The VDP implementation of openMSX certainly knows the current pixel being drawn by the rasterizer at a given moment. It would be useful to have an overlay (a toggle, like toggle_scc_viewer) to show the coordinates of the pixel currently being drawn by the VDP.
Due to the speed, this overlay will of course only be useful when running openMSX on step-by-step while debugging. This will help the programmer to:
- Know when certain events will be triggered (vblank interrupt, line interrupt)
- Debug why a sprite drawing glitch is happening (usually because of concurrent VRAM writes while the rasterizer is at a that address)
- Debug splitscreen glitches