Fix T77195: Crash with edit-mesh viewport measurements enabled

Simplify looping over faces & tessellation data.

Regression in 6526c3ced8b5, the index accessed wasn't valid.

1 files changed, 8 insertions, 4 deletions

diff --git a/source/blender/draw/intern/draw_manager_text.c b/source/blender/draw/intern/draw_manager_text.c
index 23956df71e8..f4601fe4f48 100644
--- a/source/blender/draw/intern/draw_manager_text.c
+++ b/source/blender/draw/intern/draw_manager_text.c
@@ -395,16 +395,19 @@ void DRW_text_edit_mesh_measure_stats(ARegion *region,
 
     UI_GetThemeColor3ubv(TH_DRAWEXTRA_FACEAREA, col);
 
-    int i, n, numtri;
+    int i, n;
     BMFace *f = NULL;
+    /* Alternative to using `poly_to_tri_count(i, BM_elem_index_get(f->l_first))`
+     * without having to add an extra loop. */
+    int looptri_index = 0;
     BM_ITER_MESH_INDEX (f, &iter, em->bm, BM_FACES_OF_MESH, i) {
+      const int f_looptri_len = f->len - 2;
       if (BM_elem_flag_test(f, BM_ELEM_SELECT)) {
         n = 0;
-        numtri = f->len - 2;
         area = 0;
         zero_v3(vmid);
-        BMLoop *(*l)[3] = &em->looptris[poly_to_tri_count(i, BM_elem_index_get(f->l_first))];
-        for (int j = 0; j < numtri; j++) {
+        BMLoop *(*l)[3] = &em->looptris[looptri_index];
+        for (int j = 0; j < f_looptri_len; j++) {
 
           if (use_coords) {
             copy_v3_v3(v1, vert_coords[BM_elem_index_get(l[j][0]->v)]);
@@ -449,6 +452,7 @@ void DRW_text_edit_mesh_measure_stats(ARegion *region,
 
         DRW_text_cache_add(dt, vmid, numstr, numstr_len, 0, 0, txt_flag, col);
       }
+      looptri_index += f_looptri_len;
     }
   }