From: Roland Scheidegger Date: Fri, 11 Dec 2015 01:21:17 +0000 (+0100) Subject: draw: fix clipping with linear interpolated values and gl_ClipVertex X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=64c59b06244fc34f015f1f75b8205ac597ab0105;p=mesa.git draw: fix clipping with linear interpolated values and gl_ClipVertex Discovered this when working on other clip code, apparently didn't work correctly - the combination of linear interpolated values and using gl_ClipVertex produced wrong values (failing all such combinations in piglits glsl-1.30 interpolation tests, named interpolation-noperspective-XXX-vertex). Use the pre-clip-pos values when determining the interpolation factor to fix this. Noone really understands this code well, but everybody agrees this looks sane... This fixes all those failing tests (10 in total) both with the llvm and non-llvm draw paths, with no piglit regressions. Reviewed-by: Brian Paul Reviewed-by: Dave Airlie --- diff --git a/src/gallium/auxiliary/draw/draw_pipe_clip.c b/src/gallium/auxiliary/draw/draw_pipe_clip.c index 35e54f4a8be..47765cd0ef9 100644 --- a/src/gallium/auxiliary/draw/draw_pipe_clip.c +++ b/src/gallium/auxiliary/draw/draw_pipe_clip.c @@ -192,11 +192,11 @@ static void interp(const struct clip_stage *clip, t_nopersp = t; /* find either in.x != out.x or in.y != out.y */ for (k = 0; k < 2; k++) { - if (in->clip[k] != out->clip[k]) { + if (in->pre_clip_pos[k] != out->pre_clip_pos[k]) { /* do divide by W, then compute linear interpolation factor */ - float in_coord = in->clip[k] / in->clip[3]; - float out_coord = out->clip[k] / out->clip[3]; - float dst_coord = dst->clip[k] / dst->clip[3]; + float in_coord = in->pre_clip_pos[k] / in->pre_clip_pos[3]; + float out_coord = out->pre_clip_pos[k] / out->pre_clip_pos[3]; + float dst_coord = dst->pre_clip_pos[k] / dst->pre_clip_pos[3]; t_nopersp = (dst_coord - out_coord) / (in_coord - out_coord); break; }