Fix T91838 Crash when toggling edit mode on object with geometry node modifier, but only if the instanced objects material has a normal map assigned.

This is only a workaround to avoid the crash. The underlying issue is left
unfixed.

New report for tracking the underlying issue is T93223.

1 files changed, 8 insertions, 1 deletions

diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_tan.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_tan.cc
index 1f8776fc98e..7a3b2cf49ff 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_tan.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_tan.cc
@@ -54,11 +54,18 @@ static void extract_tan_ex_init(const MeshRenderData *mr,
   uint32_t tan_layers = cache->cd_used.tan;
   float(*orco)[3] = (float(*)[3])CustomData_get_layer(cd_vdata, CD_ORCO);
   bool orco_allocated = false;
-  const bool use_orco_tan = cache->cd_used.tan_orco != 0;
+  bool use_orco_tan = cache->cd_used.tan_orco != 0;
 
   int tan_len = 0;
   char tangent_names[MAX_MTFACE][MAX_CUSTOMDATA_LAYER_NAME];
 
+  /* FIXME(T91838): This is to avoid a crash when orco tangent was requested but there are valid
+   * uv layers. It would be better to fix the root cause. */
+  if (tan_layers == 0 && use_orco_tan && CustomData_get_layer_index(cd_ldata, CD_MLOOPUV) != -1) {
+    tan_layers = 1;
+    use_orco_tan = false;
+  }
+
   for (int i = 0; i < MAX_MTFACE; i++) {
     if (tan_layers & (1 << i)) {
       char attr_name[32], attr_safe_name[GPU_MAX_SAFE_ATTR_NAME];