vbo: Only mark merged line strips as lines when actually converting them

We only convert line strips to lines in certain cases, but were flagging
node->merged.prim as GL_LINES even if we simply copied a GL_LINE_STRIP
prim[0] over without modifying it.

Fixes Piglit's lineloop test (which triggers loop -> strip conversion
earlier in this path, then was incorrectly triggering strip -> list
mode modification with no changes to the underlying data).

Fixes: 310991415ee ("vbo/dlist: implement primitive merging")
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8522>

diff --git a/src/mesa/vbo/vbo_save_api.c b/src/mesa/vbo/vbo_save_api.c
index b258e6a..b5d7d67 100644 (file)
--- a/src/mesa/vbo/vbo_save_api.c
+++ b/src/mesa/vbo/vbo_save_api.c
@@ -688,7 +688,7 @@ compile_vertex_list(struct gl_context *ctx)
             continue;
          }
 
-         /* Line strips get converted to lines */
+         /* Line strips may get converted to lines */
          if (mode == GL_LINE_STRIP)
             mode = GL_LINES;
 
@@ -739,6 +739,9 @@ compile_vertex_list(struct gl_context *ctx)
                }
             }
          } else {
+            /* We didn't convert to LINES, so restore the original mode */
+            mode = original_prims[i].mode;
+
             for (unsigned j = 0; j < vertex_count; j++) {
                indices[idx++] = original_prims[i].start + j;
             }