From 15740faf9fe9fe4be08965098bbf2947e096aeeb Mon Sep 17 00:00:00 2001
From: chai <chaifix@163.com>
Date: Wed, 14 Aug 2019 22:50:43 +0800
Subject: +Unity Runtime code

---
 Runtime/Terrain/TerrainIndexGenerator.cpp | 379 ++++++++++++++++++++++++++++++
 1 file changed, 379 insertions(+)
 create mode 100644 Runtime/Terrain/TerrainIndexGenerator.cpp

(limited to 'Runtime/Terrain/TerrainIndexGenerator.cpp')

diff --git a/Runtime/Terrain/TerrainIndexGenerator.cpp b/Runtime/Terrain/TerrainIndexGenerator.cpp
new file mode 100644
index 0000000..bcbc8d3
--- /dev/null
+++ b/Runtime/Terrain/TerrainIndexGenerator.cpp
@@ -0,0 +1,379 @@
+#include "UnityPrefix.h"
+#include "TerrainIndexGenerator.h"
+
+#if ENABLE_TERRAIN
+
+#include "Runtime/Graphics/TriStripper.h"
+#include "Runtime/Filters/Mesh/LodMesh.h"
+#include "Runtime/Terrain/Heightmap.h"
+
+static unsigned int AddSliverTriangles (unsigned int *triangles, unsigned int index, int direction, int edgeMask);
+static unsigned int AddSliverCorner (unsigned int* triangles, unsigned int index, int direction, int edgeMask);
+static void FlipTriangle (unsigned int *triangles, unsigned int index);
+static unsigned int AddQuad (unsigned int *triangles, unsigned int index, int xBase, int yBase);
+
+
+struct CachedStrip {
+	unsigned int count;
+	unsigned short* triangles;
+	
+	CachedStrip() {count = 0; triangles = NULL;}
+	~CachedStrip() { if(triangles) delete[] triangles;}
+};
+
+static CachedStrip gCachedStrips[16];
+
+unsigned int *TerrainIndexGenerator::GetIndexBuffer (int edgeMask, unsigned int &count, int stride)
+{
+	unsigned int *triangles = new unsigned int[(kPatchSize) * (kPatchSize) * 6];
+	unsigned int index = 0;
+	int size = kPatchSize;
+	
+	int minX = 0;
+	int minY = 0;
+	int maxX = kPatchSize-1;
+	int maxY = kPatchSize-1;
+	
+	if((edgeMask & kDirectionLeftFlag) == 0)
+	{
+		minX+=1;
+		index = AddSliverTriangles (triangles, index, kDirectionLeft, edgeMask);
+	}
+	if((edgeMask & kDirectionRightFlag) == 0)
+	{
+		maxX-=1;
+		index = AddSliverTriangles (triangles, index, kDirectionRight, edgeMask);
+	}
+	if((edgeMask & kDirectionUpFlag) == 0)
+	{
+		maxY-=1;
+		index = AddSliverTriangles (triangles, index, kDirectionUp, edgeMask);
+	}
+	if((edgeMask & kDirectionDownFlag) == 0)
+	{
+		minY+=1;
+		index = AddSliverTriangles (triangles, index, kDirectionDown, edgeMask);
+	}
+
+	if((edgeMask & kDirectionLeftFlag) == 0 || (edgeMask & kDirectionUpFlag) == 0)
+		index = AddSliverCorner (triangles, index, kDirectionLeftUp, edgeMask);
+	if((edgeMask & kDirectionRightFlag) == 0 || (edgeMask & kDirectionUpFlag) == 0)
+		index = AddSliverCorner (triangles, index, kDirectionRightUp, edgeMask);
+	if((edgeMask & kDirectionLeftFlag) == 0 || (edgeMask & kDirectionDownFlag) == 0)
+		index = AddSliverCorner (triangles, index, kDirectionLeftDown, edgeMask);
+	if((edgeMask & kDirectionRightFlag) == 0 || (edgeMask & kDirectionDownFlag) == 0)
+		index = AddSliverCorner (triangles, index, kDirectionRightDown, edgeMask);
+	
+	for (int y=minY;y<maxY;y++)
+	{
+		for (int x=minX;x<maxX;x++)
+		{
+			// For each grid cell output two triangles
+			triangles[index++] = y     + (x * size);
+			triangles[index++] = (y+1) + x * size;
+			triangles[index++] = (y+1) + (x + 1) * size;
+
+			triangles[index++] = y     + x * size;
+			triangles[index++] = (y+1) + (x + 1) * size;
+			triangles[index++] = y     + (x + 1) * size;
+		}
+	}
+	
+	count = index;		
+	return triangles;
+}
+
+unsigned short *TerrainIndexGenerator::GetOptimizedIndexStrip (int edgeMask, unsigned int &count)
+{
+	edgeMask &= kDirectionDirectNeighbourMask;
+	if (gCachedStrips[edgeMask].triangles == NULL)
+	{
+		unsigned int *triangles = GetIndexBuffer (edgeMask, count, 0);
+		
+		Mesh::TemporaryIndexContainer newStrip;
+
+		Stripify ((const UInt32*)triangles, count, newStrip);
+		
+		delete[] triangles;
+		
+		count = newStrip.size();
+		unsigned short *strip = new unsigned short[count];
+		for(int i=0;i<count;i++)
+			strip[i] = newStrip[i];
+		gCachedStrips[edgeMask].count = count;
+		gCachedStrips[edgeMask].triangles = strip;
+	}
+	
+	count = gCachedStrips[edgeMask].count;
+	return gCachedStrips[edgeMask].triangles;
+}
+
+static void FlipTriangle (unsigned int *triangles, unsigned int index)
+{
+	int temp = triangles[index];
+	triangles[index] = triangles[index+1];
+	triangles[index+1] = temp;
+}
+	
+static unsigned int AddQuad (unsigned int *triangles, unsigned int index, int xBase, int yBase)
+{
+	triangles[index++] = (xBase +  0) * kPatchSize + (yBase + 0);
+	triangles[index++] = (xBase +  0) * kPatchSize + (yBase + 1);
+	triangles[index++] = (xBase +  1) * kPatchSize + (yBase + 1);
+
+	triangles[index++] = (xBase +  0) * kPatchSize + (yBase + 0);
+	triangles[index++] = (xBase +  1) * kPatchSize + (yBase + 1);
+	triangles[index++] = (xBase +  1) * kPatchSize + (yBase + 0);
+	
+	return index;
+}
+	
+static unsigned int AddSliverCorner (unsigned int* triangles, unsigned int index, int direction, int edgeMask)
+{
+	int xBase, yBase, ox, oy;
+	bool flip = false;
+	
+	int vMask = 0;
+	int hMask = 0;
+
+	if (direction == kDirectionLeftDown)
+	{
+		xBase = 1;
+		yBase = 1;
+		ox = 1;
+		oy = 1;
+		flip = false;
+
+		hMask = 1 << kDirectionLeft;
+		vMask = 1 << kDirectionDown;
+	}
+	else if (direction == kDirectionRightDown)
+	{
+		xBase = kPatchSize-2;
+		yBase = 1;
+		ox = -1;
+		oy = 1;
+		flip = true;
+
+		hMask = 1 << kDirectionRight;
+		vMask = 1 << kDirectionDown;
+	}
+	else if (direction == kDirectionLeftUp)
+	{
+		xBase = 1;
+		yBase = kPatchSize-2;
+		ox = 1;
+		oy = -1;
+		flip = true;
+
+		hMask = 1 << kDirectionLeft;
+		vMask = 1 << kDirectionUp;
+	}
+	else
+	{
+		xBase = kPatchSize-2;
+		yBase = kPatchSize-2;
+		ox = -1;
+		oy = -1;
+		flip = false;
+
+		hMask = 1 << kDirectionRight;
+		vMask = 1 << kDirectionUp;
+	}
+
+	int mask = 0;
+	if ((hMask & edgeMask) != 0)
+		mask |= 1;
+	if ((vMask & edgeMask) != 0)
+		mask |= 2;
+
+	// Both edges are tesselated
+	// Vertical edge is tesselated
+	if (mask == 1)
+	{
+		// Stitch big down and small up
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase + 0);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase - oy);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase + 0);
+		
+		// rigth up small
+		triangles[index++] = (xBase +  ox) * kPatchSize + (yBase - oy);
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase +  ox) * kPatchSize + (yBase + 0);
+		
+		// Down Big span
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase +  ox) * kPatchSize + (yBase - oy);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase - oy);
+		
+		if (flip)
+		{
+			FlipTriangle(triangles, index - 9);
+			FlipTriangle(triangles, index - 6);
+			FlipTriangle(triangles, index - 3);
+		}
+
+	}
+	// Horizontal edge is tesselated
+	else if (mask == 2)
+	{
+		// Left up small
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase + oy);
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase + oy);
+
+		// Left Big span
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase - oy);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase + oy);
+
+		// Stitch right-down and big left span
+		triangles[index++] = (xBase - ox) * kPatchSize + (yBase - oy);
+		triangles[index++] = (xBase +  0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase +  0) * kPatchSize + (yBase - oy);
+		
+		if (flip)
+		{
+			FlipTriangle(triangles, index - 9);
+			FlipTriangle(triangles, index - 6);
+			FlipTriangle(triangles, index - 3);
+		}
+
+	}
+	// Nothing tesselated
+	else
+	{
+		// Left up small
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase + oy);
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase + oy);
+		// right up small
+		triangles[index++] = (xBase +  ox) * kPatchSize + (yBase - oy);
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase +  ox) * kPatchSize + (yBase + 0);
+		// Left Big span
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase - oy);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase + oy);
+		// Down Big span
+		triangles[index++] = (xBase +   0) * kPatchSize + (yBase +  0);
+		triangles[index++] = (xBase +  ox) * kPatchSize + (yBase - oy);
+		triangles[index++] = (xBase -  ox) * kPatchSize + (yBase - oy);
+		
+		if (flip)
+		{
+			FlipTriangle(triangles, index - 12);
+			FlipTriangle(triangles, index - 9);
+			FlipTriangle(triangles, index - 6);
+			FlipTriangle(triangles, index - 3);
+		}
+	}
+
+	return index;		
+}
+		
+static unsigned int AddSliverTriangles (unsigned int *triangles, unsigned int index, int direction, int edgeMask)
+{
+	int directionMask = 1 << direction;
+	if ((edgeMask & directionMask) != 0)
+	{
+		for (int y=2;y<kPatchSize-3;y++)
+		{
+			if (direction == kDirectionLeft)
+				index = AddQuad(triangles, index, 0, y);	
+			else if (direction == kDirectionRight)
+				index = AddQuad(triangles, index, kPatchSize - 2, y);	
+			else if (direction == kDirectionUp)
+				index = AddQuad(triangles, index, y, kPatchSize - 2);	
+			else if (direction == kDirectionDown)
+				index = AddQuad(triangles, index, y, 0);	
+		}
+	}
+	else
+	{
+		for (int i=2;i<kPatchSize-3;i+=2)
+		{
+			if (direction == kDirectionLeft)
+			{
+				int x = 0;
+				int y = i;
+
+				// fixup bottom
+				triangles[index++] = (x +  1) * kPatchSize + (y + 0);
+				triangles[index++] = (x +  0) * kPatchSize + (y +  0);
+				triangles[index++] = (x +  1) * kPatchSize + (y + 1);
+				
+				// Big span
+				triangles[index++] = (x +   0) * kPatchSize + (y +  0);
+				triangles[index++] = (x +   0) * kPatchSize + (y +  2);
+				triangles[index++] = (x +   1) * kPatchSize + (y +  1);
+
+				// fixup top
+				triangles[index++] = (x +   0) * kPatchSize + (y +  2);
+				triangles[index++] = (x +   1) * kPatchSize + (y +  2);
+				triangles[index++] = (x +   1) * kPatchSize + (y + 1);
+			}
+			else if (direction == kDirectionRight)
+			{
+				int x = kPatchSize - 1;
+				int y = i;
+				
+				// fixup bottom
+				triangles[index++] = (x -  1) * kPatchSize + (y + 0);
+				triangles[index++] = (x -  1) * kPatchSize + (y + 1);
+				triangles[index++] = (x -   0) * kPatchSize + (y +  0);
+				
+				// Big span
+				triangles[index++] = (x -   0) * kPatchSize + (y +  0);
+				triangles[index++] = (x -   1) * kPatchSize + (y +  1);
+				triangles[index++] = (x -   0) * kPatchSize + (y +  2);
+
+				// fixup top
+				triangles[index++] = (x -   0) * kPatchSize + (y +  2);
+				triangles[index++] = (x -  1) * kPatchSize + (y + 1);
+				triangles[index++] = (x -  1) * kPatchSize + (y +  2);
+			}				
+			else if (direction == kDirectionDown)
+			{
+				int x = i;
+				int y = 0;
+
+				// fixup bottom
+				triangles[index++] = (x +  0) * kPatchSize + (y + 0);
+				triangles[index++] = (x +  0) * kPatchSize + (y +  1);
+				triangles[index++] = (x +  1) * kPatchSize + (y + 1);
+				
+				// Big span
+				triangles[index++] = (x +  1) * kPatchSize + (y + 1);
+				triangles[index++] = (x +  2) * kPatchSize + (y +  0);
+				triangles[index++] = (x +  0) * kPatchSize + (y +  0);
+				// fixup top
+				triangles[index++] = (x +  2) * kPatchSize + (y +  0);
+				triangles[index++] = (x +  1) * kPatchSize + (y +  1);
+				triangles[index++] = (x +  2) * kPatchSize + (y +  1);
+			}
+			else
+			{
+				int x = i;
+				int y = kPatchSize - 1;
+
+				// fixup bottom
+				triangles[index++] = (x +  0) * kPatchSize + (y - 0);
+				triangles[index++] = (x +  1) * kPatchSize + (y - 1);
+				triangles[index++] = (x +  0) * kPatchSize + (y -  1);
+				
+				// Big span
+				triangles[index++] = (x +  1) * kPatchSize + (y - 1);
+				triangles[index++] = (x +  0) * kPatchSize + (y -  0);
+				triangles[index++] = (x +  2) * kPatchSize + (y -  0);
+				// fixup top
+				triangles[index++] = (x +  2) * kPatchSize + (y -  0);
+				triangles[index++] = (x +  2) * kPatchSize + (y -  1);
+				triangles[index++] = (x +  1) * kPatchSize + (y -  1);
+			}
+		}
+	}
+	return index;
+}
+
+#endif // ENABLE_TERRAIN
-- 
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