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
nonzero_to_one(int x)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
neq_to_one(int x,int max)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
neq_to_mask(int x,int max)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
div255(unsigned x)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
SkEmbossMask_BuildTable()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
Emboss(SkMask * mask,const SkEmbossMaskFilter::Light & light)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