Add settings for BPTC compression

BPTCEncoder/include/BPTCCompressor.h

@@ -82,6 +82,67 @@
 #include <iosfwd>
 
 namespace BPTCC {
+  // The various available block modes that a BPTC compressor can choose from.
+  // The enum is specialized to be power-of-two values so that an EBlockMode
+  // variable can be used as a bit mask.
+  enum EBlockMode {
+    eBlockMode_Zero = 0,
+    eBlockMode_One = 1,
+    eBlockMode_Two = 2,
+    eBlockMode_Three = 4,
+    eBlockMode_Four = 8,
+    eBlockMode_Five = 16,
+    eBlockMode_Six = 32,
+    eBlockMode_Seven = 64
+  };
+
+  // A shape selection can influence the results of the compressor by choosing
+  // different modes to compress or not compress. The shape index is a value
+  // between zero and sixty-four that corresponds to one of the available
+  // partitioning schemes defined by the BPTC format.
+  struct ShapeSelection {
+    // This is the shape index to use when evaluating two-partition shapes.
+    uint32 m_TwoShapeIndex;
+
+    // This is the shape index to use when evaluating three-partition shapes.
+    uint32 m_ThreeShapeIndex;
+
+    // This is the additional mask to prevent modes once shape selection
+    // is done. This value is &-ed with m_BlockModes from CompressionSettings
+    // to determine what the final considered blocks are.
+    EBlockMode m_AdditionalModes;
+  };
+
+  // A shape selection function is one that selects a BPTC shape from a given
+  // block position and pixel array.
+  typedef ShapeSelection
+    (*ShapeSelectionFn)(uint32 x, uint32 y, uint32 pixels[16]);
+
+  // Compression parameters used to control the BPTC compressor. Each of the
+  // values has a default, so this is not strictly required to perform
+  // compression, but some aspects of the compressor can be user-defined or
+  // overridden.
+  struct CompressionSettings {
+    // The shape selection function to use during compression. The default (when
+    // this variable is set to NULL) is to use the diagonal of the axis-aligned
+    // bounding box of every partition to estimate the error using that
+    // partition would accrue. The shape with the least error is then chosen.
+    // This procedure is done for both two and three partition shapes, and then
+    // every block mode is still available.
+    ShapeSelectionFn m_ShapeSelectionFn;
+
+    // The block modes that the compressor will consider during compression.
+    // This variable is a bit mask of EBlockMode values and by default contains
+    // every mode. This setting can be used to further restrict the search space
+    // and increase compression times.
+    EBlockMode m_BlockModes;
+
+    CompressionSettings()
+    : m_ShapeSelectionFn(NULL)
+    , m_BlockModes(static_cast<EBlockMode>((1 << 7) - 1))
+    { }
+  };
+
   // This is the error metric that is applied to our error measurement algorithm
   // in order to bias calculation towards results that are more in-line with
   // how the Human Visual System works. Uniform error means that each color
@@ -114,13 +175,15 @@ namespace BPTCC {
 
   // Compress the image given as RGBA data to BPTC format. Width and Height are
   // the dimensions of the image in pixels.
-  void Compress(const FasTC::CompressionJob &);
+  void Compress(const FasTC::CompressionJob &,
+                CompressionSettings settings = CompressionSettings());
 
   // Perform a compression while recording all of the choices the compressor
   // made into a list of statistics. We can use this to see whether or not
   // certain heuristics are working, such as whether or not certain modes are
   // being chosen more often than others, etc.
-  void CompressWithStats(const FasTC::CompressionJob &, std::ostream *logStream);
+  void CompressWithStats(const FasTC::CompressionJob &, std::ostream *logStream,
+                         CompressionSettings settings = CompressionSettings());
 
 #ifdef HAS_SSE_41
   // Compress the image given as RGBA data to BPTC format using an algorithm
@@ -146,8 +209,7 @@ namespace BPTCC {
                              std::ostream *logStream);
 #endif
 
-  // Decompress the image given as BPTC data to R8G8B8A8 format. Width and Height
+  // Decompress the image given as BPTC data to R8G8B8A8 format.
-  // are the dimensions of the image in pixels.
   void Decompress(const FasTC::DecompressionJob &);
 }  // namespace BPTCC
 

BPTCEncoder/src/Compressor.cpp

@@ -1553,9 +1553,13 @@ std::ostream &operator<<(const BlockLogger &bl, const T &v) {
 }
 
 // Function prototypes
-static void CompressBC7Block(const uint32 *block, uint8 *outBuf);
 static void CompressBC7Block(
-  const uint32 *block, uint8 *outBuf, const BlockLogger &logStream
+  const uint32 block[16], uint8 *outBuf,
+  const CompressionSettings = CompressionSettings()
+);
+static void CompressBC7Block(
+  const uint32 block[16], uint8 *outBuf, const BlockLogger &logStream,
+  const CompressionSettings = CompressionSettings()
 );
 
 static int gQualityLevel = 50;
@@ -1638,7 +1642,7 @@ void GetBlock(const uint32 x, const uint32 y, const uint32 pixelsWide,
 // the size of the image in pixels. The buffer pointed to by outBuf should be
 // large enough to store the compressed image. This implementation has an 4:1
 // compression ratio.
-void Compress(const FasTC::CompressionJob &cj) {
+void Compress(const FasTC::CompressionJob &cj, CompressionSettings settings) {
   const uint32 *inPixels = reinterpret_cast<const uint32 *>(cj.InBuf());
   const uint32 kBlockSz = GetBlockSize(FasTC::eCompressionFormat_BPTC);
   uint8 *outBuf = cj.OutBuf() + cj.CoordsToBlockIdx(cj.XStart(), cj.YStart()) * kBlockSz;
@@ -1651,7 +1655,7 @@ void Compress(const FasTC::CompressionJob &cj) {
 
       uint32 block[16];
       GetBlock(i, j, cj.Width(), inPixels, block);
-      CompressBC7Block(block, outBuf);
+      CompressBC7Block(block, outBuf, settings);
 
 #ifndef NDEBUG
       const uint8 *inBlock = reinterpret_cast<const uint8 *>(block);
@@ -1740,7 +1744,8 @@ void CompressAtomic(FasTC::CompressionJobList &cjl) {
 }
 #endif  // HAS_ATOMICS
 
-void CompressWithStats(const FasTC::CompressionJob &cj, std::ostream *logStream) {
+  void CompressWithStats(const FasTC::CompressionJob &cj, std::ostream *logStream,
+                         CompressionSettings settings) {
   const uint32 *inPixels = reinterpret_cast<const uint32 *>(cj.InBuf());
   const uint32 kBlockSz = GetBlockSize(FasTC::eCompressionFormat_BPTC);
   uint8 *outBuf = cj.OutBuf() + cj.CoordsToBlockIdx(cj.XStart(), cj.YStart()) * kBlockSz;
@@ -1755,9 +1760,9 @@ void CompressWithStats(const FasTC::CompressionJob &cj, std::ostream *logStream)
 
       if(logStream) {
         uint64 blockIdx = cj.CoordsToBlockIdx(i, j);
-        CompressBC7Block(block, outBuf, BlockLogger(blockIdx, *logStream));
+        CompressBC7Block(block, outBuf, BlockLogger(blockIdx, *logStream), settings);
       } else {
-        CompressBC7Block(block, outBuf);
+        CompressBC7Block(block, outBuf, settings);
       }
 
 #ifndef NDEBUG
@@ -1992,7 +1997,8 @@ static double EstimateThreeClusterError(RGBACluster &c) {
   return error;
 }
 
-static void CompressBC7Block(const uint32 *block, uint8 *outBuf) {
+static void CompressBC7Block(const uint32 block[16], uint8 *outBuf,
+                             const CompressionSettings settings) {
   // All a single color?
   if(AllOneColor(block)) {
     BitStream bStrm(outBuf, 128, 0);
@@ -2253,7 +2259,8 @@ static void PrintStat(const BlockLogger &lgr, const char *stat, const T &v) {
 
 // Compress a single block but collect statistics as well...
 static void CompressBC7Block(
-  const uint32 *block, uint8 *outBuf, const BlockLogger &logStream
+  const uint32 block[16], uint8 *outBuf, const BlockLogger &logStream,
+  const CompressionSettings settings
 ) {
 
   class RAIIStatSaver {

Core/src/TexComp.cpp

@@ -76,6 +76,15 @@ static inline T sad(const T &a, const T &b) {
   return (a > b)? a - b : b - a;
 }
 
+static void CompressBPTC(const CompressionJob &cj) {
+  BPTCC::Compress(cj);
+}
+
+static void CompressBPTCWithStats(const CompressionJob &cj,
+                                  std::ostream *strm) {
+  BPTCC::CompressWithStats(cj, strm);
+}
+
 static void CompressPVRTC(const CompressionJob &cj) {
   PVRTCC::Compress(cj);
 }
@@ -109,7 +118,7 @@ static  CompressionFuncWithStats ChooseFuncFromSettingsWithStats(const SCompress
        return BPTCC::CompressNVTTWithStats;
       else
 #endif
-       return BPTCC::CompressWithStats;
+       return CompressBPTCWithStats;
     }
     break;
     
@@ -138,7 +147,7 @@ static CompressionFunc ChooseFuncFromSettings(const SCompressionSettings &s) {
        return BPTCC::CompressNVTT;
       else
 #endif
-       return BPTCC::Compress;
+       return CompressBPTC;
     }
     break;
 
@@ -223,7 +232,7 @@ class AtomicThreadUnit : public TCCallable {
   virtual ~AtomicThreadUnit() { }
   virtual void operator()() {
     m_Barrier->Wait();
-    if(m_CmpFnc == BPTCC::Compress) {
+    if(m_CmpFnc == CompressBPTC) {
       BPTCC::CompressAtomic(m_CompressionJobList);
     }
     else {