Merge pull request #86583 from reduz/lightmapper-dda-fix

Tiny fix for lightmapper DDA

2 files changed, 11 insertions, 2 deletions

diff --git a/editor/plugins/lightmap_gi_editor_plugin.cpp b/editor/plugins/lightmap_gi_editor_plugin.cpp
index 3b1b1e47cb..335498dff9 100644
--- a/editor/plugins/lightmap_gi_editor_plugin.cpp
+++ b/editor/plugins/lightmap_gi_editor_plugin.cpp
@@ -105,7 +105,7 @@ void LightmapGIEditorPlugin::_bake_select_file(const String &p_file) {
 				EditorNode::get_singleton()->show_warning(TTR("Lightmap data is not local to the scene."));
 			} break;
 			case LightmapGI::BAKE_ERROR_TEXTURE_SIZE_TOO_SMALL: {
-				EditorNode::get_singleton()->show_warning(TTR("Maximum texture size is too small for the lightmap images."));
+				EditorNode::get_singleton()->show_warning(TTR("Maximum texture size is too small for the lightmap images.\nWhile this can be fixed by increasing the maximum texture size, it is recommended you split the scene into more objects instead."));
 			} break;
 			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."));
diff --git a/modules/lightmapper_rd/lm_compute.glsl b/modules/lightmapper_rd/lm_compute.glsl
index a2a480043a..21e039396d 100644
--- a/modules/lightmapper_rd/lm_compute.glsl
+++ b/modules/lightmapper_rd/lm_compute.glsl
@@ -264,7 +264,16 @@ uint trace_ray(vec3 p_from, vec3 p_to, bool p_any_hit, out float r_distance, out
 			break;
 		}
 
-		bvec3 mask = lessThanEqual(side.xyz, min(side.yzx, side.zxy));
+		// There should be only one axis updated at a time for DDA to work properly.
+		bvec3 mask = bvec3(true, false, false);
+		float m = side.x;
+		if (side.y < m) {
+			m = side.y;
+			mask = bvec3(false, true, false);
+		}
+		if (side.z < m) {
+			mask = bvec3(false, false, true);
+		}
 		side += vec3(mask) * delta;
 		icell += ivec3(vec3(mask)) * step;
 		iters++;