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Bunnz

Alpha blend modes

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I''m the lucky owner of a 3dfx Voodoo 3 card! The Voodoo boards have the disadvantage, that they only like textures in 16 bit and not bigger than 256*256! For my 2D Game I want to include clouds and fog, .... My problem: clouds - alpha blending (4444 bit-mode) no 8888 on Voodoo!!!! That means that there are 16 different alpha values! For a white cloud, that looks not that nice, although I''ve played a lot around with dithering, ... Then I''ve played around with the blend modes: DEST_BLEND = ONE SOURCE_BLEND = INVSRCCOLOR tata!!!! now the Alpha value is taken from the color! (565 mode) => more shades => better looking picture!!! This works great - perhaps only on my card??? So but if i want to do this for other colors than white, the fog or cloud is never full opaque (because alpha is taken from color - color not 255/255/255 or (31/63/32) or whatever .... Now: Is there another blend mode? Works this blend mode on most cards??? Do you know another solution???? How do you handle textures bigger than 256*256 (bilinear filtering gap) .... So far so goo Thanks in advance Bunnz

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In Unreal Tournament, the character skins were 512x512. Because of the Voodoo''s limitation, they split the character''s skin into 4 256x256 bitmaps. You could do the same.

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Can there be a problem with texture splitting if Bilinear Filtering is on?
Cause I''ve heard that there will be a gap (cause is interpolates with black or another color)???

Bunnz

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You can get artifacts with texture splitting, especially with bilinear filtering on. What you need to do to get rid of these artifacts is to include one pixel border from the other parts. This would of course leave you with a maximum of 254*254 texture size. Texture splitting is a difficult task to do right.

I think you should use A8L8 textures for your clouds. That way you have 256 levels of alpha in addition to 256 levels of shading.

If you want more levels of alpha for colored textures you should be able to use multitexturing where you use an alpha texture in the second pass.

Besides, I thought the Voodoo 3 could handle 32 bit modes and textures!?!



- WitchLord

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Guest Anonymous Poster
Besides, I also thought the Voodoo 3 could handle 32 bit modes and textures before i bought it!?!

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