Updated ib-compress.

3rdparty/ib-compress/indexbuffercompression.cpp

@@ -525,8 +525,8 @@ void CompressTriangleCodes1( const Ty* triangles,
 				break;
 			}
 
-			default: // IB_EDGE_NEW, IB_EDGE_CACHED, IB_EDGE_0_NEW, IB_EDGE_1_NEW
-				break;
+            default: // IB_EDGE_NEW, IB_EDGE_CACHED, IB_EDGE_0_NEW, IB_EDGE_1_NEW
+                break;
 			}
 
 			// populate the edge fifo with the 3 most recent edges
@@ -747,6 +747,25 @@ void CompressIndiceCodes1( const Ty* triangles,
 	}
 }
 
+// Detects if there are any degenerate triangles in a set of triangles, where there is 1 or more duplicate vertices.
+template <typename Ty>
+bool ContainsDegenerates( const Ty* triangles, uint32_t triangleCount )
+{
+    const Ty* triangleEnd = triangles + ( triangleCount * 3 );
+    bool      result      = false;
+
+    for ( const Ty* triangle = triangles; triangle < triangleEnd; triangle += 3 )
+    {
+        if ( triangle[ 0 ] == triangle[ 1 ] || triangle[ 0 ] == triangle[ 2 ] || triangle[ 1 ] == triangle[ 2 ] )
+        {
+            result = true;
+            break;
+        }
+    }
+
+    return result;
+}
+
 template <typename Ty>
 void CompressIndexBuffer( const Ty* triangles,
 						  uint32_t triangleCount,
@@ -755,19 +774,34 @@ void CompressIndexBuffer( const Ty* triangles,
 						  IndexBufferCompressionFormat format,
 						  WriteBitstream& output )
 {
-	output.WriteVInt( format );
-
 	switch ( format )
 	{
 	case IBCF_PER_INDICE_1:
 
+        output.WriteVInt( IBCF_PER_INDICE_1 );
 		CompressIndiceCodes1<Ty>( triangles, triangleCount, vertexRemap, vertexCount, output );
 		break;
 
 	case IBCF_PER_TRIANGLE_1:
 
+        output.WriteVInt( IBCF_PER_TRIANGLE_1 );
 		CompressTriangleCodes1<Ty>( triangles, triangleCount, vertexRemap, vertexCount, output );
 		break;
+
+    case ICBF_AUTO:
+
+        if ( ContainsDegenerates( triangles, triangleCount ) )
+        {
+            output.WriteVInt( IBCF_PER_INDICE_1 );
+            CompressIndiceCodes1<Ty>( triangles, triangleCount, vertexRemap, vertexCount, output );
+        }
+        else
+        {
+            output.WriteVInt( IBCF_PER_TRIANGLE_1 );
+            CompressTriangleCodes1<Ty>( triangles, triangleCount, vertexRemap, vertexCount, output );
+        }
+
+        break;
 	}
 }
 

3rdparty/ib-compress/indexbuffercompression.h

@@ -38,8 +38,11 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 // Parameters: 
 //     [in]  triangles      - A typical triangle list index buffer (3 indices to vertices per triangle). 16 bit indices.
 //     [in]  triangle count - The number of triangles to process.
-//     [out] vertexRemap    - This will be populated with re-mappings that map old vertices to new vertices,
-//                            where indexing with the old vertex index will get you the new one. 
+//     [out] vertexRemap    - This will be populated with re-mappings that map old vertices to new vertex locations (a new ordering),
+//                            where indexing with the old vertex index will get you the new one. Vertices that are unused will 
+//                            be mapped to 0xFFFFFFFF.
+//                            You should re-order the vertices and removed unused ones based on the vertex remap, instead of storing
+//                            the remap. 
 //                            It should be allocated as a with at least vertexCount entries.
 //     [in] vertexCount     - The number of vertices in the mesh. This should be less than 0xFFFFFFFF/2^32 - 1.
 //     [in] format          - The compression format to use for encoding - note the format will be encoded with the compressed data so the decompressor can select the correct algorithm.            

3rdparty/ib-compress/indexbuffercompressionformat.h

@@ -8,7 +8,11 @@ enum IndexBufferCompressionFormat
 	IBCF_PER_INDICE_1 = 0,
 
 	// Per triangle encoding - better compression/speed, does not handle degenerates.
-	IBCF_PER_TRIANGLE_1 = 1
+	IBCF_PER_TRIANGLE_1 = 1,
+
+    // Automatically pick the best encoding dependent on whether degenerate triangles are detected in the mesh.
+    // Will take longer to compress (due to the degenerate triangle check).
+    ICBF_AUTO = 2
 };
 
 #endif // -- INDEX_BUFFER_COMPRESSION_FORMAT_H__

3rdparty/ib-compress/indexbufferdecompression.cpp

@@ -465,6 +465,8 @@ void DecompressIndexBuffer( Ty* triangles, uint32_t triangleCount, ReadBitstream
 		DecompressTriangleCodes1<Ty>( triangles, triangleCount, input );
 		break;
 
+	default: // ICBF_AUTO:
+		break;
 	}
 }
 

README.md

@@ -649,6 +649,10 @@ https://github.com/memononen/SDF
 
 http://nothings.org
 
+### Vertex Cache Optimised Index Buffer Compression
+
+https://github.com/ConorStokes/IndexBufferCompression
+
 Assets
 ------
 

tools/geometryc/geometryc.cpp

@@ -115,7 +115,6 @@ typedef std::vector<Primitive> PrimitiveArray;
 
 static uint32_t s_obbSteps = 17;
 
-#define BGFX_CHUNK_MAGIC_GEO BX_MAKEFOURCC('G', 'E', 'O', 0x0)
 #define BGFX_CHUNK_MAGIC_VB  BX_MAKEFOURCC('V', 'B', ' ', 0x1)
 #define BGFX_CHUNK_MAGIC_IB  BX_MAKEFOURCC('I', 'B', ' ', 0x0)
 #define BGFX_CHUNK_MAGIC_IBC BX_MAKEFOURCC('I', 'B', 'C', 0x0)
@@ -143,7 +142,7 @@ void triangleCompress(bx::WriterI* _writer, uint16_t* _indices, uint32_t _numInd
 	uint32_t* vertexRemap = (uint32_t*)malloc(_numVertices*sizeof(uint32_t) );
 
 	WriteBitstream writer;
-	CompressIndexBuffer(_indices, _numIndices/3, vertexRemap, _numVertices, IBCF_PER_TRIANGLE_1, writer);
+	CompressIndexBuffer(_indices, _numIndices/3, vertexRemap, _numVertices, ICBF_AUTO, writer);
 	writer.Finish();
 	printf( "uncompressed: %10d, compressed: %10d, ratio: %0.2f%%\n"
 		, _numIndices * 2
@@ -155,10 +154,9 @@ void triangleCompress(bx::WriterI* _writer, uint16_t* _indices, uint32_t _numInd
 	uint8_t* outVertexData = (uint8_t*)malloc(_numVertices*_stride);
 	for (uint32_t ii = 0; ii < _numVertices; ++ii)
 	{
-		if (UINT32_MAX != vertexRemap[ii])
-		{
-			memcpy(&outVertexData[vertexRemap[ii]*_stride], &_vertexData[ii*_stride], _stride);
-		}
+		uint32_t remap = vertexRemap[ii];
+		remap = UINT32_MAX == remap ? ii : remap;
+		memcpy(&outVertexData[remap*_stride], &_vertexData[ii*_stride], _stride);
 	}
 	memcpy(_vertexData, outVertexData, _numVertices*_stride);
 	free(outVertexData);