// using EtcPack to decode ETC1
void CodecETC1_Decode(TexDecodeTask *task)
{
byte *data, *stream;
int x, y, w, h;
size_t size;
w = task->image->width;
h = task->image->height;
size = w * h * task->image->bpp;
data = (byte *)mem_alloc(size);
stream = task->pixeldata;
for (y = 0; y < h / 4; y++)
{
for (x = 0; x < w / 4; x++)
{
// etcpack path
unsigned int block1, block2;
block1 = 0; block1 |= stream[0];
block1 = block1 << 8; block1 |= stream[1];
block1 = block1 << 8; block1 |= stream[2];
block1 = block1 << 8; block1 |= stream[3];
block2 = 0; block2 |= stream[4];
block2 = block2 << 8; block2 |= stream[5];
block2 = block2 << 8; block2 |= stream[6];
block2 = block2 << 8; block2 |= stream[7];
stream += 8;
// ETC2 is backwards compatible, which means that an ETC2-capable decompressor
// can also handle old ETC1 textures without any problems.
etcpack_decompressBlockETC2c(block1, block2, data, w, h, x*4, y*4, task->image->bpp);
}
}
Image_StoreUnalignedData(task->image, data, size);
free(data);
task->image->colorSwap = false;
}
// using EtcPack to decode ETC2
void CodecETC2_Decode(TexDecodeTask *task)
{
byte *data, *stream, rgba[4*4*4], *lb;
unsigned int block1, block2;
int x, y, w, h, bpp;
int lx, ly, lw, lh;
// init
w = task->image->width;
h = task->image->height;
bpp = task->image->bpp;
data = (byte *)mem_alloc(w * h * bpp);
stream = task->pixeldata;
// decode
if (task->format->block == &B_ETC2)
{
for (y = 0; y < h; y+=4)
{
for (x = 0; x < w; x+=4)
{
readColorBlockETC(&stream, block1, block2);
etcpack_decompressBlockETC2c(block1, block2, rgba, 4, 4, 0, 0, 4);
lb = rgba;
lh = min(y + 4, h) - y;
lw = min(x + 4, w) - x;
for (ly = 0; ly < lh; ly++,lb+=4*4)
for(lx = 0; lx < lw; lx++)
memcpy(data + (w*(y + ly) + x + lx)*bpp, lb + lx*4, 3);
}
}
}
else if (task->format->block == &B_ETC2A)
{
for (y = 0; y < h; y+=4)
{
for (x = 0; x < w; x+=4)
{
// EAC block + ETC2 RGB block
etcpack_decompressBlockAlphaC(stream, rgba+3, 4, 4, 0, 0, 4);
stream += 8;
readColorBlockETC(&stream, block1, block2);
etcpack_decompressBlockETC2c(block1, block2, rgba, 4, 4, 0, 0, 4);
lb = rgba;
lh = min(y + 4, h) - y;
lw = min(x + 4, w) - x;
for (ly = 0; ly < lh; ly++,lb+=4*4)
for(lx = 0; lx < lw; lx++)
memcpy(data + (w*(y + ly) + x + lx)*bpp, lb + lx*4, 4);
}
}
}
else if (task->format->block == &B_ETC2A1)
{
for (y = 0; y < h; y+=4)
{
for (x = 0; x < w; x+=4)
{
// ETC2 RGB/punchthrough alpha block
readColorBlockETC(&stream, block1, block2);
etcpack_decompressBlockETC21BitAlphaC(block1, block2, rgba, NULL, 4, 4, 0, 0, 4);
lb = rgba;
lh = min(y + 4, h) - y;
lw = min(x + 4, w) - x;
for (ly = 0; ly < lh; ly++,lb+=4*4)
for(lx = 0; lx < lw; lx++)
memcpy(data + (w*(y + ly) + x + lx)*bpp, lb + lx*4, 4);
}
}
}
else
Error("CodecETC2_Decode: block %s not supported\n", task->format->block->name);
// store decoded image
Image_StoreUnalignedData(task->image, data, w*h*bpp);
free(data);
task->image->colorSwap = false;
}