Add some better comments

BPTCEncoder/include/FasTC/BPTCCompressor.h

@@ -127,11 +127,11 @@ namespace BPTCC {
   // between zero and sixty-four that corresponds to one of the available
   // partitioning schemes defined by the BPTC format.
   struct ShapeSelection {
-    // This is the number of indices from which to select the appropriate
+    // This is the number of valid shapes in m_Shapes
-    // shapes. I.e. the compressor will try the first m_NumIndices shapes
+    uint32 m_NumShapesToSearch;
-    uint32 m_NumIndices;
 
-    // These are the shape indices to use when evaluating two-partition shapes.
+    // These are the shape indices to use when evaluating shapes. 
+    // I.e. the shapes that the compressor will try to optimize.
     Shape m_Shapes[10];
 
     // This is the additional mask to prevent modes once shape selection
@@ -141,7 +141,7 @@ namespace BPTCC {
 
     // Defaults
     ShapeSelection()
-    : m_NumIndices(0)
+    : m_NumShapesToSearch(0)
     , m_SelectedModes(static_cast<EBlockMode>(0xFF))
     { }
   };

BPTCEncoder/src/Compressor.cpp

@@ -1722,7 +1722,7 @@ static ShapeSelection BoxSelection(
 
   RGBACluster cluster(pixels);
 
-  result.m_NumIndices = 1;
+  result.m_NumShapesToSearch = 1;
   for(unsigned int i = 0; i < kNumShapes2; i++) {
     cluster.SetShapeIndex(i, 2);
 
@@ -1758,7 +1758,7 @@ static ShapeSelection BoxSelection(
     ~(static_cast<uint32>(eBlockMode_Four) |
       static_cast<uint32>(eBlockMode_Five));
 
-  result.m_NumIndices++;
+  result.m_NumShapesToSearch++;
   for(unsigned int i = 0; i < kNumShapes3; i++) {
     cluster.SetShapeIndex(i, 3);
 
@@ -1794,7 +1794,7 @@ static void CompressClusters(const ShapeSelection &selection, const uint32 pixel
   CompressionMode::Params bestParams;
 
   uint32 selectedModes = selection.m_SelectedModes;
-  uint32 numShapeIndices = std::min<uint32>(5, selection.m_NumIndices);
+  uint32 numShapeIndices = std::min<uint32>(5, selection.m_NumShapesToSearch);
 
   // If we don't have any indices, turn off two and three partition modes,
   // since the compressor will simply ignore the shapeIndex variable afterwards...
@@ -2102,7 +2102,7 @@ static void CompressBC7Block(
   ShapeSelection selection;
   uint32 path = 0;
 
-  selection.m_NumIndices = 1;
+  selection.m_NumShapesToSearch = 1;
   for(unsigned int i = 0; i < kNumShapes2; i++) {
     blockCluster.SetShapeIndex(i, 2);
 
@@ -2156,7 +2156,7 @@ static void CompressBC7Block(
   // There are not 3 subset blocks that support alpha, so only check these
   // if the entire block is opaque.
   if(opaque) {
-    selection.m_NumIndices++;
+    selection.m_NumShapesToSearch++;
     for(unsigned int i = 0; i < kNumShapes3; i++) {
       blockCluster.SetShapeIndex(i, 3);
 

DXTEncoder/src/Decompressor.cpp

@@ -61,6 +61,10 @@
 namespace DXTC
 {
   void DecompressDXT1Block(const uint8 *block, uint32 *outBuf) {
+    // When we call FasTC::Pixel::FromBits, we expect the bits
+    // to be read out of memory in LSB (byte) order first. Hence,
+    // we can't read the blocks directly as uint16 values out of
+    // the DXT buffer and we have to swap the bytes before hand.
     uint16 colorA = block[0];
     colorA <<= 8;
     colorA |= block[1];