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Convert to premultiplied alpha

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This commit is contained in:
mkwong98 2019-08-30 13:51:21 +08:00
parent 373c489b01
commit 8b42a55b19
2 changed files with 24 additions and 5 deletions
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7
Core/HdNesPack.cpp
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@ -21,11 +21,10 @@ HdNesPack::~HdNesPack()
void HdNesPack::BlendColors(uint8_t output[4], uint8_t input[4])
{
uint8_t alpha = input[3] + 1;
uint8_t invertedAlpha = 256 - input[3];
output[0] = (uint8_t)((alpha * input[0] + invertedAlpha * output[0]) >> 8);
output[1] = (uint8_t)((alpha * input[1] + invertedAlpha * output[1]) >> 8);
output[2] = (uint8_t)((alpha * input[2] + invertedAlpha * output[2]) >> 8);
output[0] = (uint8_t)((input[0] + invertedAlpha * output[0]) >> 8);
output[1] = (uint8_t)((input[1] + invertedAlpha * output[1]) >> 8);
output[2] = (uint8_t)((input[2] + invertedAlpha * output[2]) >> 8);
output[3] = 0xFF;
}

20
Core/HdPackLoader.cpp
View file

@ -213,6 +213,16 @@ bool HdPackLoader::ProcessImgTag(string src)
bitmapInfo.PixelData.resize(pixelData.size() / 4);
memcpy(bitmapInfo.PixelData.data(), pixelData.data(), bitmapInfo.PixelData.size() * sizeof(bitmapInfo.PixelData[0]));
//premultiply alpha
for (int i = 0; i < bitmapInfo.PixelData.size(); ++i) {
if (bitmapInfo.PixelData[i] < 0xFF000000) {
uint8_t output[4] = (uint8_t*)&(bitmapInfo.PixelData[i]);
uint8_t alpha = output[3] + 1;
output[0] = (uint8_t)((alpha * output[0]) >> 8);
output[1] = (uint8_t)((alpha * output[1]) >> 8);
output[2] = (uint8_t)((alpha * output[2]) >> 8);
}
}
_hdNesBitmaps.push_back(bitmapInfo);
return true;
} else {
@ -541,6 +551,16 @@ void HdPackLoader::ProcessBackgroundTag(vector<string> &tokens, vector<HdPackCon
bgFileData = _data->BackgroundFileData.back().get();
bgFileData->PixelData.resize(pixelData.size() / 4);
memcpy(bgFileData->PixelData.data(), pixelData.data(), bgFileData->PixelData.size() * sizeof(bgFileData->PixelData[0]));
//premultiply alpha
for (int i = 0; i < bgFileData->PixelData.size(); ++i) {
if (bgFileData->PixelData[i] < 0xFF000000) {
uint8_t output[4] = (uint8_t*)&(bgFileData->PixelData[i]);
uint8_t alpha = output[3] + 1;
output[0] = (uint8_t)((alpha * output[0]) >> 8);
output[1] = (uint8_t)((alpha * output[1]) >> 8);
output[2] = (uint8_t)((alpha * output[2]) >> 8);
}
}
bgFileData->Width = width;
bgFileData->Height = height;
bgFileData->PngName = tokens[0];