c# - 重用顶点传递到着色器

Question

一般问题：

假设您有一个顶点列表，您可以根据着色器参数（例如，激光宽度或其他）传递给效果以绘制某些东西。我想传递相同的顶点，但使用不同的着色器参数 - 但是，这不起作用。

这是有问题的代码：

           foreach (EffectPass pass in quinticFX.CurrentTechnique.Passes)
            {
                quinticFX.Parameters["NumPoints"].SetValue(CurvedVertices.Count());
                pass.Apply();
                GraphicsDevice.SamplerStates[0] = LinearMirrorState;
                GraphicsDevice.Textures[0] = solid;

                quinticFX.Parameters["radiusOfBeam"].SetValue(8);
                GraphicsDevice.DrawUserPrimitives<VertexPositionTexture>(PrimitiveType.TriangleStrip, CurvedVertices.ToArray(), 0, CurvedVertices.Count() - 2);
                pass.Apply();

                quinticFX.Parameters["radiusOfBeam"].SetValue(4);
                quinticFX.Parameters["P"].SetValue(cp1);
                GraphicsDevice.DrawUserPrimitives<VertexPositionTexture>(PrimitiveType.TriangleStrip, CurvedVertices.ToArray(), 0, CurvedVertices .Count() - 2);
            }

我假设你可以这样做，它会用不同的控制点和宽度绘制（在本例中为曲线）两次。情况并非如此——仅绘制最近的一组图元。任何帮助将不胜感激。

Answer 1

原来我是个白痴——设置参数后需要 Apply() 通行证。

修正后的代码如下：

foreach (EffectPass pass in quinticFX.CurrentTechnique.Passes)
{
    quinticFX.Parameters["NumPoints"].SetValue(CurvedVertices.Count());
    //GraphicsDevice.SamplerStates[0] = SamplerState.LinearWrap;
    GraphicsDevice.SamplerStates[0] = LinearMirrorState;
    GraphicsDevice.Textures[0] = solid;

    quinticFX.Parameters["radiusOfBeam"].SetValue(12);
    pass.Apply();
    GraphicsDevice.DrawUserPrimitives<VertexPositionTexture>(PrimitiveType.TriangleStrip, CurvedVertices.ToArray(), 0, CurvedVertices.Count() - 2);

    quinticFX.Parameters["radiusOfBeam"].SetValue(6);
    quinticFX.Parameters["P"].SetValue(cp1);
    pass.Apply();
    GraphicsDevice.DrawUserPrimitives<VertexPositionTexture>(PrimitiveType.TriangleStrip, CurvedVertices.ToArray(), 0, CurvedVertices.Count() - 2);

    quinticFX.Parameters["radiusOfBeam"].SetValue(3);
    quinticFX.Parameters["P"].SetValue(cp2);
    pass.Apply();
    GraphicsDevice.DrawUserPrimitives<VertexPositionTexture>(PrimitiveType.TriangleStrip, CurvedVertices.ToArray(), 0, CurvedVertices.Count() - 2);
}