Grievous Bodily 'ARM screen geometry
Posted: Wed Nov 02, 2016 7:31 pm
None of the emulators get the geometry correct for this game. ADFFS' VIDC translation also gets it wrong.
I've compared the original, running on an ARM2/RO2 A310 vs Pi3 and the issue is probably the right border. When scrolling horizontally the left border width is changing, but the right border isn't; as a consequence the screen width is changing.
The game doesn't set HBSR/HBER. The only values set in-game are HDSR/HDER which are set to the scroll position + 1C / EC respectively, resulting in a screen width of 398 pixels. The scroll position values go from 0 to 3, so the game is sliding the visible window between 0 and 6 pixels in 2 pixel increments.
I've compared the original, running on an ARM2/RO2 A310 vs Pi3 and the issue is probably the right border. When scrolling horizontally the left border width is changing, but the right border isn't; as a consequence the screen width is changing.
The game doesn't set HBSR/HBER. The only values set in-game are HDSR/HDER which are set to the scroll position + 1C / EC respectively, resulting in a screen width of 398 pixels. The scroll position values go from 0 to 3, so the game is sliding the visible window between 0 and 6 pixels in 2 pixel increments.