English Amiga Board - View Single Post - Compileable version of Alien Breed 3D II

pipper · 11 August 2022, 02:55

I understand the issue now, just need a proper fix.
The mouse look has the ability to move the center of the rendering "MIDDLEY" up and down pixel by pixel.
A globale variable "SBIGMIDDLEY" is pointing to the middle of the screen as a byte offset (basically MIDDLEY * 320). Now the mouse can move that center up and down even to odd lines.
The other code in double height floor drawing assumed that the center of the screen is aligned to an even line and offsets its drawing accordingly.
But if it already starts at and odd line, all lines produced will end up on odd lines. And these will be skipped from C2P and do not show up on the screen.

11 August 2022, 02:55	#121
pipper Registered User Join Date: Jul 2017 Location: San Jose Posts: 652	I understand the issue now, just need a proper fix. The mouse look has the ability to move the center of the rendering "MIDDLEY" up and down pixel by pixel. A globale variable "SBIGMIDDLEY" is pointing to the middle of the screen as a byte offset (basically MIDDLEY * 320). Now the mouse can move that center up and down even to odd lines. The other code in double height floor drawing assumed that the center of the screen is aligned to an even line and offsets its drawing accordingly. But if it already starts at and odd line, all lines produced will end up on odd lines. And these will be skipped from C2P and do not show up on the screen.