1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/effects/SkEmbossMask.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,163 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2006 The Android Open Source Project
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +
1.12 +
1.13 +#include "SkEmbossMask.h"
1.14 +#include "SkMath.h"
1.15 +
1.16 +static inline int nonzero_to_one(int x) {
1.17 +#if 0
1.18 + return x != 0;
1.19 +#else
1.20 + return ((unsigned)(x | -x)) >> 31;
1.21 +#endif
1.22 +}
1.23 +
1.24 +static inline int neq_to_one(int x, int max) {
1.25 +#if 0
1.26 + return x != max;
1.27 +#else
1.28 + SkASSERT(x >= 0 && x <= max);
1.29 + return ((unsigned)(x - max)) >> 31;
1.30 +#endif
1.31 +}
1.32 +
1.33 +static inline int neq_to_mask(int x, int max) {
1.34 +#if 0
1.35 + return -(x != max);
1.36 +#else
1.37 + SkASSERT(x >= 0 && x <= max);
1.38 + return (x - max) >> 31;
1.39 +#endif
1.40 +}
1.41 +
1.42 +static inline unsigned div255(unsigned x) {
1.43 + SkASSERT(x <= (255*255));
1.44 + return x * ((1 << 24) / 255) >> 24;
1.45 +}
1.46 +
1.47 +#define kDelta 32 // small enough to show off angle differences
1.48 +
1.49 +#include "SkEmbossMask_Table.h"
1.50 +
1.51 +#if defined(SK_BUILD_FOR_WIN32) && defined(SK_DEBUG)
1.52 +
1.53 +#include <stdio.h>
1.54 +
1.55 +void SkEmbossMask_BuildTable() {
1.56 + // build it 0..127 x 0..127, so we use 2^15 - 1 in the numerator for our "fixed" table
1.57 +
1.58 + FILE* file = ::fopen("SkEmbossMask_Table.h", "w");
1.59 + SkASSERT(file);
1.60 + ::fprintf(file, "#include \"SkTypes.h\"\n\n");
1.61 + ::fprintf(file, "static const U16 gInvSqrtTable[128 * 128] = {\n");
1.62 + for (int dx = 0; dx <= 255/2; dx++) {
1.63 + for (int dy = 0; dy <= 255/2; dy++) {
1.64 + if ((dy & 15) == 0)
1.65 + ::fprintf(file, "\t");
1.66 +
1.67 + uint16_t value = SkToU16((1 << 15) / SkSqrt32(dx * dx + dy * dy + kDelta*kDelta/4));
1.68 +
1.69 + ::fprintf(file, "0x%04X", value);
1.70 + if (dx * 128 + dy < 128*128-1) {
1.71 + ::fprintf(file, ", ");
1.72 + }
1.73 + if ((dy & 15) == 15) {
1.74 + ::fprintf(file, "\n");
1.75 + }
1.76 + }
1.77 + }
1.78 + ::fprintf(file, "};\n#define kDeltaUsedToBuildTable\t%d\n", kDelta);
1.79 + ::fclose(file);
1.80 +}
1.81 +
1.82 +#endif
1.83 +
1.84 +void SkEmbossMask::Emboss(SkMask* mask, const SkEmbossMaskFilter::Light& light) {
1.85 + SkASSERT(kDelta == kDeltaUsedToBuildTable);
1.86 +
1.87 + SkASSERT(mask->fFormat == SkMask::k3D_Format);
1.88 +
1.89 + int specular = light.fSpecular;
1.90 + int ambient = light.fAmbient;
1.91 + SkFixed lx = SkScalarToFixed(light.fDirection[0]);
1.92 + SkFixed ly = SkScalarToFixed(light.fDirection[1]);
1.93 + SkFixed lz = SkScalarToFixed(light.fDirection[2]);
1.94 + SkFixed lz_dot_nz = lz * kDelta;
1.95 + int lz_dot8 = lz >> 8;
1.96 +
1.97 + size_t planeSize = mask->computeImageSize();
1.98 + uint8_t* alpha = mask->fImage;
1.99 + uint8_t* multiply = (uint8_t*)alpha + planeSize;
1.100 + uint8_t* additive = multiply + planeSize;
1.101 +
1.102 + int rowBytes = mask->fRowBytes;
1.103 + int maxy = mask->fBounds.height() - 1;
1.104 + int maxx = mask->fBounds.width() - 1;
1.105 +
1.106 + int prev_row = 0;
1.107 + for (int y = 0; y <= maxy; y++) {
1.108 + int next_row = neq_to_mask(y, maxy) & rowBytes;
1.109 +
1.110 + for (int x = 0; x <= maxx; x++) {
1.111 + if (alpha[x]) {
1.112 + int nx = alpha[x + neq_to_one(x, maxx)] - alpha[x - nonzero_to_one(x)];
1.113 + int ny = alpha[x + next_row] - alpha[x - prev_row];
1.114 +
1.115 + SkFixed numer = lx * nx + ly * ny + lz_dot_nz;
1.116 + int mul = ambient;
1.117 + int add = 0;
1.118 +
1.119 + if (numer > 0) { // preflight when numer/denom will be <= 0
1.120 +#if 0
1.121 + int denom = SkSqrt32(nx * nx + ny * ny + kDelta*kDelta);
1.122 + SkFixed dot = numer / denom;
1.123 + dot >>= 8; // now dot is 2^8 instead of 2^16
1.124 +#else
1.125 + // can use full numer, but then we need to call SkFixedMul, since
1.126 + // numer is 24 bits, and our table is 12 bits
1.127 +
1.128 + // SkFixed dot = SkFixedMul(numer, gTable[]) >> 8
1.129 + SkFixed dot = (unsigned)(numer >> 4) * gInvSqrtTable[(SkAbs32(nx) >> 1 << 7) | (SkAbs32(ny) >> 1)] >> 20;
1.130 +#endif
1.131 + mul = SkFastMin32(mul + dot, 255);
1.132 +
1.133 + // now for the reflection
1.134 +
1.135 + // R = 2 (Light * Normal) Normal - Light
1.136 + // hilite = R * Eye(0, 0, 1)
1.137 +
1.138 + int hilite = (2 * dot - lz_dot8) * lz_dot8 >> 8;
1.139 + if (hilite > 0) {
1.140 + // pin hilite to 255, since our fast math is also a little sloppy
1.141 + hilite = SkClampMax(hilite, 255);
1.142 +
1.143 + // specular is 4.4
1.144 + // would really like to compute the fractional part of this
1.145 + // and then possibly cache a 256 table for a given specular
1.146 + // value in the light, and just pass that in to this function.
1.147 + add = hilite;
1.148 + for (int i = specular >> 4; i > 0; --i) {
1.149 + add = div255(add * hilite);
1.150 + }
1.151 + }
1.152 + }
1.153 + multiply[x] = SkToU8(mul);
1.154 + additive[x] = SkToU8(add);
1.155 +
1.156 + // multiply[x] = 0xFF;
1.157 + // additive[x] = 0;
1.158 + // ((uint8_t*)alpha)[x] = alpha[x] * multiply[x] >> 8;
1.159 + }
1.160 + }
1.161 + alpha += rowBytes;
1.162 + multiply += rowBytes;
1.163 + additive += rowBytes;
1.164 + prev_row = rowBytes;
1.165 + }
1.166 +}
