/* * 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; } }