These are all useful code snippets that show how to do different tasks in 9900 assembler.
Pixel perfect sprite to background coincidence checking..... Same method and code used in Mad Marvin's Great Escape !!
The following file is a routine that allows a programmer to make sprite to background graphics coincidence checks on a pixel basis. I works by providing a 16 x 16 pixel sprite definition that mirrors the exact space in the graphics plane that is under the player sprite. The inputs are the X and Y location of the player sprite, The output is a 32 byte pattern definition that can be directly loaded into the Sprite Pattern Descriptor Table. If another sprite is laid on top of the player sprite, it's color made transparent and is defined by the routine output then the VDP will detect the collision for the programmer while the player will not see the extra sprite. This file is in TI99-PC disk image format.
| s2bcoince.dsk |