draw: fix incorrect color of flat-shaded clipped lines

When we clipped a line weren't copying the provoking vertex
color to the second vertex.  We also weren't checking for
first vs. last provoking vertex.

Fixes failures found with the new piglit line-flat-clip-color test.

Cc: "10.0, 10.1" <[email protected]>

Reviewed-by: Jose Fonseca <[email protected]>

1 files changed, 12 insertions, 1 deletions

diff --git a/src/gallium/auxiliary/draw/draw_pipe_clip.c b/src/gallium/auxiliary/draw/draw_pipe_clip.c
index de354e9e9da..d8b56de4d2f 100644
--- a/src/gallium/auxiliary/draw/draw_pipe_clip.c
+++ b/src/gallium/auxiliary/draw/draw_pipe_clip.c
@@ -588,7 +588,12 @@ do_clip_line( struct draw_stage *stage,
 
    if (v0->clipmask) {
       interp( clipper, stage->tmp[0], t0, v0, v1, viewport_index );
-      copy_flat(stage, stage->tmp[0], v0);
+      if (stage->draw->rasterizer->flatshade_first) {
+         copy_flat(stage, stage->tmp[0], v0);  /* copy v0 color to tmp[0] */
+      }
+      else {
+         copy_flat(stage, stage->tmp[0], v1);  /* copy v1 color to tmp[0] */
+      }
       newprim.v[0] = stage->tmp[0];
    }
    else {
@@ -597,6 +602,12 @@ do_clip_line( struct draw_stage *stage,
 
    if (v1->clipmask) {
       interp( clipper, stage->tmp[1], t1, v1, v0, viewport_index );
+      if (stage->draw->rasterizer->flatshade_first) {
+         copy_flat(stage, stage->tmp[1], v0);  /* copy v0 color to tmp[1] */
+      }
+      else {
+         copy_flat(stage, stage->tmp[1], v1);  /* copy v1 color to tmp[1] */
+      }
       newprim.v[1] = stage->tmp[1];
    }
    else {