xiaoshuxing wrote: > Hello. Everybody: > > I’ve been reading the source code of mesa recently, and what puzzles me > a lot is that I can’t find the function to fetch pixels from the color > buffer when rendering to the screen. > > I’ve set several breakpoints in the file > “s_span.c(_swrast_read_rgba_span,_swrast_get_values, _swrast_get_row)” > ,“wmesa.c(read_rgba_pixels(/spans)_32)”, which I thought have the most > possibility to be the right one, but none of them was hit when I was > running in the debug mode in Visual studio.net 2005. > > So is there anybody who can give me a clue that which function may be > invoked when the application reads pixels from framebuffer and render it > to the screen. > > any help will be appreciated.
One of several different paths may be taken to implement glReadPixels: 1. The driver might plug in a hardware-specific ReadPixels routine into ctx->Driver.ReadPixels(). I don't think the Windows driver does that. 2. The swrast module can try an optimized routine, like fast_read_rgba_pixels() (in s_readpix.c) for simple cases. 3. If neither of those is used, the swrast module will basically use _swrast_read_rgba_span() to read pixels a row at a time, before applying the pixel transfer operations. If you stop your debugger in _mesa_ReadPixels() it should be easy to trace the path. -Brian ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
