From: Roland Scheidegger <sroland@vmware.com>
Date: Tue, 24 Apr 2018 16:12:34 +0000 (+0200)
Subject: draw: simplify clip null tri logic
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=98578df27bbf682f254d59a3a7d63b5f1b98f838;p=mesa.git

draw: simplify clip null tri logic

Simplifies the logic when to emit null tris (albeit the reasons why we
have to do this remain unclear).
This is strictly just logic simplification, the behavior doesn't change
at all.

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
---

diff --git a/src/gallium/auxiliary/draw/draw_pipe_clip.c b/src/gallium/auxiliary/draw/draw_pipe_clip.c
index 4cfa54b2e17..ff80363a51e 100644
--- a/src/gallium/auxiliary/draw/draw_pipe_clip.c
+++ b/src/gallium/auxiliary/draw/draw_pipe_clip.c
@@ -252,8 +252,7 @@ static void emit_poly(struct draw_stage *stage,
    struct prim_header header;
    unsigned i;
    ushort edge_first, edge_middle, edge_last;
-   boolean last_tri_was_null = FALSE;
-   boolean tri_was_not_null = FALSE;
+   boolean tri_emitted = FALSE;
 
    if (stage->draw->rasterizer->flatshade_first) {
       edge_first  = DRAW_PIPE_EDGE_FLAG_0;
@@ -289,17 +288,16 @@ static void emit_poly(struct draw_stage *stage,
       }
 
       tri_null = is_tri_null(clipper, &header);
-      /* If we generated a triangle with an area, aka. non-null triangle,
-       * or if the previous triangle was also null then skip all subsequent
-       * null triangles */
-      if ((tri_was_not_null && tri_null) || (last_tri_was_null && tri_null)) {
-         last_tri_was_null = tri_null;
+      /*
+       * If we ever generated a tri (regardless if it had area or not),
+       * skip all subsequent null tris.
+       * FIXME: it is unclear why we always have to emit at least one
+       * tri. Maybe this is hiding bugs elsewhere.
+       */
+      if (tri_null && tri_emitted) {
          continue;
       }
-      last_tri_was_null = tri_null;
-      if (!tri_null) {
-         tri_was_not_null = TRUE;
-      }
+      tri_emitted = TRUE;
 
       if (!edgeflags[i-1]) {
          header.flags &= ~edge_middle;