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 (d8847129d134)

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

/*
 * Copyright 2006 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#include "SkEmbossMask.h"
#include "SkMath.h"

static inline int nonzero_to_one(int x) {
#if 0
    return x != 0;
#else
    return ((unsigned)(x | -x)) >> 31;
#endif
}

static inline int neq_to_one(int x, int max) {
#if 0
    return x != max;
#else
    SkASSERT(x >= 0 && x <= max);
    return ((unsigned)(x - max)) >> 31;
#endif
}

static inline int neq_to_mask(int x, int max) {
#if 0
    return -(x != max);
#else
    SkASSERT(x >= 0 && x <= max);
    return (x - max) >> 31;
#endif
}

static inline unsigned div255(unsigned x) {
    SkASSERT(x <= (255*255));
    return x * ((1 << 24) / 255) >> 24;
}

#define kDelta  32  // small enough to show off angle differences

#include "SkEmbossMask_Table.h"

#if defined(SK_BUILD_FOR_WIN32) && defined(SK_DEBUG)

#include <stdio.h>

void SkEmbossMask_BuildTable() {
    // build it 0..127 x 0..127, so we use 2^15 - 1 in the numerator for our "fixed" table

    FILE* file = ::fopen("SkEmbossMask_Table.h", "w");
    SkASSERT(file);
    ::fprintf(file, "#include \"SkTypes.h\"\n\n");
    ::fprintf(file, "static const U16 gInvSqrtTable[128 * 128] = {\n");
    for (int dx = 0; dx <= 255/2; dx++) {
        for (int dy = 0; dy <= 255/2; dy++) {
            if ((dy & 15) == 0)
                ::fprintf(file, "\t");

            uint16_t value = SkToU16((1 << 15) / SkSqrt32(dx * dx + dy * dy + kDelta*kDelta/4));

            ::fprintf(file, "0x%04X", value);
            if (dx * 128 + dy < 128*128-1) {
                ::fprintf(file, ", ");
            }
            if ((dy & 15) == 15) {
                ::fprintf(file, "\n");
            }
        }
    }
    ::fprintf(file, "};\n#define kDeltaUsedToBuildTable\t%d\n", kDelta);
    ::fclose(file);
}

#endif

void SkEmbossMask::Emboss(SkMask* mask, const SkEmbossMaskFilter::Light& light) {
    SkASSERT(kDelta == kDeltaUsedToBuildTable);

    SkASSERT(mask->fFormat == SkMask::k3D_Format);

    int     specular = light.fSpecular;
    int     ambient = light.fAmbient;
    SkFixed lx = SkScalarToFixed(light.fDirection[0]);
    SkFixed ly = SkScalarToFixed(light.fDirection[1]);
    SkFixed lz = SkScalarToFixed(light.fDirection[2]);
    SkFixed lz_dot_nz = lz * kDelta;
    int     lz_dot8 = lz >> 8;

    size_t      planeSize = mask->computeImageSize();
    uint8_t*    alpha = mask->fImage;
    uint8_t*    multiply = (uint8_t*)alpha + planeSize;
    uint8_t*    additive = multiply + planeSize;

    int rowBytes = mask->fRowBytes;
    int maxy = mask->fBounds.height() - 1;
    int maxx = mask->fBounds.width() - 1;

    int prev_row = 0;
    for (int y = 0; y <= maxy; y++) {
        int next_row = neq_to_mask(y, maxy) & rowBytes;

        for (int x = 0; x <= maxx; x++) {
            if (alpha[x]) {
                int nx = alpha[x + neq_to_one(x, maxx)] - alpha[x - nonzero_to_one(x)];
                int ny = alpha[x + next_row] - alpha[x - prev_row];

                SkFixed numer = lx * nx + ly * ny + lz_dot_nz;
                int     mul = ambient;
                int     add = 0;

                if (numer > 0) {  // preflight when numer/denom will be <= 0
#if 0
                    int denom = SkSqrt32(nx * nx + ny * ny + kDelta*kDelta);
                    SkFixed dot = numer / denom;
                    dot >>= 8;  // now dot is 2^8 instead of 2^16
#else
                    // can use full numer, but then we need to call SkFixedMul, since
                    // numer is 24 bits, and our table is 12 bits

                    // SkFixed dot = SkFixedMul(numer, gTable[]) >> 8
                    SkFixed dot = (unsigned)(numer >> 4) * gInvSqrtTable[(SkAbs32(nx) >> 1 << 7) | (SkAbs32(ny) >> 1)] >> 20;
#endif
                    mul = SkFastMin32(mul + dot, 255);

                    // now for the reflection

                    //  R = 2 (Light * Normal) Normal - Light
                    //  hilite = R * Eye(0, 0, 1)

                    int hilite = (2 * dot - lz_dot8) * lz_dot8 >> 8;
                    if (hilite > 0) {
                        // pin hilite to 255, since our fast math is also a little sloppy
                        hilite = SkClampMax(hilite, 255);

                        // specular is 4.4
                        // would really like to compute the fractional part of this
                        // and then possibly cache a 256 table for a given specular
                        // value in the light, and just pass that in to this function.
                        add = hilite;
                        for (int i = specular >> 4; i > 0; --i) {
                            add = div255(add * hilite);
                        }
                    }
                }
                multiply[x] = SkToU8(mul);
                additive[x] = SkToU8(add);

            //  multiply[x] = 0xFF;
            //  additive[x] = 0;
            //  ((uint8_t*)alpha)[x] = alpha[x] * multiply[x] >> 8;
            }
        }
        alpha += rowBytes;
        multiply += rowBytes;
        additive += rowBytes;
        prev_row = rowBytes;
    }
}