3 files changed, 30 insertions, 13 deletions
diff --git a/modules/lightmapper_rd/lm_common_inc.glsl b/modules/lightmapper_rd/lm_common_inc.glsl
index 22172d50e4..58523dc1f8 100644
--- a/modules/lightmapper_rd/lm_common_inc.glsl
+++ b/modules/lightmapper_rd/lm_common_inc.glsl
@@ -81,3 +81,7 @@ layout(set = 0, binding = 8) uniform texture2DArray albedo_tex;
 layout(set = 0, binding = 9) uniform texture2DArray emission_tex;
 
 layout(set = 0, binding = 10) uniform sampler linear_sampler;
+
+// Fragment action constants
+const uint FA_NONE = 0;
+const uint FA_SMOOTHEN_POSITION = 1;
diff --git a/modules/lightmapper_rd/lm_compute.glsl b/modules/lightmapper_rd/lm_compute.glsl
index 25b334c5eb..158cd960c4 100644
--- a/modules/lightmapper_rd/lm_compute.glsl
+++ b/modules/lightmapper_rd/lm_compute.glsl
@@ -94,13 +94,14 @@ params;
 
 //check it, but also return distance and barycentric coords (for uv lookup)
 bool ray_hits_triangle(vec3 from, vec3 dir, float max_dist, vec3 p0, vec3 p1, vec3 p2, out float r_distance, out vec3 r_barycentric) {
+	const float EPSILON = 0.00001;
 	const vec3 e0 = p1 - p0;
 	const vec3 e1 = p0 - p2;
 	vec3 triangle_normal = cross(e1, e0);
 
 	float n_dot_dir = dot(triangle_normal, dir);
 
-	if (abs(n_dot_dir) < 0.01) {
+	if (abs(n_dot_dir) < EPSILON) {
 		return false;
 	}
 
@@ -148,7 +149,7 @@ uint trace_ray(vec3 p_from, vec3 p_to
 	ivec3 icell = ivec3(from_cell);
 	ivec3 iendcell = ivec3(to_cell);
 	vec3 dir_cell = normalize(rel_cell);
-	vec3 delta = abs(1.0 / dir_cell); //vec3(length(rel_cell)) / rel_cell);
+	vec3 delta = min(abs(1.0 / dir_cell), params.grid_size); // use params.grid_size as max to prevent infinity values
 	ivec3 step = ivec3(sign(rel_cell));
 	vec3 side = (sign(rel_cell) * (vec3(icell) - from_cell) + (sign(rel_cell) * 0.5) + 0.5) * delta;
 
@@ -420,20 +421,22 @@ void main() {
 
 			light = textureLod(sampler2DArray(source_light, linear_sampler), uvw, 0.0).rgb;
 			active_rays += 1.0;
-		} else if (trace_result == RAY_MISS && params.env_transform[0][3] == 0.0) { // Use env_transform[0][3] to indicate when we are computing the first bounce
-			// Did not hit a triangle, reach out for the sky
-			vec3 sky_dir = normalize(mat3(params.env_transform) * ray_dir);
+		} else if (trace_result == RAY_MISS) {
+			if (params.env_transform[0][3] == 0.0) { // Use env_transform[0][3] to indicate when we are computing the first bounce
+				// Did not hit a triangle, reach out for the sky
+				vec3 sky_dir = normalize(mat3(params.env_transform) * ray_dir);
 
-			vec2 st = vec2(
-					atan(sky_dir.x, sky_dir.z),
-					acos(sky_dir.y));
+				vec2 st = vec2(
+						atan(sky_dir.x, sky_dir.z),
+						acos(sky_dir.y));
 
-			if (st.x < 0.0)
-				st.x += PI * 2.0;
+				if (st.x < 0.0)
+					st.x += PI * 2.0;
 
-			st /= vec2(PI * 2.0, PI);
+				st /= vec2(PI * 2.0, PI);
 
-			light = textureLod(sampler2D(environment, linear_sampler), st, 0.0).rgb;
+				light = textureLod(sampler2D(environment, linear_sampler), st, 0.0).rgb;
+			}
 			active_rays += 1.0;
 		}
 
diff --git a/modules/lightmapper_rd/lm_raster.glsl b/modules/lightmapper_rd/lm_raster.glsl
index 55ca193cc1..a86968a4f3 100644
--- a/modules/lightmapper_rd/lm_raster.glsl
+++ b/modules/lightmapper_rd/lm_raster.glsl
@@ -12,6 +12,7 @@ layout(location = 2) out vec2 uv_interp;
 layout(location = 3) out vec3 barycentric;
 layout(location = 4) flat out uvec3 vertex_indices;
 layout(location = 5) flat out vec3 face_normal;
+layout(location = 6) flat out uint fragment_action;
 
 layout(push_constant, binding = 0, std430) uniform Params {
 	vec2 atlas_size;
@@ -49,6 +50,14 @@ void main() {
 
 	face_normal = -normalize(cross((vertices.data[vertex_indices.x].position - vertices.data[vertex_indices.y].position), (vertices.data[vertex_indices.x].position - vertices.data[vertex_indices.z].position)));
 
+	{
+		const float FLAT_THRESHOLD = 0.99;
+		const vec3 norm_a = vec3(vertices.data[vertex_indices.x].normal_xy, vertices.data[vertex_indices.x].normal_z);
+		const vec3 norm_b = vec3(vertices.data[vertex_indices.y].normal_xy, vertices.data[vertex_indices.y].normal_z);
+		const vec3 norm_c = vec3(vertices.data[vertex_indices.z].normal_xy, vertices.data[vertex_indices.z].normal_z);
+		fragment_action = (dot(norm_a, norm_b) < FLAT_THRESHOLD || dot(norm_a, norm_c) < FLAT_THRESHOLD || dot(norm_b, norm_c) < FLAT_THRESHOLD) ? FA_SMOOTHEN_POSITION : FA_NONE;
+	}
+
 	gl_Position = vec4((uv_interp + params.uv_offset) * 2.0 - 1.0, 0.0001, 1.0);
 }
 
@@ -78,6 +87,7 @@ layout(location = 2) in vec2 uv_interp;
 layout(location = 3) in vec3 barycentric;
 layout(location = 4) in flat uvec3 vertex_indices;
 layout(location = 5) in flat vec3 face_normal;
+layout(location = 6) in flat uint fragment_action;
 
 layout(location = 0) out vec4 position;
 layout(location = 1) out vec4 normal;
@@ -86,7 +96,7 @@ layout(location = 2) out vec4 unocclude;
 void main() {
 	vec3 vertex_pos = vertex_interp;
 
-	{
+	if (fragment_action == FA_SMOOTHEN_POSITION) {
 		// smooth out vertex position by interpolating its projection in the 3 normal planes (normal plane is created by vertex pos and normal)
 		// because we don't want to interpolate inwards, normals found pointing inwards are pushed out.
 		vec3 pos_a = vertices.data[vertex_indices.x].position;