1 2 /* 3 * Copyright 2006 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #include "SkEmbossMask.h" 11 #include "SkMath.h" 12 13 static inline int nonzero_to_one(int x) { 14 #if 0 15 return x != 0; 16 #else 17 return ((unsigned)(x | -x)) >> 31; 18 #endif 19 } 20 21 static inline int neq_to_one(int x, int max) { 22 #if 0 23 return x != max; 24 #else 25 SkASSERT(x >= 0 && x <= max); 26 return ((unsigned)(x - max)) >> 31; 27 #endif 28 } 29 30 static inline int neq_to_mask(int x, int max) { 31 #if 0 32 return -(x != max); 33 #else 34 SkASSERT(x >= 0 && x <= max); 35 return (x - max) >> 31; 36 #endif 37 } 38 39 static inline unsigned div255(unsigned x) { 40 SkASSERT(x <= (255*255)); 41 return x * ((1 << 24) / 255) >> 24; 42 } 43 44 #define kDelta 32 // small enough to show off angle differences 45 46 #include "SkEmbossMask_Table.h" 47 48 #if defined(SK_BUILD_FOR_WIN32) && defined(SK_DEBUG) 49 50 #include <stdio.h> 51 52 void SkEmbossMask_BuildTable() { 53 // build it 0..127 x 0..127, so we use 2^15 - 1 in the numerator for our "fixed" table 54 55 FILE* file = ::fopen("SkEmbossMask_Table.h", "w"); 56 SkASSERT(file); 57 ::fprintf(file, "#include \"SkTypes.h\"\n\n"); 58 ::fprintf(file, "static const U16 gInvSqrtTable[128 * 128] = {\n"); 59 for (int dx = 0; dx <= 255/2; dx++) { 60 for (int dy = 0; dy <= 255/2; dy++) { 61 if ((dy & 15) == 0) 62 ::fprintf(file, "\t"); 63 64 uint16_t value = SkToU16((1 << 15) / SkSqrt32(dx * dx + dy * dy + kDelta*kDelta/4)); 65 66 ::fprintf(file, "0x%04X", value); 67 if (dx * 128 + dy < 128*128-1) { 68 ::fprintf(file, ", "); 69 } 70 if ((dy & 15) == 15) { 71 ::fprintf(file, "\n"); 72 } 73 } 74 } 75 ::fprintf(file, "};\n#define kDeltaUsedToBuildTable\t%d\n", kDelta); 76 ::fclose(file); 77 } 78 79 #endif 80 81 void SkEmbossMask::Emboss(SkMask* mask, const SkEmbossMaskFilter::Light& light) { 82 SkASSERT(kDelta == kDeltaUsedToBuildTable); 83 84 SkASSERT(mask->fFormat == SkMask::k3D_Format); 85 86 int specular = light.fSpecular; 87 int ambient = light.fAmbient; 88 SkFixed lx = SkScalarToFixed(light.fDirection[0]); 89 SkFixed ly = SkScalarToFixed(light.fDirection[1]); 90 SkFixed lz = SkScalarToFixed(light.fDirection[2]); 91 SkFixed lz_dot_nz = lz * kDelta; 92 int lz_dot8 = lz >> 8; 93 94 size_t planeSize = mask->computeImageSize(); 95 uint8_t* alpha = mask->fImage; 96 uint8_t* multiply = (uint8_t*)alpha + planeSize; 97 uint8_t* additive = multiply + planeSize; 98 99 int rowBytes = mask->fRowBytes; 100 int maxy = mask->fBounds.height() - 1; 101 int maxx = mask->fBounds.width() - 1; 102 103 int prev_row = 0; 104 for (int y = 0; y <= maxy; y++) { 105 int next_row = neq_to_mask(y, maxy) & rowBytes; 106 107 for (int x = 0; x <= maxx; x++) { 108 if (alpha[x]) { 109 int nx = alpha[x + neq_to_one(x, maxx)] - alpha[x - nonzero_to_one(x)]; 110 int ny = alpha[x + next_row] - alpha[x - prev_row]; 111 112 SkFixed numer = lx * nx + ly * ny + lz_dot_nz; 113 int mul = ambient; 114 int add = 0; 115 116 if (numer > 0) { // preflight when numer/denom will be <= 0 117 #if 0 118 int denom = SkSqrt32(nx * nx + ny * ny + kDelta*kDelta); 119 SkFixed dot = numer / denom; 120 dot >>= 8; // now dot is 2^8 instead of 2^16 121 #else 122 // can use full numer, but then we need to call SkFixedMul, since 123 // numer is 24 bits, and our table is 12 bits 124 125 // SkFixed dot = SkFixedMul(numer, gTable[]) >> 8 126 SkFixed dot = (unsigned)(numer >> 4) * gInvSqrtTable[(SkAbs32(nx) >> 1 << 7) | (SkAbs32(ny) >> 1)] >> 20; 127 #endif 128 mul = SkFastMin32(mul + dot, 255); 129 130 // now for the reflection 131 132 // R = 2 (Light * Normal) Normal - Light 133 // hilite = R * Eye(0, 0, 1) 134 135 int hilite = (2 * dot - lz_dot8) * lz_dot8 >> 8; 136 if (hilite > 0) { 137 // pin hilite to 255, since our fast math is also a little sloppy 138 hilite = SkClampMax(hilite, 255); 139 140 // specular is 4.4 141 // would really like to compute the fractional part of this 142 // and then possibly cache a 256 table for a given specular 143 // value in the light, and just pass that in to this function. 144 add = hilite; 145 for (int i = specular >> 4; i > 0; --i) { 146 add = div255(add * hilite); 147 } 148 } 149 } 150 multiply[x] = SkToU8(mul); 151 additive[x] = SkToU8(add); 152 153 // multiply[x] = 0xFF; 154 // additive[x] = 0; 155 // ((uint8_t*)alpha)[x] = alpha[x] * multiply[x] >> 8; 156 } 157 } 158 alpha += rowBytes; 159 multiply += rowBytes; 160 additive += rowBytes; 161 prev_row = rowBytes; 162 } 163 } 164
