From e51b9cfee9a88f0028eca1866d7540050244c573 Mon Sep 17 00:00:00 2001
From: David Williams <david@david-williams.info>
Date: Sat, 27 Jun 2009 19:11:33 +0000
Subject: [PATCH] Work on improving material system.

---
 .../PolyVoxCore/include/IndexedSurfacePatch.h |  4 ++-
 .../source/IndexedSurfacePatch.cpp            | 34 +++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/library/PolyVoxCore/include/IndexedSurfacePatch.h b/library/PolyVoxCore/include/IndexedSurfacePatch.h
index 06061e49..420511d9 100644
--- a/library/PolyVoxCore/include/IndexedSurfacePatch.h
+++ b/library/PolyVoxCore/include/IndexedSurfacePatch.h
@@ -23,6 +23,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #define __PolyVox_IndexedSurfacePatch_H__
 
 #include <vector>
+#include <set>
 
 #include "PolyVoxImpl/CPlusPlusZeroXSupport.h"
 
@@ -54,6 +55,8 @@ namespace PolyVox
 
 	   void smooth(float fAmount, bool bIncludeEdgeVertices = false);
 
+	   POLYVOX_SHARED_PTR<IndexedSurfacePatch> extractSubset(std::set<uint8_t> setMaterials);
+
 	   void generateAveragedFaceNormals(bool bNormalise, bool bIncludeEdgeVertices = false);
 
 	   //Vector3DInt32 m_v3dRegionPosition; //FIXME - remove this?
@@ -66,7 +69,6 @@ namespace PolyVox
 		std::vector<uint32_t> m_vecTriangleIndices;
 		std::vector<SurfaceVertex> m_vecVertices;
 	};	
-
 }
 
 #endif /* __IndexedSurfacePatch_H__ */
diff --git a/library/PolyVoxCore/source/IndexedSurfacePatch.cpp b/library/PolyVoxCore/source/IndexedSurfacePatch.cpp
index 3cb2cb52..5e52ec1d 100644
--- a/library/PolyVoxCore/source/IndexedSurfacePatch.cpp
+++ b/library/PolyVoxCore/source/IndexedSurfacePatch.cpp
@@ -218,4 +218,38 @@ namespace PolyVox
 			}
 		}
 	}
+
+	POLYVOX_SHARED_PTR<IndexedSurfacePatch> IndexedSurfacePatch::extractSubset(std::set<uint8_t> setMaterials)
+	{
+		POLYVOX_SHARED_PTR<IndexedSurfacePatch> result(new IndexedSurfacePatch);
+
+		if(m_vecVertices.size() == 0) //FIXME - I don't think we should need this test, but I have seen crashes otherwise...
+		{
+			return result;
+		}
+
+		for(vector<uint32_t>::iterator iterIndex = m_vecTriangleIndices.begin(); iterIndex != m_vecTriangleIndices.end();)
+		{
+			SurfaceVertex& v0 = m_vecVertices[*iterIndex];
+			iterIndex++;
+			SurfaceVertex& v1 = m_vecVertices[*iterIndex];
+			iterIndex++;
+			SurfaceVertex& v2 = m_vecVertices[*iterIndex];
+			iterIndex++;
+
+			if(
+				(setMaterials.find(v0.getMaterial()) != setMaterials.end()) || 
+				(setMaterials.find(v1.getMaterial()) != setMaterials.end()) || 
+				(setMaterials.find(v2.getMaterial()) != setMaterials.end()))
+			{
+				uint32_t i0 = result->addVertex(v0);
+				uint32_t i1 = result->addVertex(v1);
+				uint32_t i2 = result->addVertex(v2);
+
+				result->addTriangle(i0,i1,i2);
+			}
+		}
+
+		return result;
+	}
 }