- struct gl_texture_object *texObj = _mesa_get_fallback_texture(ctx);
- texUnit->_ReallyEnabled = 1 << TEXTURE_2D_INDEX;
+ struct gl_texture_object *texObj;
+ gl_texture_index texTarget;
+
+ assert(_mesa_bitcount(enabledTargets) == 1);
+
+ texTarget = (gl_texture_index) (ffs(enabledTargets) - 1);
+ texObj = _mesa_get_fallback_texture(ctx, texTarget);
+
+ assert(texObj);
+ if (!texObj) {
+ /* invalid fallback texture: don't enable the texture unit */
+ continue;
+ }
+