When, during the rendering of a scanline, are sprite patterns fetched? Can anyone make this clear?
I'm trying to reload sprite patterns through CHR bankswitching, and I want this to be a clean switch: one scanline uses the previous patterns, and the very next one uses the new patters, but I notice that a few sprites in this split area (it probably depends on the order they were evaluated) have a line that flickers between the 2 sets of patterns.
Currently, I'm waiting for the visible start of the scanline to do the switch (because I assumed the patterns were fetched during the previous HBlank, after the sprites were evaluated), but that must be wrong. Please tell me if there is a safe time to switch the sprite patterns.
Thanks for the help.
EDIT: 2C02 technical reference.TXT says that this happens during "Memory fetch phase 129 thru 160", but I'm not sure what those numbers mean (they are not clock cycles!), so I can't tell when exactly is this... little help? I'll keep reading the doc anyway, maybe I'll find something.
I'm trying to reload sprite patterns through CHR bankswitching, and I want this to be a clean switch: one scanline uses the previous patterns, and the very next one uses the new patters, but I notice that a few sprites in this split area (it probably depends on the order they were evaluated) have a line that flickers between the 2 sets of patterns.
Currently, I'm waiting for the visible start of the scanline to do the switch (because I assumed the patterns were fetched during the previous HBlank, after the sprites were evaluated), but that must be wrong. Please tell me if there is a safe time to switch the sprite patterns.
Thanks for the help.
EDIT: 2C02 technical reference.TXT says that this happens during "Memory fetch phase 129 thru 160", but I'm not sure what those numbers mean (they are not clock cycles!), so I can't tell when exactly is this... little help? I'll keep reading the doc anyway, maybe I'll find something.