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Bitmap rotation

Started by warm0ng3r Jul 31, 2001 at 10:38 AM 0 replies 600+ views

Original Post

Jul 31, 2001 at 10:38 AM

Tried rotating a bitmap in dd, and it didnt work..... checked the caps of my device (gf2 mx), and found it doesnt have this capability..... Checked in Sisoft Sandra, and yes, it confirmed - the gf2 mx doesnt have hardware bitmap rotation (and dx doesnt have a HEL version) - now I thought this was pretty strange for such a mainstream card.... where can i get an algorithm to emulate bitmap rotation? here in castle camelot we eat ham and jam and spam alot!

PyroBoy

Jul 31, 2001 at 1:23 PM

I don''t know of any video cards offhand that acually have hardware DD blit rotation. It''s extremely uncommon, and there doesn''t seem to be any hurry to implement it in successive generations of hardware since graphics technology is focusing on 3D so much (DX8 not having Blt anymore certainly re-enforces this trend). Same goes for alpha blended blts too.

The solution is to use Direct3D or OpenGL to render 2D polygons with textures on them. They look just like regular sprites(better, actually, due to the 3D card''s texture filtering), and can easily be rotated, scaled and whatnot. You can also add hardware alpha blending support very easily.

There are a lot of tutorials on "3D-for-2D" out there, and I''d definately reccommend this method for all your 2D needs.

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