Starts a render that records in time slices and draws on the GPU when the recording completes.
public WebGLRender BeginRender(DisplayList list, Bitmap target, in Matrix deviceTransform, bool readBack, CancellationToken cancellationToken)
The display list.
The pixels, holding a uniform background on entry (white paper, or transparent).
Default user space to the target's pixels.
Whether the GPU's pixels are copied into target; when false they stay in Canvas until the next
render (unless IsInCanvas is false: the software rasterizer drew the render into the target).
Stops the render.