Hi all, I have been working to add indexed drawing/glDrawElements support to the mesa-lima driver currently in development (https://github.com/yuq/mesa-lima). For that implementation, it seems that we need to have the minimum and maximum index values from the index buffer available in order to set up a proper command stream. Mesa provides these values in pipe_draw_info.min_index and pipe_draw_info.max_index, however in some cases we noticed that it decides to not calculate those. This happens because of st_context.draw_needs_minmax_index being false after evaluating the vertex data. In those cases, min_index gets to be 0 and max_index gets to be 0xffffffff. According to the gallium documentation, this seems to be on purpose and apparently drivers should be able to handle the 0 and 0xffffffff case and be able to render anyway. However, we haven't figured out a way to do the render anyway with 0 and 0xffffffff.
For us it would be interesting to always have mesa calculate those values for indexed drawing. We haven't been able to figure out a way to do that without changing the mesa generic code. Is there some way we could accomplish that in driver specific code? Otherwise, can you provide some advice on how to best handle this? Using mesa 17.3 and kmscube with the following patch is one way to reproduce st_context.draw_needs_minmax_index not being set. https://gist.githubusercontent.com/enunes/366398fbee3d194deb3a46ef9c2ca78d/raw/82a2c8084236e35635b7a247609213d0068974e3/kmscube.patch The only way that this works for us with the current implementation is by hacking st_context.draw_needs_minmax_index to be always true in some way. Thanks Erico _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
