| src | The source GraphicsBuffer. |
| dst | The destination GraphicsBuffer. |
| dstOffsetBytes | The destination buffer offset in bytes. |
Copy the counter value of a GraphicsBuffer into another buffer.
Append/consume buffers (see GraphicsBuffer.Target.Append and counter buffers GraphicsBuffer.Target.Counter) keep track of the number of elements in them with a special counter variable. CopyCount takes such a buffer as src, and copies its counter value into dst buffer at given byte offset.
This is most commonly used in conjunction with Graphics.RenderPrimitivesIndirect, to render an arbitrary number of primitives without reading their count back to the CPU.
The src buffer must have been created with a usage target of GraphicsBuffer.Target.Append or GraphicsBuffer.Target.Counter.
On DirectX 11 and 12, the dst buffer must have been created with a usage target of GraphicsBuffer.Target.Raw or GraphicsBuffer.Target.IndirectArguments. For other graphics APIs, there is no such restriction.
另请参阅：SetCounterValue。