1 files changed, 104 insertions, 0 deletions
diff --git a/tier2/meshutils.cpp b/tier2/meshutils.cpp
new file mode 100644
index 0000000..4aa0144
--- /dev/null
+++ b/tier2/meshutils.cpp
@@ -0,0 +1,104 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: A set of utilities to render standard shapes
+//
+//===========================================================================//
+
+#include "tier2/meshutils.h"
+
+
+//-----------------------------------------------------------------------------
+// Helper methods to create various standard index buffer types
+//-----------------------------------------------------------------------------
+void GenerateSequentialIndexBuffer( unsigned short* pIndices, int nIndexCount, int nFirstVertex )
+{
+	if ( !pIndices )
+		return;
+
+	// Format the sequential buffer
+	for ( int i = 0; i < nIndexCount; ++i )
+	{
+		pIndices[i] = (unsigned short)( i + nFirstVertex );
+	}
+}
+
+void GenerateQuadIndexBuffer( unsigned short* pIndices, int nIndexCount, int nFirstVertex )
+{
+	if ( !pIndices )
+		return;
+
+	// Format the quad buffer
+	int i;
+	int numQuads = nIndexCount / 6;
+	int baseVertex = nFirstVertex;
+	for ( i = 0; i < numQuads; ++i)
+	{
+		// Triangle 1
+		pIndices[0] = (unsigned short)( baseVertex );
+		pIndices[1] = (unsigned short)( baseVertex + 1 );
+		pIndices[2] = (unsigned short)( baseVertex + 2 );
+
+		// Triangle 2
+		pIndices[3] = (unsigned short)( baseVertex );
+		pIndices[4] = (unsigned short)( baseVertex + 2 );
+		pIndices[5] = (unsigned short)( baseVertex + 3 );
+
+		baseVertex += 4;
+		pIndices += 6;
+	}
+}
+
+void GeneratePolygonIndexBuffer( unsigned short* pIndices, int nIndexCount, int nFirstVertex )
+{
+	if ( !pIndices )
+		return;
+
+	int i;
+	int numPolygons = nIndexCount / 3;
+	for ( i = 0; i < numPolygons; ++i)
+	{
+		// Triangle 1
+		pIndices[0] = (unsigned short)( nFirstVertex );
+		pIndices[1] = (unsigned short)( nFirstVertex + i + 1 );
+		pIndices[2] = (unsigned short)( nFirstVertex + i + 2 );
+		pIndices += 3;
+	}
+}
+
+
+void GenerateLineStripIndexBuffer( unsigned short* pIndices, int nIndexCount, int nFirstVertex )
+{
+	if ( !pIndices )
+		return;
+
+	int i;
+	int numLines = nIndexCount / 2;
+	for ( i = 0; i < numLines; ++i)
+	{
+		pIndices[0] = (unsigned short)( nFirstVertex + i );
+		pIndices[1] = (unsigned short)( nFirstVertex + i + 1 );
+		pIndices += 2;
+	}
+}
+
+void GenerateLineLoopIndexBuffer( unsigned short* pIndices, int nIndexCount, int nFirstVertex )
+{
+	if ( !pIndices )
+	{
+		return;
+	}
+
+	int i;
+	int numLines = nIndexCount / 2;
+
+	pIndices[0] = (unsigned short)( nFirstVertex + numLines - 1 );
+	pIndices[1] = (unsigned short)( nFirstVertex );
+	pIndices += 2;
+
+	for ( i = 1; i < numLines; ++i)
+	{
+		pIndices[0] = (unsigned short)( nFirstVertex + i - 1 );
+		pIndices[1] = (unsigned short)( nFirstVertex + i );
+		pIndices += 2;
+	}
+}