/// <summary>
///
/// </summary>
/// <typeparam name="T">The type of the vertices</typeparam>
/// <param name="primitiveT">The type of primitives to draw with the vertices</param>
/// <param name="vertexData">An array of vertices to draw</param>
/// <param name="vertexOffset">The index in the array of the first vertex to draw</param>
/// <param name="numVertices">The number of vertices to draw</param>
/// <param name="indexData">The index data</param>
/// <param name="indexOffset">The index in the array of indices of the first index to use</param>
/// <param name="primitiveCount">The number of primitives to draw</param>
/// <param name="vertexDeclaration">The layout of the vertices</param>
public void DrawUserIndexedPrimitives <T>(PrimitiveType primitiveT, T[] vertexData, int vertexOffset,
int numVertices, short[] indexData, int indexOffset, int primitiveCount, VertexDeclaration vertexDeclaration) where T : struct
{
if (vertexData == null || vertexData.Length == 0)
{
throw new ArgumentNullException("vertexData");
}
if (vertexOffset < 0 || vertexOffset >= vertexData.Length)
{
throw new ArgumentNullException("vertexOffset");
}
if (numVertices <= 0 || numVertices > vertexData.Length)
{
throw new ArgumentNullException("numVertices");
}
if (vertexOffset + numVertices > vertexData.Length)
{
throw new ArgumentOutOfRangeException("numVertices & vertexOffset out of index");
}
if (indexData == null || indexData.Length == 0)
{
throw new ArgumentNullException("indexData");
}
if (indexOffset < 0 || indexOffset >= indexData.Length)
{
throw new ArgumentOutOfRangeException("indexOffset");
}
if (primitiveCount <= 0)
{
throw new ArgumentOutOfRangeException("primitiveCount");
}
if (indexOffset + GetElementCountArray(primitiveT, primitiveCount) > indexData.Length)
{
throw new ArgumentOutOfRangeException("primitiveCount");
}
if (vertexDeclaration == null)
{
throw new ArgumentNullException("vertexDeclaration");
}
PlatformDrawUserIndexedPrimitives <T>(primitiveT, vertexData, vertexOffset, numVertices, indexData, indexOffset, primitiveCount, vertexDeclaration);
unchecked
{
_graphicsMetrics._drawCount++;
_graphicsMetrics._primitiveCount += primitiveCount;
}
}
private void PlatformDrawUserIndexedPrimitives <T>(PrimitiveType primitiveT, T[] vertexData, int vertexOffset, int numVertices, short[] indexData, int indexOffset, int primitiveCount, VertexDeclaration vertexDeclaration)
{
ApplyState(true);
//Unbind current VBOs
GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
GraphicsExtensions.CheckGLError();
GL.BindBuffer(BufferTarget.ElementArrayBuffer, 0);
GraphicsExtensions.CheckGLError();
_vertexBuffersDirty = _indexBufferDirty = true;
//固定对象的地址，这样可以防止垃圾回收器移动对象，从而破坏垃圾收集器的效率，使用Free方法尽快释放分配的句柄
var vbHandle = GCHandle.Alloc(vertexData, GCHandleType.Pinned);
var ibHandle = GCHandle.Alloc(indexData, GCHandleType.Pinned);
var vertexAddr = (IntPtr)(vbHandle.AddrOfPinnedObject().ToInt64() + vertexDeclaration.VertexStride * vertexOffset);
vertexDeclaration.GraphicsDevice = this;
//设置顶点声明指向VertexBuffer Data
var programHash = _vertexShader.HashKey | _pixelShader.HashKey;
vertexDeclaration.Apply(_vertexShader, vertexAddr, programHash);
GL.DrawElements(PrimitiveTypeGL(primitiveT),
GetElementCountArray(primitiveT, primitiveCount),
DrawElementsType.UnsignedShort,
(IntPtr)(ibHandle.AddrOfPinnedObject().ToInt64() + (indexOffset * sizeof(short))));
GraphicsExtensions.CheckGLError();
//Release Handle
ibHandle.Free();
vbHandle.Free();
}
