Remove premultiplied alpha

This commit is contained in:
Magnus Norddahl 2016-08-14 05:10:34 +02:00
parent abef073ea4
commit f56250b910
2 changed files with 17 additions and 18 deletions

View file

@ -473,9 +473,9 @@ public:
{
uint32_t alpha = APART(fg) + (APART(fg) >> 7); // 255 -> 256
uint32_t inv_alpha = 256 - alpha;
uint32_t red = MIN<uint32_t>(RPART(fg) + (RPART(bg) * inv_alpha) / 256, 255);
uint32_t green = MIN<uint32_t>(GPART(fg) + (GPART(bg) * inv_alpha) / 256, 255);
uint32_t blue = MIN<uint32_t>(BPART(fg) + (BPART(bg) * inv_alpha) / 256, 255);
uint32_t red = MIN<uint32_t>(RPART(fg) * alpha + (RPART(bg) * inv_alpha) / 256, 255);
uint32_t green = MIN<uint32_t>(GPART(fg) * alpha + (GPART(bg) * inv_alpha) / 256, 255);
uint32_t blue = MIN<uint32_t>(BPART(fg) * alpha + (BPART(bg) * inv_alpha) / 256, 255);
return 0xff000000 | (red << 16) | (green << 8) | blue;
}
};
@ -861,11 +861,18 @@ public:
__m128i fg_lo = _mm_unpacklo_epi8(fg, _mm_setzero_si128()); \
__m128i bg_hi = _mm_unpackhi_epi8(bg, _mm_setzero_si128()); \
__m128i bg_lo = _mm_unpacklo_epi8(bg, _mm_setzero_si128()); \
__m128i m255 = _mm_set1_epi16(255); \
__m128i inv_alpha_hi = _mm_sub_epi16(m255, _mm_shufflehi_epi16(_mm_shufflelo_epi16(fg_hi, _MM_SHUFFLE(3,3,3,3)), _MM_SHUFFLE(3,3,3,3))); \
__m128i inv_alpha_lo = _mm_sub_epi16(m255, _mm_shufflehi_epi16(_mm_shufflelo_epi16(fg_lo, _MM_SHUFFLE(3,3,3,3)), _MM_SHUFFLE(3,3,3,3))); \
inv_alpha_hi = _mm_add_epi16(inv_alpha_hi, _mm_srli_epi16(inv_alpha_hi, 7)); \
inv_alpha_lo = _mm_add_epi16(inv_alpha_lo, _mm_srli_epi16(inv_alpha_lo, 7)); \
__m128i m256 = _mm_set1_epi16(256); \
__m128i alpha_hi = _mm_shufflehi_epi16(_mm_shufflelo_epi16(fg_hi, _MM_SHUFFLE(3,3,3,3)), _MM_SHUFFLE(3,3,3,3)); \
__m128i alpha_lo = _mm_shufflehi_epi16(_mm_shufflelo_epi16(fg_lo, _MM_SHUFFLE(3,3,3,3)), _MM_SHUFFLE(3,3,3,3)); \
alpha_hi = _mm_add_epi16(alpha_hi, _mm_srli_epi16(alpha_hi, 7)); \
alpha_lo = _mm_add_epi16(alpha_lo, _mm_srli_epi16(alpha_lo, 7)); \
__m128i inv_alpha_hi = _mm_sub_epi16(m256, alpha_hi); \
__m128i inv_alpha_lo = _mm_sub_epi16(m256, alpha_lo); \
fg_hi = _mm_mullo_epi16(fg_hi, alpha_hi); \
fg_hi = _mm_srli_epi16(fg_hi, 8); \
fg_lo = _mm_mullo_epi16(fg_lo, alpha_lo); \
fg_lo = _mm_srli_epi16(fg_lo, 8); \
fg = _mm_packus_epi16(fg_lo, fg_hi); \
bg_hi = _mm_mullo_epi16(bg_hi, inv_alpha_hi); \
bg_hi = _mm_srli_epi16(bg_hi, 8); \
bg_lo = _mm_mullo_epi16(bg_lo, inv_alpha_lo); \

View file

@ -354,22 +354,14 @@ void FTexture::GenerateBgraFromBitmap(const FBitmap &bitmap)
{
CreatePixelsBgraWithMipmaps();
// Transpose and premultiply alpha
// Transpose
const uint32_t *src = (const uint32_t *)bitmap.GetPixels();
uint32_t *dest = PixelsBgra.data();
for (int x = 0; x < Width; x++)
{
for (int y = 0; y < Height; y++)
{
uint32_t p = src[x + y * Width];
uint32_t red = RPART(p);
uint32_t green = GPART(p);
uint32_t blue = BPART(p);
uint32_t alpha = APART(p);
red = (red * alpha + 127) / 255;
green = (green * alpha + 127) / 255;
blue = (blue * alpha + 127) / 255;
dest[y + x * Height] = (alpha << 24) | (red << 16) | (green << 8) | blue;
dest[y + x * Height] = src[x + y * Width];
}
}