GP2X Hardware Dithering ?


rixed

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Finally I got some polygons rendered in the Gp2x.
I wanted to enable hardware dithering (register 2946h) but apparently it's not working.

Did someone managed to enable this in 16bpp mode ?

I (lamely) rely on this feature to smooth my textures :)
 
rixed posted on May 3 2006 at 12:36 AM said:
Finally I got some polygons rendered in the Gp2x.
I wanted to enable hardware dithering (register 2946h) but apparently it's not working.

Did someone managed to enable this in 16bpp mode ?

I (lamely) rely on this feature to smooth my textures :)
From looking at the docs, it appears that dithering is only applied if the source format has a greater resolution than the destination. If you're in 16-bit colour mode, I doubt if you will see it, as you would have to be rendering from 24-bit sources to have dithering applied, and you might not even notice it if it was there. I could be mistaken, of course.
 
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scorpio posted on May 3 2006 at 02:25 AM said:
From looking at the docs, it appears that dithering is only applied if the source format has a greater resolution than the destination.

I dont quite understand this. When using RGB layer, how is it possible to have different source and destination format ??
 
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rixed posted on May 3 2006 at 02:02 AM said:
scorpio posted on May 3 2006 at 02:25 AM said:
From looking at the docs, it appears that dithering is only applied if the source format has a greater resolution than the destination.

I dont quite understand this. When using RGB layer, how is it possible to have different source and destination format ??
You've got me there. I was hoping you wouldn't ask that until I'd had a chance to look into it a bit more!

I initially though it was to do with rendering the YUV data, but the docs suggest that it is applicable to the RGB layer. I have a feeling it might just be poor wording in the docs, and that it's actually a dither which is applied to the YUV video layers as they are rendered into the current display mode, and has nothing to do with the RGB layers at all.
 
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Isn't it like with playing movies; You filter down from 24-bit to 16-bit source.

And since the 2D accelerator is made for 16-bit redering and video playing.

Anyway, this is odd, because when viewing a dark scene in a movie, I've never noticed dithering, just layers of different shades of black.
 
rixed posted on May 3 2006 at 02:02 AM said:
scorpio posted on May 3 2006 at 02:25 AM said:
From looking at the docs, it appears that dithering is only applied if the source format has a greater resolution than the destination.

I dont quite understand this. When using RGB layer, how is it possible to have different source and destination format ??
The RGB layer can be set to 24-bit, and 8-bit uses 24-bit colours. The display is run at 18-bit (6-6-6) to the LCD, and 24-bit to TV-Out. It may be that it only applies to the YUV layers, I keep meaning to check but I'm as forgetful as an ... erm... one of those :)
 
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