERT(format->estimatedBytesPerPixel <= sizeof(iZeros));
        MOZ_ASSERT(format->estimatedBytesPerPixel <= sizeof(fZeros));

        switch (cur->mAttachmentPoint) {
          case LOCAL_GL_DEPTH_ATTACHMENT:
            gl->fClearBufferfv(LOCAL_GL_DEPTH, 0, fOne);
            break;
          case LOCAL_GL_STENCIL_ATTACHMENT:
            gl->fClearBufferiv(LOCAL_GL_STENCIL, 0, iZeros);
            break;
          default:
            MOZ_ASSERT(cur->mAttachmentPoint !=
                       LOCAL_GL_DEPTH_STENCIL_ATTACHMENT);
            const uint32_t drawBuffer =
                cur->mAttachmentPoint - LOCAL_GL_COLOR_ATTACHMENT0;
            MOZ_ASSERT(drawBuffer <= 100);
            switch (format->componentType) {
              case webgl::ComponentType::Int:
                gl->fClearBufferiv(LOCAL_GL_COLOR, drawBuffer, iZeros);
                break;
              case webgl::ComponentType::UInt:
                gl->fClearBufferuiv(LOCAL_GL_COLOR, drawBuffer, uiZeros);
                break;
              default:
                gl->fClearBufferfv(LOCAL_GL_COLOR, drawBuffer, fZeros);
                break;
            }
        }
      };

      if (imageInfo->mDepth > 1) {
        const auto& tex = cur->Texture();
        const gl::ScopedFramebuffer scopedFB(gl);
        const gl::ScopedBindFramebuffer scopedBindFB(gl, scopedFB.FB());
        for (const auto z : IntegerRange(imageInfo->mDepth)) {
          if ((*imageInfo->mUninitializedSlices)[z]) {
            gl->fFramebufferTextureLayer(LOCAL_GL_FRAMEBUFFER,
                                         cur->mAttachmentPoint, tex->mGLName,
                                         cur->MipLevel(), z);
            fnClearBuffer();
          }
        }
      } else {
        fnClearBuffer();
      }
      imageInfo->mUninitializedSlices = {};
    }
    return;
  }

  uint32_t clearBits = 0;
  std::vector<GLenum> drawBufferForClear;

  const auto fnGather = [&](const WebGLFBAttachPoint& attach,
                            const uint32_t attachClearBits) {
    const auto& imageInfo = attach.GetImageInfo();
    if (!imageInfo || !imageInfo->mUninitializedSlices) return false;

    clearBits |= attachClearBits;
    imageInfo->mUninitializedSlices = {};  // Just mark it now.
    return true;
  };

  //////

  for (const auto& cur : mColorAttachments) {
    if (fnGather(cur, LOCAL_GL_COLOR_BUFFER_BIT)) {
      const uint32_t id = cur.mAttachmentPoint - LOCAL_GL_COLOR_ATTACHMENT0;
      MOZ_ASSERT(id <= 100);
      drawBufferForClear.resize(id + 1);  // Pads with zeros!
      drawBufferForClear[id] = cur.mAttachmentPoint;
    }
  }

  (void)fnGather(mDepthAttachment, LOCAL_GL_DEPTH_BUFFER_BIT);
  (void)fnGather(mStencilAttachment, LOCAL_GL_STENCIL_BUFFER_BIT);
  (void)fnGather(mDepthStencilAttachment,
                 LOCAL_GL_DEPTH_BUFFER_BIT | LOCAL_GL_STENCIL_BUFFER_BIT);

  //////

  if (!clearBits) return;

  if (gl->IsSupported(gl::GLFeature::draw_buffers)) {
    gl->fDrawBuffers(drawBufferForClear.size(), drawBufferForClear.data());
  }

  gl->fClear(clearBits);

  RefreshDrawBuffers();
}

WebGLFramebuffer::CompletenessInfo::~CompletenessInfo() {
  if (!this->fb) return;
  const auto& fb = *this->fb;
  const auto& webgl = fb.mContext;
  fb.mNumFBStatusInvals++;
  if (fb.mNumFBStatusInvals > webgl->mMaxAcceptableFBStatusInvals) {
    webgl->GeneratePerfWarning(
        "FB was invalidated after being complete %u"
        " times. [webgl.perf.max-acceptable-fb-status-invals]",
        uint32_t(fb.mNumFBStatusInvals));
  }
}

////////////////////////////////////////////////////////////////////////////////
// Entrypoints

FBStatus WebGLFramebuffer::CheckFramebufferStatus() const {
  if (mCompletenessInfo) return LOCAL_GL_FRAMEBUFFER_COMPLETE;

  // Ok, let's try to resolve it!

  nsCString statusInfo;
  FBStatus ret = PrecheckFramebufferStatus(&statusInfo);
  do {
    if (ret != LOCAL_GL_FRAMEBUFFER_COMPLETE) break;

    // Looks good on our end. Let's ask the driver.
    gl::GLContext* const gl = mContext->gl;

    const ScopedFBRebinder autoFB(mContext);
    gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mGLName);

    ////

    DoDeferredAttachments();
    RefreshDrawBuffers();
    RefreshReadBuffer();

    ret = gl->fCheckFramebufferStatus(LOCAL_GL_FRAMEBUFFER);

    ////

    if (ret != LOCAL_GL_FRAMEBUFFER_COMPLETE) {
      const nsPrintfCString text("Bad status according to the driver: 0x%04x",
                                 ret.get());
      statusInfo = text;
      break;
    }

    ResolveAttachmentData();

    // Sweet, let's cache that.
    auto info = CompletenessInfo{this, UINT32_MAX, UINT32_MAX};
    mCompletenessInfo.ResetInvalidators({});
    mCompletenessInfo.AddInvalidator(*this);

    const auto fnIsFloat32 = [](const webgl::FormatInfo& info) {
      if (info.componentType != webgl::ComponentType::Float) return false;
      return info.r == 32;
    };

    for (const auto& cur : mAttachments) {
      const auto& tex = cur->Texture();
      const auto& rb = cur->Renderbuffer();
      if (tex) {
        mCompletenessInfo.AddInvalidator(*tex);
        info.texAttachments.push_back(cur);
      } else if (rb) {
        mCompletenessInfo.AddInvalidator(*rb);
      } else {
        continue;
      }
      const auto& imageInfo = cur->GetImageInfo();
      MOZ_ASSERT(imageInfo);
      info.width = std::min(info.width, imageInfo->mWidth);
      info.height = std::min(info.height, imageInfo->mHeight);
      info.hasFloat32 |= fnIsFloat32(*imageInfo->mFormat->format);
      info.zLayerCount = cur->ZLayerCount();
      info.isMultiview = cur->IsMultiview();
    }
    mCompletenessInfo = Some(std::move(info));
    info.fb = nullptr;  // Don't trigger the invalidation warning.
    return LOCAL_GL_FRAMEBUFFER_COMPLETE;
  } while (false);

  MOZ_ASSERT(ret != LOCAL_GL_FRAMEBUFFER_COMPLETE);
  mContext->GenerateWarning("Framebuffer not complete. (status: 0x%04x) %s",
                            ret.get(), statusInfo.BeginReading());
  return ret;
}

////

void WebGLFramebuffer::RefreshDrawBuffers() const {
  const auto& gl = mContext->gl;
  if (!gl->IsSupported(gl::GLFeature::draw_buffers)) return;

  // Prior to GL4.1, having a no-image FB attachment that's selected by
  // DrawBuffers yields a framebuffer status of
  // FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER. We could workaround this only on
  // affected versions, but it's easier be unconditional.
  std::vector<GLenum> driverBuffers(mContext->mGLMaxDrawBuffers, LOCAL_GL_NONE);
  for (const auto& attach : mColorDrawBuffers) {
    if (attach->HasAttachment()) {
      const uint32_t index =
          attach->mAttachmentPoint - LOCAL_GL_COLOR_ATTACHMENT0;
      driverBuffers[index] = attach->mAttachmentPoint;
    }
  }

  gl->fDrawBuffers(driverBuffers.size(), driverBuffers.data());
}

void WebGLFramebuffer::RefreshReadBuffer() const {
  const auto& gl = mContext->gl;
  if (!gl->IsSupported(gl::GLFeature::read_buffer)) return;

  // Prior to GL4.1, having a no-image FB attachment that's selected by
  // ReadBuffer yields a framebuffer status of
  // FRAMEBUFFER_INCOMPLETE_READ_BUFFER. We could workaround this only on
  // affected versions, but it's easier be unconditional.
  GLenum driverBuffer = LOCAL_GL_NONE;
  if (mColorReadBuffer && mColorReadBuffer->HasAttachment()) {
    driverBuffer = mColorReadBuffer->mAttachmentPoint;
  }

  gl->fReadBuffer(driverBuffer);
}

////

void WebGLFramebuffer::DrawBuffers(const dom::Sequence<GLenum>& buffers) {
  if (buffers.Length() > mContext->mGLMaxDrawBuffers) {
    // "An INVALID_VALUE error is generated if `n` is greater than
    // MAX_DRAW_BUFFERS."
    mContext->ErrorInvalidValue(
        "`buffers` must have a length <="
        " MAX_DRAW_BUFFERS.");
    return;
  }

  std::vector<const WebGLFBAttachPoint*> newColorDrawBuffers;
  newColorDrawBuffers.reserve(buffers.Length());

  for (size_t i = 0; i < buffers.Length(); i++) {
    // "If the GL is bound to a draw framebuffer object, the `i`th buffer listed
    // in bufs must be COLOR_ATTACHMENTi or NONE. Specifying a buffer out of
    // order, BACK, or COLOR_ATTACHMENTm where `m` is greater than or equal to
    // the value of MAX_COLOR_ATTACHMENTS, will generate the error
    // INVALID_OPERATION.

    // WEBGL_draw_buffers:
    // "The value of the MAX_COLOR_ATTACHMENTS_WEBGL parameter must be greater
    // than or equal to that of the MAX_DRAW_BUFFERS_WEBGL parameter." This
    // means that if buffers.Length() isn't larger than MaxDrawBuffers, it won't
    // be larger than MaxColorAttachments.
    const auto& cur = buffers[i];
    if (cur == LOCAL_GL_COLOR_ATTACHMENT0 + i) {
      const auto& attach = mColorAttachments[i];
      newColorDrawBuffers.push_back(&attach);
    } else if (cur != LOCAL_GL_NONE) {
      const bool isColorEnum = (cur >= LOCAL_GL_COLOR_ATTACHMENT0 &&
                                cur < mContext->LastColorAttachmentEnum());
      if (cur != LOCAL_GL_BACK && !isColorEnum) {
        mContext->ErrorInvalidEnum("Unexpected enum in buffers.");
        return;
      }

      mContext->ErrorInvalidOperation(
          "`buffers[i]` must be NONE or"
          " COLOR_ATTACHMENTi.");
      return;
    }
  }

  ////

  mColorDrawBuffers.swap(newColorDrawBuffers);
  RefreshDrawBuffers();  // Calls glDrawBuffers.
}

void WebGLFramebuffer::ReadBuffer(GLenum attachPoint) {
  const auto& maybeAttach = GetColorAttachPoint(attachPoint);
  if (!maybeAttach) {
    const char text[] =
        "`mode` must be a COLOR_ATTACHMENTi, for 0 <= i <"
        " MAX_DRAW_BUFFERS.";
    if (attachPoint == LOCAL_GL_BACK) {
      mContext->ErrorInvalidOperation(text);
    } else {
      mContext->ErrorInvalidEnum(text);
    }
    return;
  }
  const auto& attach = maybeAttach.value();  // Might be nullptr.

  ////

  mColorReadBuffer = attach;
  RefreshReadBuffer();  // Calls glReadBuffer.
}

////

void WebGLFramebuffer::FramebufferAttach(const GLenum attachEnum,
                                         const webgl::FbAttachInfo& toAttach) {
  MOZ_ASSERT(mContext->mBoundDrawFramebuffer == this ||
             mContext->mBoundReadFramebuffer == this);

  // `attachment`
  const auto maybeAttach = GetAttachPoint(attachEnum);
  if (!maybeAttach || !maybeAttach.value()) {
    mContext->ErrorInvalidEnum("Bad `attachment`: 0x%x.", attachEnum);
    return;
  }
  const auto& attach = maybeAttach.value();

  const auto& gl = mContext->gl;
  gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mGLName);
  if (mContext->IsWebGL2() && attachEnum == LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
    mDepthAttachment.Set(gl, toAttach);
    mStencilAttachment.Set(gl, toAttach);
  } else {
    attach->Set(gl, toAttach);
  }
  InvalidateCaches();
}

JS::Value WebGLFramebuffer::GetAttachmentParameter(
    JSContext* cx, GLenum target, GLenum attachEnum, GLenum pname,
    ErrorResult* const out_error) {
  const auto maybeAttach = GetAttachPoint(attachEnum);
  if (!maybeAttach || attachEnum == LOCAL_GL_NONE) {
    mContext->ErrorInvalidEnum(
        "Can only query COLOR_ATTACHMENTi,"
        " DEPTH_ATTACHMENT, DEPTH_STENCIL_ATTACHMENT, or"
        " STENCIL_ATTACHMENT for a framebuffer.");
    return JS::NullValue();
  }
  auto attach = maybeAttach.value();

  if (mContext->IsWebGL2() && attachEnum == LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
    // There are a couple special rules for this one.

    if (pname == LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE) {
      mContext->ErrorInvalidOperation(
          "Querying"
          " FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE"
          " against DEPTH_STENCIL_ATTACHMENT is an"
          " error.");
      return JS::NullValue();
    }

    if (mDepthAttachment.Renderbuffer() != mStencilAttachment.Renderbuffer() ||
        mDepthAttachment.Texture() != mStencilAttachment.Texture()) {
      mContext->ErrorInvalidOperation(
          "DEPTH_ATTACHMENT and STENCIL_ATTACHMENT"
          " have different objects bound.");
      return JS::NullValue();
    }

    attach = &mDepthAttachment;
  }

  return attach->GetParameter(mContext, cx, target, attachEnum, pname,
                              out_error);
}

////////////////////

static void GetBackbufferFormats(const WebGLContext* webgl,
                                 const webgl::FormatInfo** const out_color,
                                 const webgl::FormatInfo** const out_depth,
                                 const webgl::FormatInfo** const out_stencil) {
  const auto& options = webgl->Options();

  const auto effFormat = (options.alpha ? webgl::EffectiveFormat::RGBA8
                                        : webgl::EffectiveFormat::RGB8);
  *out_color = webgl::GetFormat(effFormat);

  *out_depth = nullptr;
  *out_stencil = nullptr;
  if (options.depth && options.stencil) {
    *out_depth = webgl::GetFormat(webgl::EffectiveFormat::DEPTH24_STENCIL8);
    *out_stencil = *out_depth;
  } else {
    if (options.depth) {
      *out_depth = webgl::GetFormat(webgl::EffectiveFormat::DEPTH_COMPONENT16);
    }
    if (options.stencil) {
      *out_stencil = webgl::GetFormat(webgl::EffectiveFormat::STENCIL_INDEX8);
    }
  }
}

/*static*/
void WebGLFramebuffer::BlitFramebuffer(WebGLContext* webgl, GLint srcX0,
                                       GLint srcY0, GLint srcX1, GLint srcY1,
                                       GLint dstX0, GLint dstY0, GLint dstX1,
                                       GLint dstY1, GLbitfield mask,
                                       GLenum filter) {
  const GLbitfield depthAndStencilBits =
      LOCAL_GL_DEPTH_BUFFER_BIT | LOCAL_GL_STENCIL_BUFFER_BIT;
  if (bool(mask & depthAndStencilBits) && filter == LOCAL_GL_LINEAR) {
    webgl->ErrorInvalidOperation(
        "DEPTH_BUFFER_BIT and STENCIL_BUFFER_BIT can"
        " only be used with NEAREST filtering.");
    return;
  }

  const auto& srcFB = webgl->mBoundReadFramebuffer;
  const auto& dstFB = webgl->mBoundDrawFramebuffer;

  ////
  // Collect data

  const auto fnGetFormat =
      [](const WebGLFBAttachPoint& cur,
         bool* const out_hasSamples) -> const webgl::FormatInfo* {
    const auto& imageInfo = cur.GetImageInfo();
    if (!imageInfo) return nullptr;  // No attachment.
    *out_hasSamples = bool(imageInfo->mSamples);
    return imageInfo->mFormat->format;
  };

  bool srcHasSamples = false;
  bool srcIsFilterable = true;
  const webgl::FormatInfo* srcColorFormat;
  const webgl::FormatInfo* srcDepthFormat;
  const webgl::FormatInfo* srcStencilFormat;
  gfx::IntSize srcSize;

  if (srcFB) {
    const auto& info = *srcFB->GetCompletenessInfo();
    if (info.zLayerCount != 1) {
      webgl->GenerateError(LOCAL_GL_INVALID_FRAMEBUFFER_OPERATION,
                           "Source framebuffer cannot have multiple views.");
      return;
    }
    srcColorFormat = nullptr;
    if (srcFB->mColorReadBuffer) {
      const auto& imageInfo = srcFB->mColorReadBuffer->GetImageInfo();
      if (imageInfo) {
        srcIsFilterable &= imageInfo->mFormat->isFilterable;
      }
      srcColorFormat = fnGetFormat(*(srcFB->mColorReadBuffer), &srcHasSamples);
    }
    srcDepthFormat = fnGetFormat(srcFB->DepthAttachment(), &srcHasSamples);
    srcStencilFormat = fnGetFormat(srcFB->StencilAttachment(), &srcHasSamples);
    MOZ_ASSERT(!srcFB->DepthStencilAttachment().HasAttachment());
    srcSize = {info.width, info.height};
  } else {
    srcHasSamples = false;  // Always false.

    GetBackbufferFormats(webgl, &srcColorFormat, &srcDepthFormat,
                         &srcStencilFormat);
    srcSize = webgl->DrawingBufferSize();
  }

  ////

  bool dstHasSamples = false;
  const webgl::FormatInfo* dstDepthFormat;
  const webgl::FormatInfo* dstStencilFormat;
  bool dstHasColor = false;
  bool colorFormatsMatch = true;
  bool colorTypesMatch = true;
  bool colorSrgbMatches = true;
  gfx::IntSize dstSize;

  const auto fnCheckColorFormat = [&](const webgl::FormatInfo* dstFormat) {
    MOZ_ASSERT(dstFormat->r || dstFormat->g || dstFormat->b || dstFormat->a);
    dstHasColor = true;
    colorFormatsMatch &= (dstFormat == srcColorFormat);
    colorTypesMatch &=
        srcColorFormat && (dstFormat->baseType == srcColorFormat->baseType);
    colorSrgbMatches &=
        srcColorFormat && (dstFormat->isSRGB == srcColorFormat->isSRGB);
  };

  if (dstFB) {
    for (const auto& cur : dstFB->mColorDrawBuffers) {
      const auto& format = fnGetFormat(*cur, &dstHasSamples);
      if (!format) continue;

      fnCheckColorFormat(format);
    }

    dstDepthFormat = fnGetFormat(dstFB->DepthAttachment(), &dstHasSamples);
    dstStencilFormat = fnGetFormat(dstFB->StencilAttachment(), &dstHasSamples);
    MOZ_ASSERT(!dstFB->DepthStencilAttachment().HasAttachment());

    const auto& info = *dstFB->GetCompletenessInfo();
    dstSize = {info.width, info.height};
  } else {
    dstHasSamples = webgl->Options().antialias;

    const webgl::FormatInfo* dstColorFormat;
    GetBackbufferFormats(webgl, &dstColorFormat, &dstDepthFormat,
                         &dstStencilFormat);

    fnCheckColorFormat(dstColorFormat);

    dstSize = webgl->DrawingBufferSize();
  }

  ////
  // Clear unused buffer bits

  if (mask & LOCAL_GL_COLOR_BUFFER_BIT && !srcColorFormat && !dstHasColor) {
    mask ^= LOCAL_GL_COLOR_BUFFER_BIT;
  }

  if (mask & LOCAL_GL_DEPTH_BUFFER_BIT && !srcDepthFormat && !dstDepthFormat) {
    mask ^= LOCAL_GL_DEPTH_BUFFER_BIT;
  }

  if (mask & LOCAL_GL_STENCIL_BUFFER_BIT && !srcStencilFormat &&
      !dstStencilFormat) {
    mask ^= LOCAL_GL_STENCIL_BUFFER_BIT;
  }

  ////
  // Validation

  if (dstHasSamples) {
    webgl->ErrorInvalidOperation(
        "DRAW_FRAMEBUFFER may not have multiple"
        " samples.");
    return;
  }

  bool requireFilterable = (filter == LOCAL_GL_LINEAR);
  if (srcHasSamples) {
    requireFilterable = false;  // It picks one.

    if (mask & LOCAL_GL_COLOR_BUFFER_BIT && dstHasColor && !colorFormatsMatch) {
      webgl->ErrorInvalidOperation(
          "Color buffer formats must match if"
          " selected, when reading from a multisampled"
          " source.");
      return;
    }

    if (dstX0 != srcX0 || dstX1 != srcX1 || dstY0 != srcY0 || dstY1 != srcY1) {
      webgl->ErrorInvalidOperation(
          "If the source is multisampled, then the"
          " source and dest regions must match exactly.");
      return;
    }
  }

  // -

  if (mask & LOCAL_GL_COLOR_BUFFER_BIT) {
    if (requireFilterable && !srcIsFilterable) {
      webgl->ErrorInvalidOperation(
          "`filter` is LINEAR and READ_BUFFER"
          " contains integer data.");
      return;
    }

    if (!colorTypesMatch) {
      webgl->ErrorInvalidOperation(
          "Color component types (float/uint/"
          "int) must match.");
      return;
    }
  }

  /* GLES 3.0.4, p199:
   *   Calling BlitFramebuffer will result in an INVALID_OPERATION error if
   *   mask includes DEPTH_BUFFER_BIT or STENCIL_BUFFER_BIT, and the source
   *   and destination depth and stencil buffer formats do not match.
   *
   * jgilbert: The wording is such that if only DEPTH_BUFFER_BIT is specified,
   * the stencil formats must match. This seems wrong. It could be a spec bug,
   * or I could be missing an interaction in one of the earlier paragraphs.
   */
  if (mask & LOCAL_GL_DEPTH_BUFFER_BIT && dstDepthFormat &&
      dstDepthFormat != srcDepthFormat) {
    webgl->ErrorInvalidOperation(
        "Depth buffer formats must match if selected.");
    return;
  }

  if (mask & LOCAL_GL_STENCIL_BUFFER_BIT && dstStencilFormat &&
      dstStencilFormat != srcStencilFormat) {
    webgl->ErrorInvalidOperation(
        "Stencil buffer formats must match if selected.");
    return;
  }

  ////
  // Check for feedback

  if (srcFB && dstFB) {
    const WebGLFBAttachPoint* feedback = nullptr;

    if (mask & LOCAL_GL_COLOR_BUFFER_BIT) {
      MOZ_ASSERT(srcFB->mColorReadBuffer->HasAttachment());
      for (const auto& cur : dstFB->mColorDrawBuffers) {
        if (srcFB->mColorReadBuffer->IsEquivalentForFeedback(*cur)) {
          feedback = cur;
          break;
        }
      }
    }

    if (mask & LOCAL_GL_DEPTH_BUFFER_BIT &&
        srcFB->DepthAttachment().IsEquivalentForFeedback(
            dstFB->DepthAttachment())) {
      feedback = &dstFB->DepthAttachment();
    }

    if (mask & LOCAL_GL_STENCIL_BUFFER_BIT &&
        srcFB->StencilAttachment().IsEquivalentForFeedback(
            dstFB->StencilAttachment())) {
      feedback = &dstFB->StencilAttachment();
    }

    if (feedback) {
      webgl->ErrorInvalidOperation(
          "Feedback detected into DRAW_FRAMEBUFFER's"
          " 0x%04x attachment.",
          feedback->mAttachmentPoint);
      return;
    }
  } else if (!srcFB && !dstFB) {
    webgl->ErrorInvalidOperation("Feedback with default framebuffer.");
    return;
  }

  // -

  const auto& gl = webgl->gl;
  const ScopedDrawCallWrapper wrapper(*webgl);
  gl->fBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1,
                       mask, filter);

  // -

  if (mask & LOCAL_GL_COLOR_BUFFER_BIT && !colorSrgbMatches && !gl->IsGLES() &&
      gl->Version() < 440) {
    // Mostly for Mac.
    // Remember, we have to filter in the *linear* format blit.

    // src -Blit-> fbB -DrawBlit-> fbC -Blit-> dst

    const auto fbB = gl::MozFramebuffer::Create(gl, {1, 1}, 0, false);
    const auto fbC = gl::MozFramebuffer::Create(gl, {1, 1}, 0, false);

    // -

    auto sizeBC = srcSize;
    GLenum formatC = LOCAL_GL_RGBA8;
    if (srcColorFormat->isSRGB) {
      // srgb -> linear
    } else {
      // linear -> srgb
      sizeBC = dstSize;
      formatC = LOCAL_GL_SRGB8_ALPHA8;
    }

    const auto fnSetTex = [&](const gl::MozFramebuffer& fb,
                              const GLenum format) {
      const gl::ScopedBindTexture bindTex(gl, fb.ColorTex());
      gl->fTexStorage2D(LOCAL_GL_TEXTURE_2D, 1, format, sizeBC.width,
                        sizeBC.height);
    };
    fnSetTex(*fbB, srcColorFormat->sizedFormat);
    fnSetTex(*fbC, formatC);

    // -

    {
      const gl::ScopedBindFramebuffer bindFb(gl);
      gl->fBindFramebuffer(LOCAL_GL_DRAW_FRAMEBUFFER, fbB->mFB);

      if (srcColorFormat->isSRGB) {
        // srgb -> linear
        gl->fBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, srcX0, srcY0, srcX1,
                             srcY1, LOCAL_GL_COLOR_BUFFER_BIT,
                             LOCAL_GL_NEAREST);
      } else {
        // linear -> srgb
        gl->fBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1,
                             dstY1, LOCAL_GL_COLOR_BUFFER_BIT, filter);
      }

      const auto& blitHelper = *gl->BlitHelper();
      gl->fBindFramebuffer(LOCAL_GL_DRAW_FRAMEBUFFER, fbC->mFB);
      blitHelper.DrawBlitTextureToFramebuffer(fbB->ColorTex(), sizeBC, sizeBC);
    }

    {
      const gl::ScopedBindFramebuffer bindFb(gl);
      gl->fBindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER, fbC->mFB);

      if (srcColorFormat->isSRGB) {
        // srgb -> linear
        gl->fBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1,
                             dstY1, LOCAL_GL_COLOR_BUFFER_BIT, filter);
      } else {
        // linear -> srgb
        gl->fBlitFramebuffer(dstX0, dstY0, dstX1, dstY1, dstX0, dstY0, dstX1,
                             dstY1, LOCAL_GL_COLOR_BUFFER_BIT,
                             LOCAL_GL_NEAREST);
      }
    }
  }

  // -
  // glBlitFramebuffer ignores glColorMask!

  if (!webgl->mBoundDrawFramebuffer && webgl->mNeedsFakeNoAlpha) {
    if (!webgl->mScissorTestEnabled) {
      gl->fEnable(LOCAL_GL_SCISSOR_TEST);
    }
    if (webgl->mRasterizerDiscardEnabled) {
      gl->fDisable(LOCAL_GL_RASTERIZER_DISCARD);
    }
    const WebGLContext::ScissorRect dstRect = {
        std::min(dstX0, dstX1), std::min(dstY0, dstY1), abs(dstX1 - dstX0),
        abs(dstY1 - dstY0)};
    dstRect.Apply(*gl);
    gl->fClearColor(0, 0, 0, 1);

    webgl->DoColorMask(0x8);
    gl->fClear(LOCAL_GL_COLOR_BUFFER_BIT);

    if (!webgl->mScissorTestEnabled) {
      gl->fDisable(LOCAL_GL_SCISSOR_TEST);
    }
    if (webgl->mRasterizerDiscardEnabled) {
      gl->fEnable(LOCAL_GL_RASTERIZER_DISCARD);
    }
    webgl->mScissorRect.Apply(*gl);
    gl->fClearColor(webgl->mColorClearValue[0], webgl->mColorClearValue[1],
                    webgl->mColorClearValue[2], webgl->mColorClearValue[3]);
  }
}

////////////////////////////////////////////////////////////////////////////////
// Goop.

JSObject* WebGLFramebuffer::WrapObject(JSContext* cx,
                                       JS::Handle<JSObject*> givenProto) {
  return dom::WebGLFramebuffer_Binding::Wrap(cx, this, givenProto);
}

inline void ImplCycleCollectionUnlink(mozilla::WebGLFBAttachPoint& field) {
  field.Unlink();
}

inline void ImplCycleCollectionTraverse(
    nsCycleCollectionTraversalCallback& callback,
    const mozilla::WebGLFBAttachPoint& field, const char* name,
    uint32_t flags = 0) {
  CycleCollectionNoteChild(callback, field.Texture(), name, flags);
  CycleCollectionNoteChild(callback, field.Renderbuffer(), name, flags);
}

template <typename C>
inline void ImplCycleCollectionUnlink(C& field) {
  for (auto& cur : field) {
    cur.Unlink();
  }
}

template <typename C>
inline void ImplCycleCollectionTraverse(
    nsCycleCollectionTraversalCallback& callback, const C& field,
    const char* name, uint32_t flags = 0) {
  for (auto& cur : field) {
    ImplCycleCollectionTraverse(callback, cur, name, flags);
  }
}

NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(WebGLFramebuffer, mDepthAttachment,
                                      mStencilAttachment,
                                      mDepthStencilAttachment,
                                      mColorAttachments)

NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(WebGLFramebuffer, AddRef)
NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(WebGLFramebuffer, Release)

}  // namespace mozilla