sprite rendering

Discuss emulation of the Nintendo Entertainment System and Famicom.

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sprite rendering

Post by mattmatteh? » Mon Aug 29, 2005 7:49 am

i am working on gettting sprites to work. reading BT docs, the sprite buffer is parsed during the rendering to fill the in range temp buffer. for accuracy, can this be done after the rendering but before hblank? or if the game does a mid scan trick i am not sure if i need to code that by ppu cc. i was going to code it by ppu cc during hblank for getting the in range sprites ready for the next scan line. sorry if i didnt word this question right.

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Post by Disch » Mon Aug 29, 2005 10:14 am

I loaded all the sprite data on cycle 256 of the previous scanline. That's probably "good enough" for every existing commercial game (I don't know of any which do mid-frame sprite tricks -- and if they do, they likely shut the PPU off for a few scanlines anyway)

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Post by Zepper » Mon Aug 29, 2005 3:41 pm

I can't say I'm right 'cuz my PPU engine starts at cc zero (instead of previous scanline bleh bleh). Anyway, by parsing the sprites during cc 0-255 would cause glitches due to $2002.20 being set prematurely (?). Taking cc 256 seems to fix this problem. It would require a real test though.


Post by Guest » Mon Aug 29, 2005 4:22 pm

what about the sprite computing during hblank? anyone have problems doing that at the end instead of by each ppu cc


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