public static Bc7Block EncodeBlock(RawBlock4X4Rgba32 block, int startingVariation, int bestPartition)
{
Bc7Block output = new Bc7Block();
const Bc7BlockType type = Bc7BlockType.Type2;
ColorRgba32[] endpoints = new ColorRgba32[6];
ReadOnlySpan <int> partitionTable = Bc7Block.Subsets3PartitionTable[bestPartition];
byte[] indices = new byte[16];
int[] anchorIndices = new int[] {
0,
Bc7Block.Subsets3AnchorIndices2[bestPartition],
Bc7Block.Subsets3AnchorIndices3[bestPartition]
};
for (int subset = 0; subset < 3; subset++)
{
Bc7EncodingHelpers.GetInitialUnscaledEndpointsForSubset(block, out var ep0, out var ep1,
partitionTable, subset);
ColorRgba32 scaledEp0 =
Bc7EncodingHelpers.ScaleDownEndpoint(ep0, type, true, out byte _);
ColorRgba32 scaledEp1 =
Bc7EncodingHelpers.ScaleDownEndpoint(ep1, type, true, out byte _);
byte pBit = 0;
Bc7EncodingHelpers.OptimizeSubsetEndpointsWithPBit(type, block, ref scaledEp0,
ref scaledEp1, ref pBit, ref pBit, startingVariation, partitionTable, subset, false, false);
ep0 = Bc7EncodingHelpers.ExpandEndpoint(type, scaledEp0, 0);
ep1 = Bc7EncodingHelpers.ExpandEndpoint(type, scaledEp1, 0);
Bc7EncodingHelpers.FillSubsetIndices(type, block,
ep0,
ep1,
partitionTable, subset, indices);
if ((indices[anchorIndices[subset]] & 0b10) > 0) //If anchor index most significant bit is 1, switch endpoints
{
var c = scaledEp0;
scaledEp0 = scaledEp1;
scaledEp1 = c;
//redo indices
ep0 = Bc7EncodingHelpers.ExpandEndpoint(type, scaledEp0, 0);
ep1 = Bc7EncodingHelpers.ExpandEndpoint(type, scaledEp1, 0);
Bc7EncodingHelpers.FillSubsetIndices(type, block,
ep0,
ep1,
partitionTable, subset, indices);
}
endpoints[subset * 2] = scaledEp0;
endpoints[subset * 2 + 1] = scaledEp1;
}
output.PackType2(bestPartition, new[] {
new byte[] { endpoints[0].r, endpoints[0].g, endpoints[0].b },
new byte[] { endpoints[1].r, endpoints[1].g, endpoints[1].b },
new byte[] { endpoints[2].r, endpoints[2].g, endpoints[2].b },
new byte[] { endpoints[3].r, endpoints[3].g, endpoints[3].b },
new byte[] { endpoints[4].r, endpoints[4].g, endpoints[4].b },
new byte[] { endpoints[5].r, endpoints[5].g, endpoints[5].b }
},
indices);
return(output);
}
public static Bc7Block EncodeBlock(RawBlock4X4Rgba32 block, int startingVariation)
{
bool hasAlpha = block.HasTransparentPixels();
Bc7Block output = new Bc7Block();
Bc7EncodingHelpers.GetInitialUnscaledEndpoints(block, out var ep0, out var ep1);
ColorRgba32 scaledEp0 =
Bc7EncodingHelpers.ScaleDownEndpoint(ep0, Bc7BlockType.Type6, false, out byte pBit0);
ColorRgba32 scaledEp1 =
Bc7EncodingHelpers.ScaleDownEndpoint(ep1, Bc7BlockType.Type6, false, out byte pBit1);
ReadOnlySpan<int> partitionTable = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
const int subset = 0;
//Force 255 alpha if fully opaque
if (!hasAlpha)
{
pBit0 = 1;
pBit1 = 1;
}
Bc7EncodingHelpers.OptimizeSubsetEndpointsWithPBit(Bc7BlockType.Type6, block, ref scaledEp0,
ref scaledEp1, ref pBit0, ref pBit1, startingVariation, partitionTable, subset, hasAlpha, hasAlpha);
ep0 = Bc7EncodingHelpers.ExpandEndpoint(Bc7BlockType.Type6, scaledEp0, pBit0);
ep1 = Bc7EncodingHelpers.ExpandEndpoint(Bc7BlockType.Type6, scaledEp1, pBit1);
byte[] indices = new byte[16];
Bc7EncodingHelpers.FillSubsetIndices(Bc7BlockType.Type6, block,
ep0,
ep1,
partitionTable, subset, indices);
if ((indices[0] & 0b1000) > 0) //If anchor index most significant bit is 1, switch endpoints
{
var c = scaledEp0;
var p = pBit0;
scaledEp0 = scaledEp1;
pBit0 = pBit1;
scaledEp1 = c;
pBit1 = p;
//redo indices
ep0 = Bc7EncodingHelpers.ExpandEndpoint(Bc7BlockType.Type6, scaledEp0, pBit0);
ep1 = Bc7EncodingHelpers.ExpandEndpoint(Bc7BlockType.Type6, scaledEp1, pBit1);
Bc7EncodingHelpers.FillSubsetIndices(Bc7BlockType.Type6, block,
ep0,
ep1,
partitionTable, subset, indices);
}
output.PackType6(new[]{
new byte[]{scaledEp0.r, scaledEp0.g, scaledEp0.b, scaledEp0.a},
new byte[]{scaledEp1.r, scaledEp1.g, scaledEp1.b, scaledEp1.a},
},
new[] { pBit0, pBit1 },
indices);
return output;
}