From ae3ac704e401a1516d0597cdc7ff5ffdbd59bc52 Mon Sep 17 00:00:00 2001
From: David Williams <david@david-williams.info>
Date: Sun, 23 Jan 2011 17:41:06 +0000
Subject: [PATCH] Brought back extractSubset from Thermite. Fixed to work with
 PositionMaterial vertices. Also made it a free function.

---
 .../include/AmbientOcclusionCalculator.inl    |  6 +-
 library/PolyVoxCore/include/SurfaceMesh.h     |  3 +
 library/PolyVoxCore/include/SurfaceMesh.inl   | 67 +++++++++++++++++++
 3 files changed, 73 insertions(+), 3 deletions(-)

diff --git a/library/PolyVoxCore/include/AmbientOcclusionCalculator.inl b/library/PolyVoxCore/include/AmbientOcclusionCalculator.inl
index 854663af..2fffd7e1 100644
--- a/library/PolyVoxCore/include/AmbientOcclusionCalculator.inl
+++ b/library/PolyVoxCore/include/AmbientOcclusionCalculator.inl
@@ -40,9 +40,9 @@ namespace PolyVox
 		,m_fRayLength(fRayLength)
 	{
 		//Make sure that the size of the volume is an exact multiple of the size of the array.
-		assert(m_volInput.getWidth() % arrayResult.getDimension(0) == 0);
-		assert(m_volInput.getHeight() % arrayResult.getDimension(1) == 0);
-		assert(m_volInput.getDepth() % arrayResult.getDimension(2) == 0);
+		assert(m_volInput->getWidth() % arrayResult->getDimension(0) == 0);
+		assert(m_volInput->getHeight() % arrayResult->getDimension(1) == 0);
+		assert(m_volInput->getDepth() % arrayResult->getDimension(2) == 0);
 
 		//Our initial indices. It doesn't matter exactly what we set here, but the code below makes 
 		//sure they are different for different regions which helps reduce tiling patterns is the results.
diff --git a/library/PolyVoxCore/include/SurfaceMesh.h b/library/PolyVoxCore/include/SurfaceMesh.h
index 7e94a8ae..82b1c1b7 100644
--- a/library/PolyVoxCore/include/SurfaceMesh.h
+++ b/library/PolyVoxCore/include/SurfaceMesh.h
@@ -93,6 +93,9 @@ namespace PolyVox
 		//exist on a material boundary do not count.
 		std::set<uint8_t> m_mapUsedMaterials;
 	};	
+
+	template <typename VertexType>
+	polyvox_shared_ptr< SurfaceMesh<VertexType> > extractSubset(SurfaceMesh<VertexType>& inputMesh, std::set<uint8_t> setMaterials);
 }
 
 #include "SurfaceMesh.inl"
diff --git a/library/PolyVoxCore/include/SurfaceMesh.inl b/library/PolyVoxCore/include/SurfaceMesh.inl
index 833a9f0b..47c39568 100644
--- a/library/PolyVoxCore/include/SurfaceMesh.inl
+++ b/library/PolyVoxCore/include/SurfaceMesh.inl
@@ -394,4 +394,71 @@ namespace PolyVox
 			m_vecTriangleIndices[triCt] = newPos[m_vecTriangleIndices[triCt]];
 		}
 	}
+
+	//Currently a free function - think where this needs to go.
+	template <typename VertexType>
+	polyvox_shared_ptr< SurfaceMesh<VertexType> > extractSubset(SurfaceMesh<VertexType>& inputMesh, std::set<uint8_t> setMaterials)
+	{
+		polyvox_shared_ptr< SurfaceMesh<VertexType> > result(new SurfaceMesh<VertexType>);
+
+		if(inputMesh.m_vecVertices.size() == 0) //FIXME - I don't think we should need this test, but I have seen crashes otherwise...
+		{
+			return result;
+		}
+
+		assert(inputMesh.m_vecLodRecords.size() == 1);
+		if(inputMesh.m_vecLodRecords.size() != 1)
+		{
+			//If we have done progressive LOD then it's too late to split into subsets.
+			return result;
+		}
+
+		std::vector<int32_t> indexMap(inputMesh.m_vecVertices.size());
+		std::fill(indexMap.begin(), indexMap.end(), -1);
+
+		for(uint32_t triCt = 0; triCt < inputMesh.m_vecTriangleIndices.size(); triCt += 3)
+		{
+
+			VertexType& v0 = inputMesh.m_vecVertices[inputMesh.m_vecTriangleIndices[triCt]];
+			VertexType& v1 = inputMesh.m_vecVertices[inputMesh.m_vecTriangleIndices[triCt + 1]];
+			VertexType& v2 = inputMesh.m_vecVertices[inputMesh.m_vecTriangleIndices[triCt + 2]];
+
+			if(
+				(setMaterials.find(v0.getMaterial()) != setMaterials.end()) || 
+				(setMaterials.find(v1.getMaterial()) != setMaterials.end()) || 
+				(setMaterials.find(v2.getMaterial()) != setMaterials.end()))
+			{
+				uint32_t i0;
+				if(indexMap[inputMesh.m_vecTriangleIndices[triCt]] == -1)
+				{
+					indexMap[inputMesh.m_vecTriangleIndices[triCt]] = result->addVertex(v0);
+				}
+				i0 = indexMap[inputMesh.m_vecTriangleIndices[triCt]];
+
+				uint32_t i1;
+				if(indexMap[inputMesh.m_vecTriangleIndices[triCt+1]] == -1)
+				{
+					indexMap[inputMesh.m_vecTriangleIndices[triCt+1]] = result->addVertex(v1);
+				}
+				i1 = indexMap[inputMesh.m_vecTriangleIndices[triCt+1]];
+
+				uint32_t i2;
+				if(indexMap[inputMesh.m_vecTriangleIndices[triCt+2]] == -1)
+				{
+					indexMap[inputMesh.m_vecTriangleIndices[triCt+2]] = result->addVertex(v2);
+				}
+				i2 = indexMap[inputMesh.m_vecTriangleIndices[triCt+2]];
+
+				result->addTriangle(i0,i1,i2);
+			}
+		}
+
+		result->m_vecLodRecords.clear();
+		LodRecord lodRecord;
+		lodRecord.beginIndex = 0;
+		lodRecord.endIndex = result->getNoOfIndices();
+		result->m_vecLodRecords.push_back(lodRecord);
+
+		return result;
+	}
 }