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Remove alpha channel for DXT1 textures

pull/1087/head
Levin Li 2021-06-13 23:46:55 +08:00
parent 5d1bcc2256
commit c7018259a6
1 changed files with 16 additions and 3 deletions
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19
src/celimage/dds.cpp
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@ -239,7 +239,7 @@ Image* LoadDDSImage(const fs::path& filename)
{
if (!gl::EXT_texture_compression_s3tc)
{
// DXTc texture not supported, decompress DXTc to RGBA
// DXTc texture not supported, decompress DXTc to RGB/RGBA
uint32_t *pixels = nullptr;
bool transparent0 = format == GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
if ((ddsd.width & 3) != 0 || (ddsd.height & 3) != 0)
@ -267,8 +267,21 @@ Image* LoadDDSImage(const fs::path& filename)
return nullptr;
}
Image *img = new Image(GL_RGBA, ddsd.width, ddsd.height);
memcpy(img->getPixels(), pixels, 4 * ddsd.width * ddsd.height);
if (transparent0)
{
// Remove the alpha channel for DXT1 since DXT1 textures
// are deemed not to contain alpha values in Celestia
// https://github.com/CelestiaProject/Celestia/pull/1086
char *ptr = reinterpret_cast<char*>(pixels);
uint32_t numberOfPixels = ddsd.width * ddsd.height;
for (uint32_t index = 0; index < numberOfPixels; ++index)
{
memcpy(&ptr[3 * index], &ptr[4 * index], sizeof(char) * 3);
}
}
Image *img = new Image(transparent0 ? GL_RGB : GL_RGBA, ddsd.width, ddsd.height);
memcpy(img->getPixels(), pixels, (transparent0 ? 3 : 4) * ddsd.width * ddsd.height);
delete[] pixels;
return img;
}