Working to make compression handing more robust.

library/PolyVoxCore/include/PolyVoxCore/Compressor.h

@@ -34,7 +34,14 @@ namespace PolyVox
 		Compressor() {};
 		virtual ~Compressor() {};
 
+		// Computes a worst-case scenario for how big the output can be for a given input size. If
+		// necessary you can use this as a destination buffer size, though it may be somewhat wasteful.
+		virtual uint32_t getMaxCompressedSize(uint32_t uUncompressedInputSize) = 0;
+
+		// Compresses the data.
 		virtual uint32_t compress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength) = 0;
+
+		// Decompresses the data.
 		virtual uint32_t decompress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength) = 0;
 	};
 }

library/PolyVoxCore/include/PolyVoxCore/Impl/Block.inl

@@ -150,19 +150,52 @@ namespace PolyVox
 		if(m_bIsUncompressedDataModified)
 		{
 			void* pSrcData = reinterpret_cast<void*>(m_tUncompressedData);
-			void* pDstData = reinterpret_cast<void*>( new uint8_t[1000000] );
 			uint32_t uSrcLength = m_uSideLength * m_uSideLength * m_uSideLength * sizeof(VoxelType);
+
+			void* pDstData = 0;
+			uint32_t uCompressedLength = 0;
+
+			try
+			{
+				uint8_t buffer[1000000];
+
+				pDstData = reinterpret_cast<void*>( buffer );				
 				uint32_t uDstLength = 1000000;
 
-			//MinizCompressor compressor;
-			//RLECompressor<VoxelType, uint16_t> compressor;
-			uint32_t uCompressedLength = pCompressor->compress(pSrcData, uSrcLength, pDstData, uDstLength);
+				uCompressedLength = pCompressor->compress(pSrcData, uSrcLength, pDstData, uDstLength);
+			}
+			catch(std::exception& e)
+			{
+				// It is possible for the compression to fail. A common cause for this would be if the destination
+				// buffer is not big enough. So now we try again using a buffer that is definitely big enough.
+				uint32_t uMaxCompressedSize = pCompressor->getMaxCompressedSize(uSrcLength);
+				uint8_t* buffer = new uint8_t[ uMaxCompressedSize ];
 
+				pDstData = reinterpret_cast<void*>( buffer );				
+				uint32_t uDstLength = uMaxCompressedSize;
+
+				try
+				{		
+					uCompressedLength = pCompressor->compress(pSrcData, uSrcLength, pDstData, uDstLength);
+				}
+				catch(std::exception& e)
+				{
+					// At this point it didn't work even with a bigger buffer.
+					// Not much more we can do so just rethrow the exception.
+					delete buffer;
+					POLYVOX_THROW(std::runtime_error, "Failed to compress block data");
+				}
+
+				delete buffer;
+			}
+
+			// Delete the old compressed data and assign a new one
+			delete m_pCompressedData;
 			m_pCompressedData = reinterpret_cast<void*>( new uint8_t[uCompressedLength] );
+
+			//Copy the data across
 			memcpy(m_pCompressedData, pDstData, uCompressedLength);
 			m_uCompressedDataLength = uCompressedLength;
-
-			delete pDstData;
 		}
 
 		//Flag the uncompressed data as no longer being used.

library/PolyVoxCore/include/PolyVoxCore/LargeVolume.inl

@@ -619,7 +619,9 @@ namespace PolyVox
 			// create the new block
 			LoadedBlock newBlock(m_uBlockSideLength);
 
-			//Blocks start out compressed - should we change this?
+			// Blocks start out compressed - should we change this?
+			// Or maybe we should just 'seed' them with compressed data,
+			// rather than creating an empty block and then compressing?
 			newBlock.block.compress(m_pCompressor);
 
 			itBlock = m_pBlocks.insert(std::make_pair(v3dBlockPos, newBlock)).first;

library/PolyVoxCore/include/PolyVoxCore/MinizCompressor.h

@@ -11,6 +11,7 @@ namespace PolyVox
 		MinizCompressor();
 		~MinizCompressor();
 
+		uint32_t getMaxCompressedSize(uint32_t uUncompressedInputSize);
 		uint32_t compress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength);
 		uint32_t decompress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength);
 	};

library/PolyVoxCore/include/PolyVoxCore/RLECompressor.h

@@ -17,6 +17,7 @@ namespace PolyVox
 		RLECompressor();
 		~RLECompressor();
 
+		uint32_t getMaxCompressedSize(uint32_t uUncompressedInputSize);
 		uint32_t compress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength);
 		uint32_t decompress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength);
 	};

library/PolyVoxCore/include/PolyVoxCore/RLECompressor.inl

@@ -14,6 +14,13 @@ namespace PolyVox
 	{
 	}
 
+	template<typename ValueType, typename LengthType>
+	uint32_t RLECompressor<ValueType, LengthType>::getMaxCompressedSize(uint32_t uUncompressedInputSize)
+	{
+		// In the worst case we will have a seperate Run (of length one) for each element of the input data.
+		return uUncompressedInputSize * sizeof(Run);
+	}
+
 	template<typename ValueType, typename LengthType>
 	uint32_t RLECompressor<ValueType, LengthType>::compress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength)
 	{

library/polyvoxcore/source/MinizCompressor.cpp

@@ -29,6 +29,11 @@ namespace PolyVox
 	{
 	}
 
+	uint32_t MinizCompressor::getMaxCompressedSize(uint32_t uUncompressedInputSize)
+	{
+		return static_cast<uint32_t>(mz_compressBound(static_cast<mz_ulong>(uUncompressedInputSize)));
+	}
+
 	uint32_t MinizCompressor::compress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength)
 	{
 		mz_ulong ulDstLength = uDstLength;