Quoting Adam Agnew ([EMAIL PROTECTED]): > > I'm surprised to see how much a Pentium2 300Mhz MMX on a Matrox G550 > spanks my Voodoo3 3500 on a dual AMD 1800+ XP. This makes it quite obvious > that we're really depending heavily on hardware acceleration especially > for all things alpha channel :P So, two questions: > 1) Are there any speed ups for software based rendering that can be done > but have not yet been implemented? The project I'm working on depends > heavily on alpha channels so I'd be very interested in any software speed > ups we can get. and
The alpha channel blending stuff is slow because reading from video memory is 10 times slower than writing into it. Try df_dok --system. At least for video memory blending I see no real optimizing chances. For system memory a specialized software routine for one of over 100 different combinations of blend functions and blitting flags could give 10-20%. > 2) Are the alpha-channel hardware speed ups dependant on some kind of > hardware feature? I know some recent cards have made a big woopdie-doo > about anti-aliasing in games. Are these features DirectFB is tapping into? Anti Aliasing in hardware is not used to do alpha blending. Glyphs are rendered by freetype and blitted using alpha blending. AA in hardware would only make sense for lines and triangles. The performance of alpha blending in hardware simply depends on the graphics chip. On a Matrox card we are using the texture mapping unit, so the windows are textures ;) The Rage 128 has a 2D scaler that can do alpha blending. -- Best regards, Denis Oliver Kropp .------------------------------------------. | DirectFB - Hardware accelerated graphics | | http://www.directfb.org/ | "------------------------------------------" convergence integrated media GmbH -- Info: To unsubscribe send a mail to [EMAIL PROTECTED] with "unsubscribe directfb-dev" as subject.
