From b990efce2400a3df8b4de46715e3bf2531e41572 Mon Sep 17 00:00:00 2001
From: David Williams <david@david-williams.info>
Date: Fri, 27 Jun 2008 16:44:18 +0000
Subject: [PATCH] Work on improving mesh decimation.

---
 PolyVoxCore/include/SurfaceAdjusters.h   |  1 +
 PolyVoxCore/source/SurfaceAdjusters.cpp  | 74 ++++++++++++++++++++++++
 PolyVoxCore/source/SurfaceExtractors.cpp | 10 +++-
 3 files changed, 83 insertions(+), 2 deletions(-)

diff --git a/PolyVoxCore/include/SurfaceAdjusters.h b/PolyVoxCore/include/SurfaceAdjusters.h
index e791af95..771b7c51 100644
--- a/PolyVoxCore/include/SurfaceAdjusters.h
+++ b/PolyVoxCore/include/SurfaceAdjusters.h
@@ -33,6 +33,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 namespace PolyVox
 {
 	POLYVOX_API void smoothRegionGeometry(BlockVolume<std::uint8_t>* volumeData, RegionGeometry& regGeom);
+	POLYVOX_API void adjustDecimatedGeometry(BlockVolume<std::uint8_t>* volumeData, RegionGeometry& regGeom, std::uint8_t val);
 }
 
 #endif
\ No newline at end of file
diff --git a/PolyVoxCore/source/SurfaceAdjusters.cpp b/PolyVoxCore/source/SurfaceAdjusters.cpp
index e82caf57..2982f64a 100644
--- a/PolyVoxCore/source/SurfaceAdjusters.cpp
+++ b/PolyVoxCore/source/SurfaceAdjusters.cpp
@@ -9,6 +9,8 @@
 
 #include <vector>
 
+using namespace std;
+
 namespace PolyVox
 {
 	void smoothRegionGeometry(BlockVolume<std::uint8_t>* volumeData, RegionGeometry& regGeom)
@@ -74,4 +76,76 @@ namespace PolyVox
 			++iterSurfaceVertex;
 		} //while(iterSurfaceVertex != vecVertices.end())
 	}
+
+	void adjustDecimatedGeometry(BlockVolume<std::uint8_t>* volumeData, RegionGeometry& regGeom, uint8_t val)
+	{
+		BlockVolumeIterator<std::uint8_t> volIter(*volumeData);
+
+		std::vector<SurfaceVertex>& vecVertices = regGeom.m_patchSingleMaterial->m_vecVertices;
+		std::vector<SurfaceVertex>::iterator iterSurfaceVertex = vecVertices.begin();
+		while(iterSurfaceVertex != vecVertices.end())
+		{
+			Vector3DFloat v3dPos = iterSurfaceVertex->getPosition() + static_cast<Vector3DFloat>(regGeom.m_v3dRegionPosition);
+			Vector3DInt32 v3dFloor = static_cast<Vector3DInt32>(v3dPos);
+
+			BlockVolumeIterator<std::uint8_t> volIter(*volumeData);
+
+			//Check all corners are within the volume, allowing a boundary for gradient estimation
+			bool lowerCornerInside = volumeData->containsPoint(v3dFloor,1);
+			bool upperCornerInside = volumeData->containsPoint(v3dFloor+Vector3DInt32(1,1,1),1);
+
+			if(lowerCornerInside && upperCornerInside) //If this test fails the vertex will be left as it was
+			{				
+				//volIter.setPosition(static_cast<Vector3DInt16>(v3dFloor));
+				//const uint8_t uFloor = volIter.getVoxel();
+				if(((v3dPos.getX() - v3dFloor.getX()) < 0.001) && ((v3dPos.getY() - v3dFloor.getY()) < 0.001) && ((v3dPos.getZ() - v3dFloor.getZ()) < 0.001))
+				//int x = v3dPos.getX();
+				//if(x % 2 != 0)
+				//if((iterSurfaceVertex->getNormal().getX() > 0.5f) || (iterSurfaceVertex->getNormal().getX() < -0.5f))
+				{	
+					//exit(0);
+					//volIter.setPosition(static_cast<Vector3DInt16>(v3dFloor+Vector3DInt32(1,0,0)));
+					//const uint8_t uCeil = volIter.getVoxel();
+					//if(uFloor == uCeil) //In this case they must both be zero
+					{						
+						//if(iterSurfaceVertex->getNormal().getX() > 0)
+						{
+							iterSurfaceVertex->setPosition(iterSurfaceVertex->getPosition() - iterSurfaceVertex->getNormal() * 0.5f);
+							v3dPos = iterSurfaceVertex->getPosition() + static_cast<Vector3DFloat>(regGeom.m_v3dRegionPosition);
+							v3dFloor = static_cast<Vector3DInt32>(v3dPos);
+
+							volIter.setPosition(static_cast<Vector3DInt16>(v3dFloor));
+							const uint8_t uFloor = volIter.getVoxel();
+
+							uint8_t uCeil;
+							if((iterSurfaceVertex->getNormal().getX() > 0.5f) || (iterSurfaceVertex->getNormal().getX() < -0.5f))
+							{
+								volIter.setPosition(static_cast<Vector3DInt16>(v3dFloor+Vector3DInt32(1,0,0)));
+								uCeil = volIter.getVoxel();
+							}
+							if((iterSurfaceVertex->getNormal().getY() > 0.5f) || (iterSurfaceVertex->getNormal().getY() < -0.5f))
+							{
+								volIter.setPosition(static_cast<Vector3DInt16>(v3dFloor+Vector3DInt32(0,1,0)));
+								uCeil = volIter.getVoxel();
+							}
+							if((iterSurfaceVertex->getNormal().getZ() > 0.5f) || (iterSurfaceVertex->getNormal().getZ() < -0.5f))
+							{
+								volIter.setPosition(static_cast<Vector3DInt16>(v3dFloor+Vector3DInt32(0,0,1)));
+								uCeil = volIter.getVoxel();
+							}
+
+							if(uFloor == uCeil)
+							{
+								//NOTE: The normal should actually be multiplied by 1.0f. This works 
+								//for the simple cube but causes depth fighting on more complex shapes.
+								iterSurfaceVertex->setPosition(iterSurfaceVertex->getPosition() - iterSurfaceVertex->getNormal() * 0.5f);
+							}
+						}
+					}
+				}
+			}
+
+			++iterSurfaceVertex;
+		} //while(iterSurfaceVertex != vecVertices.end())
+	}
 }
\ No newline at end of file
diff --git a/PolyVoxCore/source/SurfaceExtractors.cpp b/PolyVoxCore/source/SurfaceExtractors.cpp
index f8a31ff4..9f40b119 100644
--- a/PolyVoxCore/source/SurfaceExtractors.cpp
+++ b/PolyVoxCore/source/SurfaceExtractors.cpp
@@ -37,9 +37,15 @@ namespace PolyVox
 			//for(int ct = 0; ct < 2; ct++)
 			Vector3DInt32 temp = regionGeometry.m_v3dRegionPosition;
 			//temp /= 16;
-			if(temp.getX() % 32 == 0)
+			if(temp.getY() % 32 == 0)
 			{
-				smoothRegionGeometry(volume.getVolumeData(), regionGeometry);
+				//smoothRegionGeometry(volume.getVolumeData(), regionGeometry);
+				generateDecimatedMeshDataForRegion(volume.getVolumeData(), 0, *iterChangedRegions, regionGeometry.m_patchSingleMaterial);
+			}
+			else
+			{
+				generateDecimatedMeshDataForRegion(volume.getVolumeData(), 1, *iterChangedRegions, regionGeometry.m_patchSingleMaterial);
+				//adjustDecimatedGeometry(volume.getVolumeData(), regionGeometry, 1);
 			}
 
 			//computeNormalsForVertices(volume.getVolumeData(), regionGeometry, CENTRAL_DIFFERENCE);