drawVisualizationFrame
fun DrawScope.drawVisualizationFrame(visualization: Visualization, state: VizRenderState, previous: ImageBitmap?)
The echo layer of one frame, on a transparent bitmap: the frame before it faded and moved, then the new drawing. Pass the bitmap from the frame before as previous.
Public because offscreen rendering has to produce the same picture the window does. Lay the result over the rest with drawComposedFrame.