Lightmapper: Prevent infinite loop when blitting lightmaps into an atlas

doc/classes/LightmapGI.xml

@@ -137,6 +137,12 @@
  <constant name="BAKE_ERROR_TEXTURE_SIZE_TOO_SMALL" value="9" enum="BakeError">
  Lightmap baking failed as the maximum texture size is too small to fit some of the meshes marked for baking.
  </constant>
+ <constant name="BAKE_ERROR_LIGHTMAP_TOO_SMALL" value="10" enum="BakeError">
+ Lightmap baking failed as the lightmap is too small.
+ </constant>
+ <constant name="BAKE_ERROR_ATLAS_TOO_SMALL" value="11" enum="BakeError">
+ Lightmap baking failed as the lightmap was unable to fit into an atlas.
+ </constant>
  <constant name="ENVIRONMENT_MODE_DISABLED" value="0" enum="EnvironmentMode">
  Ignore environment lighting when baking lightmaps.
  </constant>

editor/plugins/lightmap_gi_editor_plugin.cpp

@@ -110,6 +110,9 @@ void LightmapGIEditorPlugin::_bake_select_file(const String &p_file) {
  case LightmapGI::BAKE_ERROR_LIGHTMAP_TOO_SMALL: {
  EditorNode::get_singleton()->show_warning(TTR("Failed creating lightmap images. Make sure all meshes selected to bake have `lightmap_size_hint` value set high enough, and `texel_scale` value of LightmapGI is not too low."));
  } break;
+ case LightmapGI::BAKE_ERROR_ATLAS_TOO_SMALL: {
+ EditorNode::get_singleton()->show_warning(TTR("Failed fitting a lightmap image into an atlas. This should never happen and should be reported."));
+ } break;
  default: {
  } break;
  }

modules/lightmapper_rd/lightmapper_rd.cpp

@@ -240,7 +240,7 @@ Lightmapper::BakeError LightmapperRD::_blit_meshes_into_atlas(int p_max_texture_
  max = MAX(max, nearest_power_of_2_templated(atlas_size.height));
 
  if (max > p_max_texture_size) {
- return BAKE_ERROR_LIGHTMAP_TOO_SMALL;
+ return BAKE_ERROR_TEXTURE_EXCEEDS_MAX_SIZE;
  }
 
  if (p_step_function) {
@@ -254,19 +254,27 @@ Lightmapper::BakeError LightmapperRD::_blit_meshes_into_atlas(int p_max_texture_
  int best_atlas_memory = 0x7FFFFFFF;
  Vector<Vector3i> best_atlas_offsets;
 
- //determine best texture array atlas size by bruteforce fitting
+ // Determine best texture array atlas size by bruteforce fitting.
  while (atlas_size.x <= p_max_texture_size && atlas_size.y <= p_max_texture_size) {
  Vector<Vector2i> source_sizes;
  Vector<int> source_indices;
  source_sizes.resize(sizes.size());
  source_indices.resize(sizes.size());
  for (int i = 0; i < source_indices.size(); i++) {
- source_sizes.write[i] = sizes[i] + Vector2i(2, 2).maxi(p_denoiser_range); // Add padding between lightmaps
+ source_sizes.write[i] = sizes[i] + Vector2i(2, 2).maxi(p_denoiser_range); // Add padding between lightmaps.
  source_indices.write[i] = i;
  }
  Vector<Vector3i> atlas_offsets;
  atlas_offsets.resize(source_sizes.size());
 
+ // Ensure the sizes can all fit into a single atlas layer.
+ // This should always happen, and this check is only in place to prevent an infinite loop.
+ for (int i = 0; i < source_sizes.size(); i++) {
+ if (source_sizes[i] > atlas_size) {
+ return BAKE_ERROR_ATLAS_TOO_SMALL;
+ }
+ }
+
  int slices = 0;
 
  while (source_sizes.size() > 0) {

scene/3d/lightmap_gi.cpp

@@ -1104,10 +1104,12 @@ LightmapGI::BakeError LightmapGI::bake(Node *p_from_node, String p_image_data_pa
 
  Lightmapper::BakeError bake_err = lightmapper->bake(Lightmapper::BakeQuality(bake_quality), use_denoiser, denoiser_strength, denoiser_range, bounces, bounce_indirect_energy, bias, max_texture_size, directional, use_texture_for_bounces, Lightmapper::GenerateProbes(gen_probes), environment_image, environment_transform, _lightmap_bake_step_function, &bsud, exposure_normalization);
 
- if (bake_err == Lightmapper::BAKE_ERROR_LIGHTMAP_TOO_SMALL) {
+ if (bake_err == Lightmapper::BAKE_ERROR_TEXTURE_EXCEEDS_MAX_SIZE) {
  return BAKE_ERROR_TEXTURE_SIZE_TOO_SMALL;
  } else if (bake_err == Lightmapper::BAKE_ERROR_LIGHTMAP_CANT_PRE_BAKE_MESHES) {
  return BAKE_ERROR_MESHES_INVALID;
+ } else if (bake_err == Lightmapper::BAKE_ERROR_ATLAS_TOO_SMALL) {
+ return BAKE_ERROR_ATLAS_TOO_SMALL;
  }
 
  // POSTBAKE: Save Textures.
@@ -1711,6 +1713,8 @@ void LightmapGI::_bind_methods() {
  BIND_ENUM_CONSTANT(BAKE_ERROR_CANT_CREATE_IMAGE);
  BIND_ENUM_CONSTANT(BAKE_ERROR_USER_ABORTED);
  BIND_ENUM_CONSTANT(BAKE_ERROR_TEXTURE_SIZE_TOO_SMALL);
+ BIND_ENUM_CONSTANT(BAKE_ERROR_LIGHTMAP_TOO_SMALL);
+ BIND_ENUM_CONSTANT(BAKE_ERROR_ATLAS_TOO_SMALL);
 
  BIND_ENUM_CONSTANT(ENVIRONMENT_MODE_DISABLED);
  BIND_ENUM_CONSTANT(ENVIRONMENT_MODE_SCENE);

scene/3d/lightmap_gi.h

@@ -143,6 +143,7 @@ class LightmapGI : public VisualInstance3D {
  BAKE_ERROR_USER_ABORTED,
  BAKE_ERROR_TEXTURE_SIZE_TOO_SMALL,
  BAKE_ERROR_LIGHTMAP_TOO_SMALL,
+ BAKE_ERROR_ATLAS_TOO_SMALL,
  };
 
  enum EnvironmentMode {

scene/3d/lightmapper.h

@@ -143,9 +143,10 @@ class Lightmapper : public RefCounted {
  };
 
  enum BakeError {
- BAKE_ERROR_LIGHTMAP_TOO_SMALL,
+ BAKE_OK,
+ BAKE_ERROR_TEXTURE_EXCEEDS_MAX_SIZE,
  BAKE_ERROR_LIGHTMAP_CANT_PRE_BAKE_MESHES,
- BAKE_OK
+ BAKE_ERROR_ATLAS_TOO_SMALL,
  };
 
  enum BakeQuality {