一.要點
繪製立方體(或其他3D圖形)的方法與繪製三角形的方法類似,任何一個3D圖形的輪廓都有一系列三角形構成.爲減少數據冗餘,在繪製複雜3D圖形時,應使用
GraphicsDevice.DrawIndexedPrimitives()方法，而不是繪製三角形時所使用的GraphicsDevice.DrawUserPrimitives()。
二.實現代碼
1.爲Game類添加成員變量:
1: VertexPositionColor[] vertexList;
2: VertexBuffer vertexBuffer;
3: ushort[] indexList;
4: IndexBuffer indexBuffer;
2.在LoadContent()方法中定義立方體六個頂點的座標
1: vertexList = new VertexPositionColor[]
2: {
3: new VertexPositionColor(new Vector3(1f,1f,-1f),Color.Red),
4: new VertexPositionColor(new Vector3(1f,-1f,-1f),Color.Red),
5: new VertexPositionColor(new Vector3(-1f,-1f,-1f),Color.Red),
6: new VertexPositionColor(new Vector3(-1f,1f,-1f),Color.Red),
7: new VertexPositionColor(new Vector3(1f,1f,1f),Color.Red),
8: new VertexPositionColor(new Vector3(1f,-1f,1f),Color.Red),
9: new VertexPositionColor(new Vector3(-1f,-1f,1f),Color.Red),
10: new VertexPositionColor(new Vector3(-1f,1f,1f),Color.Red)
11: };
12: vertexBuffer = new VertexBuffer(
13: GraphicsDevice,
14: typeof(VertexPositionColor),
15: vertexList.Length,
16: BufferUsage.None);
17: vertexBuffer.SetData<VertexPositionColor>(vertexList);
3.定義頂點索引數組：
1: indexList = new ushort[]
2: {
3: 0,1,2,0,2,3,
4: 7,4,5,7,5,6,
5: 0,1,5,0,5,4,
6: 7,3,2,7,2,6,
7: 0,4,7,0,7,3,
8: 2,1,5,2,5,6
9: };
10: indexBuffer = new IndexBuffer(
11: GraphicsDevice,
12: typeof(ushort),
13: indexList.Length,
14: BufferUsage.None);
15: indexBuffer.SetData<ushort>(indexList);
4.在Draw()方法中添加繪製代碼：
1: GraphicsDevice.SetVertexBuffer(vertexBuffer);
2: GraphicsDevice.Indices = indexBuffer;
3:
4: int primitiveCount = indexList.Length / 3;
5: foreach (var pass in basicEffect.CurrentTechnique.Passes)
6: {
7: pass.Apply();
8: GraphicsDevice.DrawIndexedPrimitives(
9: PrimitiveType.TriangleList,
10: 0,
11: 0,
12: vertexList.Length,
13: 0,
14: primitiveCount);
15: }
