Enter The Realm screen geometry
Posted: Thu Feb 17, 2022 9:29 am
This game sets VBSR, VBER, HBSR and HBER, relying HDSR, HDER, VDSR, VDER to be "known" values.
Under the ADFFS blitter, the screen ends up with the wrong horizontal borders resulting in 4 pixels missing off the left of the screen and an additional 12 pixels on the right of the screen.
The screen width in pixels is correct at 304 pixels, its just the border positions that appear to be wrong.
Values written by the game are:
VBSR = 166-(1024>>3) = 38
VBER = 166+(1024>>3) = 294
HBSR = 143-(613>>3)+3 = 70
HBER = 143+(613>>3)+3 = 222
Which result in a screen width of 304 pixels, a left border overlap of 12 pixels and a right border overlap of 4 pixels using RISC OS 3.11 MODE 9 values.
For the game to appear correct, the left and right border overlaps need to be 8 pixels.
Under the ADFFS blitter, the screen ends up with the wrong horizontal borders resulting in 4 pixels missing off the left of the screen and an additional 12 pixels on the right of the screen.
The screen width in pixels is correct at 304 pixels, its just the border positions that appear to be wrong.
Values written by the game are:
VBSR = 166-(1024>>3) = 38
VBER = 166+(1024>>3) = 294
HBSR = 143-(613>>3)+3 = 70
HBER = 143+(613>>3)+3 = 222
Which result in a screen width of 304 pixels, a left border overlap of 12 pixels and a right border overlap of 4 pixels using RISC OS 3.11 MODE 9 values.
For the game to appear correct, the left and right border overlaps need to be 8 pixels.