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- /*
- * 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 "src/effects/SkEmbossMask.h"
- #include "include/core/SkMath.h"
- #include "include/private/SkFixed.h"
- #include "include/private/SkTo.h"
- #include "src/core/SkMathPriv.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
- void SkEmbossMask::Emboss(SkMask* mask, const SkEmbossMaskFilter::Light& light) {
- 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++) {
- 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
- int denom = SkSqrt32(nx * nx + ny * ny + kDelta*kDelta);
- SkFixed dot = numer / denom;
- dot >>= 8; // now dot is 2^8 instead of 2^16
- mul = SkMin32(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);
- }
- alpha += rowBytes;
- multiply += rowBytes;
- additive += rowBytes;
- prev_row = rowBytes;
- }
- }
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