message: Fix build with new textureparam struct
diff: @@ -162,7 +162,7 @@ vec4f DRR_shadeSurface(const DistributedRaycastRenderer *uniform self,
  foreach_unique (m in mat) {
  surfaceColor = m->Kd;
  opacity = m->d;
  - if (m->map_Kd) {
  + if (valid(m->map_Kd)) {
  vec4f kdFromMap = get4f(m->map_Kd, dg);
  surfaceColor = surfaceColor * make_vec3f(kdFromMap);
  }
  