Add a debug draw mode for displaying UV2 (lightmap) texel density

doc/classes/RenderingServer.xml

@@ -1809,6 +1809,14 @@
 				Sets the lightmap GI instance to use for the specified 3D geometry instance. The lightmap UV scale for the specified instance (equivalent to [member GeometryInstance3D.gi_lightmap_scale]) and lightmap atlas slice must also be specified.
 			</description>
 		</method>
+		<method name="instance_geometry_set_lightmap_scale">
+			<return type="void" />
+			<param index="0" name="instance" type="RID" />
+			<param index="1" name="lightmap_scale" type="float" />
+			<description>
+				Sets the lightmap scale for the given geometry instance.
+			</description>
+		</method>
 		<method name="instance_geometry_set_lod_bias">
 			<return type="void" />
 			<param index="0" name="instance" type="RID" />
@@ -2373,6 +2381,14 @@
 				Sets a mesh's custom aabb.
 			</description>
 		</method>
+		<method name="mesh_set_lightmap_size_hint">
+			<return type="void" />
+			<param index="0" name="mesh" type="RID" />
+			<param index="1" name="size" type="Vector2" />
+			<description>
+				Sets a mesh's lightmap size hint.
+			</description>
+		</method>
 		<method name="mesh_set_shadow_mesh">
 			<return type="void" />
 			<param index="0" name="mesh" type="RID" />
@@ -5003,24 +5019,27 @@
 		<constant name="VIEWPORT_DEBUG_DRAW_VOXEL_GI_EMISSION" value="8" enum="ViewportDebugDraw">
 			Objects are displayed with only the emission color from [VoxelGI]s.
 		</constant>
-		<constant name="VIEWPORT_DEBUG_DRAW_SHADOW_ATLAS" value="9" enum="ViewportDebugDraw">
+		<constant name="VIEWPORT_DEBUG_DRAW_UV2_TEXEL_DENSITY" value="9" enum="ViewportDebugDraw">
+			Objects are displayed with a checkerboard pattern indicative of their UV2 texel density. Each square of the checkerboard pattern is 10 texels by 10 texels in size.
+		</constant>
+		<constant name="VIEWPORT_DEBUG_DRAW_SHADOW_ATLAS" value="10" enum="ViewportDebugDraw">
 			Draws the shadow atlas that stores shadows from [OmniLight3D]s and [SpotLight3D]s in the upper left quadrant of the [Viewport].
 		</constant>
-		<constant name="VIEWPORT_DEBUG_DRAW_DIRECTIONAL_SHADOW_ATLAS" value="10" enum="ViewportDebugDraw">
+		<constant name="VIEWPORT_DEBUG_DRAW_DIRECTIONAL_SHADOW_ATLAS" value="11" enum="ViewportDebugDraw">
 			Draws the shadow atlas that stores shadows from [DirectionalLight3D]s in the upper left quadrant of the [Viewport].
 			The slice of the camera frustum related to the shadow map cascade is superimposed to visualize coverage. The color of each slice matches the colors used for [constant VIEWPORT_DEBUG_DRAW_PSSM_SPLITS]. When shadow cascades are blended the overlap is taken into account when drawing the frustum slices.
 			The last cascade shows all frustum slices to illustrate the coverage of all slices.
 		</constant>
 		<constant name="VIEWPORT_DEBUG_DRAW_SCENE_LUMINANCE" value="11" enum="ViewportDebugDraw">
 			Draws the estimated scene luminance. This is a 1×1 texture that is generated when autoexposure is enabled to control the scene's exposure.
 		</constant>
-		<constant name="VIEWPORT_DEBUG_DRAW_SSAO" value="12" enum="ViewportDebugDraw">
+		<constant name="VIEWPORT_DEBUG_DRAW_SSAO" value="13" enum="ViewportDebugDraw">
 			Draws the screen space ambient occlusion texture instead of the scene so that you can clearly see how it is affecting objects. In order for this display mode to work, you must have [member Environment.ssao_enabled] set in your [WorldEnvironment].
 		</constant>
-		<constant name="VIEWPORT_DEBUG_DRAW_SSIL" value="13" enum="ViewportDebugDraw">
+		<constant name="VIEWPORT_DEBUG_DRAW_SSIL" value="14" enum="ViewportDebugDraw">
 			Draws the screen space indirect lighting texture instead of the scene so that you can clearly see how it is affecting objects. In order for this display mode to work, you must have [member Environment.ssil_enabled] set in your [WorldEnvironment].
 		</constant>
-		<constant name="VIEWPORT_DEBUG_DRAW_PSSM_SPLITS" value="14" enum="ViewportDebugDraw">
+		<constant name="VIEWPORT_DEBUG_DRAW_PSSM_SPLITS" value="15" enum="ViewportDebugDraw">
 			Colors each PSSM split for the [DirectionalLight3D]s in the scene a different color so you can see where the splits are. In order they will be colored red, green, blue, yellow.
 		</constant>
 		<constant name="VIEWPORT_DEBUG_DRAW_DECAL_ATLAS" value="15" enum="ViewportDebugDraw">

doc/classes/Viewport.xml

@@ -551,25 +551,28 @@
 		<constant name="DEBUG_DRAW_VOXEL_GI_EMISSION" value="8" enum="DebugDraw">
 			Objects are displayed with only the emission color from [VoxelGI]s.
 		</constant>
-		<constant name="DEBUG_DRAW_SHADOW_ATLAS" value="9" enum="DebugDraw">
+		<constant name="DEBUG_DRAW_UV2_TEXEL_DENSITY" value="9" enum="DebugDraw">
+			Objects are displayed with a checkerboard pattern indicative of their UV2 texel density. Each square of the checkerboard pattern is 10 texels by 10 texels in size.
+		</constant>
+		<constant name="DEBUG_DRAW_SHADOW_ATLAS" value="10" enum="DebugDraw">
 			Draws the shadow atlas that stores shadows from [OmniLight3D]s and [SpotLight3D]s in the upper left quadrant of the [Viewport].
 		</constant>
-		<constant name="DEBUG_DRAW_DIRECTIONAL_SHADOW_ATLAS" value="10" enum="DebugDraw">
+		<constant name="DEBUG_DRAW_DIRECTIONAL_SHADOW_ATLAS" value="11" enum="DebugDraw">
 			Draws the shadow atlas that stores shadows from [DirectionalLight3D]s in the upper left quadrant of the [Viewport].
 		</constant>
 		<constant name="DEBUG_DRAW_SCENE_LUMINANCE" value="11" enum="DebugDraw">
 			Draws the scene luminance buffer (if available) in the upper left quadrant of the [Viewport].
 		</constant>
-		<constant name="DEBUG_DRAW_SSAO" value="12" enum="DebugDraw">
+		<constant name="DEBUG_DRAW_SSAO" value="13" enum="DebugDraw">
 			Draws the screen-space ambient occlusion texture instead of the scene so that you can clearly see how it is affecting objects. In order for this display mode to work, you must have [member Environment.ssao_enabled] set in your [WorldEnvironment].
 		</constant>
-		<constant name="DEBUG_DRAW_SSIL" value="13" enum="DebugDraw">
+		<constant name="DEBUG_DRAW_SSIL" value="14" enum="DebugDraw">
 			Draws the screen-space indirect lighting texture instead of the scene so that you can clearly see how it is affecting objects. In order for this display mode to work, you must have [member Environment.ssil_enabled] set in your [WorldEnvironment].
 		</constant>
-		<constant name="DEBUG_DRAW_PSSM_SPLITS" value="14" enum="DebugDraw">
+		<constant name="DEBUG_DRAW_PSSM_SPLITS" value="15" enum="DebugDraw">
 			Colors each PSSM split for the [DirectionalLight3D]s in the scene a different color so you can see where the splits are. In order, they will be colored red, green, blue, and yellow.
 		</constant>
-		<constant name="DEBUG_DRAW_DECAL_ATLAS" value="15" enum="DebugDraw">
+		<constant name="DEBUG_DRAW_DECAL_ATLAS" value="16" enum="DebugDraw">
 			Draws the decal atlas used by [Decal]s and light projector textures in the upper left quadrant of the [Viewport].
 		</constant>
 		<constant name="DEBUG_DRAW_SDFGI" value="16" enum="DebugDraw">

drivers/gles3/rasterizer_scene_gles3.cpp

@@ -1357,6 +1357,33 @@
 					}
 				}
 			}
+
+#ifdef DEBUG_ENABLED
+			if (unlikely(get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_UV2_TEXEL_DENSITY)) {
+				if (inst->data->base_type == RS::INSTANCE_MESH && inst->data->use_baked_light && inst->lightmap_instance.is_valid()) {
+					GLES3::LightStorage *light_storage = GLES3::LightStorage::get_singleton();
+
+					RID lightmap = light_storage->lightmap_instance_get_lightmap(inst->lightmap_instance);
+					Vector2i lightmap_atlas_size = light_storage->lightmap_get_light_texture_size(lightmap);
+
+					Size2 lightmap_size = inst->lightmap_uv_scale.size * Size2(lightmap_atlas_size);
+
+					if (inst->data->lightmap_size_global_uniform_pos == -2) {
+						// Not allocated, try to allocate.
+						inst->data->lightmap_size_global_uniform_pos = RSG::material_storage->global_shader_parameters_unit_variable_allocate();
+					}
+
+					if (inst->data->lightmap_size_global_uniform_pos >= 0) {
+						RSG::material_storage->global_shader_parameters_unit_variable_update(inst->data->lightmap_size_global_uniform_pos, lightmap_size);
+					}
+				}
+			} else if (unlikely(inst->data->lightmap_size_global_uniform_pos != -2)) {
+				if (inst->data->lightmap_size_global_uniform_pos >= 0) {
+					RSG::material_storage->global_shader_parameters_unit_variable_free(inst->data->lightmap_size_global_uniform_pos);
+				}
+				inst->data->lightmap_size_global_uniform_pos = -2;
+			}
+#endif
 		}
 
 		inst->flags_cache = flags;
@@ -2959,6 +2986,9 @@
 			} else if (unlikely(get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_LIGHTING)) {
 				material_data = default_material_data_ptr;
 				shader = material_data->shader_data;
+			} else if (unlikely(get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_UV2_TEXEL_DENSITY)) {
+				material_data = uv2_texel_density_material_data_ptr;
+				shader = material_data->shader_data;
 			} else {
 				shader = surf->shader;
 				material_data = surf->material;
@@ -3453,6 +3483,13 @@
 			}
 
 			material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::MODEL_FLAGS, inst->flags_cache, shader->version, instance_variant, spec_constants);
+			material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::INSTANCE_OFFSET, uint32_t(inst->shader_uniforms_offset), shader->version, instance_variant, spec_constants);
+
+#ifdef DEBUG_ENABLED
+			if (unlikely(get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_UV2_TEXEL_DENSITY && inst->data->use_baked_light && inst->data->lightmap_size_global_uniform_pos >= 0)) {
+				material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::INSTANCE_OFFSET, uint32_t(inst->data->lightmap_size_global_uniform_pos), shader->version, instance_variant, spec_constants);
+			}
+#endif
 
 			if (p_pass_mode == PASS_MODE_MATERIAL) {
 				material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::UV_OFFSET, p_params->uv_offset, shader->version, instance_variant, spec_constants);
@@ -4187,6 +4224,43 @@
 		overdraw_material_data_ptr = static_cast<GLES3::SceneMaterialData *>(GLES3::MaterialStorage::get_singleton()->material_get_data(scene_globals.overdraw_material, RS::SHADER_SPATIAL));
 	}
 
+	{
+		// UV2 debug shader.
+		scene_globals.uv2_texel_density_material_shader = material_storage->shader_allocate();
+		material_storage->shader_initialize(scene_globals.uv2_texel_density_material_shader);
+		material_storage->shader_set_code(scene_globals.uv2_texel_density_material_shader, R"(
+// 3D editor UV2 texel density debug draw mode shader (clustered).
+
+shader_type spatial;
+
+instance uniform vec2 lightmap_size : instance_index(0);
+
+void fragment() {
+	vec2 lightmap_pos = UV2 * lightmap_size;
+
+	vec2 ddx = dFdx(UV2);
+	vec2 ddy = dFdy(UV2);
+
+	vec2 w = max(abs(ddx), abs(ddy)) + 0.01;
+
+	vec2 s = 2.0 * (abs(fract((lightmap_pos - 0.5 * w) / 2.0) - 0.5) - abs(fract((lightmap_pos + 0.5 * w) / 2.0) - 0.5)) / w;
+
+	// Do a larger scale checkerboard as well.
+	lightmap_pos /= 10.0;
+	vec2 s2 = 2.0 * (abs(fract((lightmap_pos - 0.5 * w) / 2.0) - 0.5) - abs(fract((lightmap_pos + 0.5 * w) / 2.0) - 0.5)) / w;
+
+	float checkerboard_pattern = mix(0.85, 1.15, 0.5 - 0.5 * s2.x * s2.y);
+	checkerboard_pattern = checkerboard_pattern - mix(0.25, 0.5, 0.5 - 0.5 * s.x * s.y * sign(s2.x * s2.y)) ;
+
+	ALBEDO *= checkerboard_pattern;
+}
+)");
+		scene_globals.uv2_texel_density_material = material_storage->material_allocate();
+		material_storage->material_initialize(scene_globals.uv2_texel_density_material);
+		material_storage->material_set_shader(scene_globals.uv2_texel_density_material, scene_globals.uv2_texel_density_material_shader);
+		uv2_texel_density_material_data_ptr = static_cast<GLES3::SceneMaterialData *>(GLES3::MaterialStorage::get_singleton()->material_get_data(scene_globals.uv2_texel_density_material, RS::SHADER_SPATIAL));
+	}
+
 	{
 		// Initialize Sky stuff
 		sky_globals.roughness_layers = GLOBAL_GET("rendering/reflections/sky_reflections/roughness_layers");
@@ -4294,6 +4368,11 @@
 	RSG::material_storage->material_free(scene_globals.overdraw_material);
 	RSG::material_storage->shader_free(scene_globals.overdraw_shader);
 
+	// UV2 Debug Shader.
+	// Overdraw Shader
+	RSG::material_storage->material_free(scene_globals.uv2_texel_density_material);
+	RSG::material_storage->shader_free(scene_globals.uv2_texel_density_material_shader);
+
 	// Sky Shader
 	GLES3::MaterialStorage::get_singleton()->shaders.sky_shader.version_free(sky_globals.shader_default_version);
 	RSG::material_storage->material_free(sky_globals.default_material);

drivers/gles3/rasterizer_scene_gles3.h

@@ -166,10 +166,13 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 		RID default_shader;
 		RID overdraw_material;
 		RID overdraw_shader;
+		RID uv2_texel_density_material_shader;
+		RID uv2_texel_density_material;
 	} scene_globals;
 
 	GLES3::SceneMaterialData *default_material_data_ptr = nullptr;
 	GLES3::SceneMaterialData *overdraw_material_data_ptr = nullptr;
+	GLES3::SceneMaterialData *uv2_texel_density_material_data_ptr = nullptr;
 
 	/* LIGHT INSTANCE */
 

drivers/gles3/shaders/scene.glsl

@@ -261,6 +261,7 @@ uniform highp mat4 world_transform;
 uniform highp vec3 compressed_aabb_position;
 uniform highp vec3 compressed_aabb_size;
 uniform highp vec4 uv_scale;
+uniform highp uint instance_offset;
 
 uniform highp uint model_flags;
 
@@ -965,6 +966,7 @@ ivec2 multiview_uv(ivec2 uv) {
 uniform highp mat4 world_transform;
 uniform mediump float opaque_prepass_threshold;
 uniform highp uint model_flags;
+uniform highp uint instance_offset;
 
 #if defined(RENDER_MATERIAL)
 layout(location = 0) out vec4 albedo_output_buffer;

drivers/gles3/storage/light_storage.h

@@ -734,6 +734,11 @@ class LightStorage : public RendererLightStorage {
 	virtual void lightmap_set_probe_capture_update_speed(float p_speed) override;
 	virtual float lightmap_get_probe_capture_update_speed() const override;
 
+	_FORCE_INLINE_ Vector2i lightmap_get_light_texture_size(RID p_lightmap) const {
+		const Lightmap *lm = lightmap_owner.get_or_null(p_lightmap);
+		return lm->light_texture_size;
+	}
+
 	/* LIGHTMAP INSTANCE */
 
 	LightmapInstance *get_lightmap_instance(RID p_rid) { return lightmap_instance_owner.get_or_null(p_rid); };
@@ -743,6 +748,11 @@ class LightStorage : public RendererLightStorage {
 	virtual void lightmap_instance_free(RID p_lightmap) override;
 	virtual void lightmap_instance_set_transform(RID p_lightmap, const Transform3D &p_transform) override;
 
+	_FORCE_INLINE_ RID lightmap_instance_get_lightmap(RID p_lightmap_instance) {
+		LightmapInstance *li = lightmap_instance_owner.get_or_null(p_lightmap_instance);
+		return li->lightmap;
+	}
+
 	/* SHADOW ATLAS API */
 	bool owns_shadow_atlas(RID p_rid) { return shadow_atlas_owner.owns(p_rid); };
 

drivers/gles3/storage/material_storage.cpp

@@ -1371,6 +1371,7 @@ MaterialStorage::MaterialStorage() {
 
 		actions.check_multiview_samplers = RasterizerGLES3::get_singleton()->is_xr_enabled();
 		actions.global_buffer_array_variable = "global_shader_uniforms";
+		actions.instance_uniform_index_variable = "instance_offset";
 
 		shaders.compiler_scene.initialize(actions);
 	}
@@ -1993,6 +1994,57 @@ GLuint MaterialStorage::global_shader_parameters_get_uniform_buffer() const {
 	return global_shader_uniforms.buffer;
 }
 
+//An alternative way of allocating global shader uniforms.
+//Allocates a single variable and returns its position in the global shader uniform buffer.
+//Intended to be used for debug drawing purposes and should not be used for anything substantial.
+int32_t MaterialStorage::global_shader_parameters_unit_variable_allocate() {
+	int32_t pos = _global_shader_uniform_allocate(1);
+	ERR_FAIL_COND_V_MSG(pos < 0, -1, "Too many instances using shader instance variables. Increase buffer size in Project Settings.");
+	global_shader_uniforms.buffer_usage[pos].elements = 1;
+	return pos;
+}
+
+void MaterialStorage::global_shader_parameters_unit_variable_free(int32_t p_pos) {
+	ERR_FAIL_COND(p_pos < 0);
+	global_shader_uniforms.buffer_usage[p_pos].elements = 0;
+}
+
+void MaterialStorage::global_shader_parameters_unit_variable_update(int32_t p_pos, const Variant &p_value) {
+	ERR_FAIL_COND(p_pos < 0);
+	ERR_FAIL_COND_MSG(p_value.get_type() > Variant::COLOR, "Unsupported variant type."); //anything greater not supported
+
+	const ShaderLanguage::DataType datatype_from_value[Variant::COLOR + 1] = {
+		ShaderLanguage::TYPE_MAX, //nil
+		ShaderLanguage::TYPE_BOOL, //bool
+		ShaderLanguage::TYPE_INT, //int
+		ShaderLanguage::TYPE_FLOAT, //float
+		ShaderLanguage::TYPE_MAX, //string
+		ShaderLanguage::TYPE_VEC2, //vec2
+		ShaderLanguage::TYPE_IVEC2, //vec2i
+		ShaderLanguage::TYPE_VEC4, //rect2
+		ShaderLanguage::TYPE_IVEC4, //rect2i
+		ShaderLanguage::TYPE_VEC3, // vec3
+		ShaderLanguage::TYPE_IVEC3, //vec3i
+		ShaderLanguage::TYPE_MAX, //xform2d not supported here
+		ShaderLanguage::TYPE_VEC4, //vec4
+		ShaderLanguage::TYPE_IVEC4, //vec4i
+		ShaderLanguage::TYPE_VEC4, //plane
+		ShaderLanguage::TYPE_VEC4, //quat
+		ShaderLanguage::TYPE_MAX, //aabb not supported here
+		ShaderLanguage::TYPE_MAX, //basis not supported here
+		ShaderLanguage::TYPE_MAX, //xform not supported here
+		ShaderLanguage::TYPE_MAX, //projection not supported here
+		ShaderLanguage::TYPE_VEC4 //color
+	};
+
+	ShaderLanguage::DataType datatype = datatype_from_value[p_value.get_type()];
+
+	ERR_FAIL_COND_MSG(datatype == ShaderLanguage::TYPE_MAX, "Unsupported variant type.");
+
+	_fill_std140_variant_ubo_value(datatype, 0, p_value, (uint8_t *)&global_shader_uniforms.buffer_values[p_pos]);
+	_global_shader_uniform_mark_buffer_dirty(p_pos, 1);
+}
+
 int32_t MaterialStorage::global_shader_parameters_instance_allocate(RID p_instance) {
 	ERR_FAIL_COND_V(global_shader_uniforms.instance_buffer_pos.has(p_instance), -1);
 	int32_t pos = _global_shader_uniform_allocate(ShaderLanguage::MAX_INSTANCE_UNIFORM_INDICES);

drivers/gles3/storage/material_storage.h

@@ -568,6 +568,10 @@ class MaterialStorage : public RendererMaterialStorage {
 	virtual void global_shader_parameters_load_settings(bool p_load_textures = true) override;
 	virtual void global_shader_parameters_clear() override;
 
+	virtual int32_t global_shader_parameters_unit_variable_allocate() override;
+	virtual void global_shader_parameters_unit_variable_free(int32_t p_pos) override;
+	virtual void global_shader_parameters_unit_variable_update(int32_t p_pos, const Variant &p_value) override;
+
 	virtual int32_t global_shader_parameters_instance_allocate(RID p_instance) override;
 	virtual void global_shader_parameters_instance_free(RID p_instance) override;
 	virtual void global_shader_parameters_instance_update(RID p_instance, int p_index, const Variant &p_value, int p_flags_count = 0) override;

drivers/gles3/storage/mesh_storage.h

@@ -315,6 +315,7 @@ class MeshStorage : public RendererMeshStorage {
 	virtual String mesh_get_path(RID p_mesh) const override;
 
 	virtual void mesh_set_shadow_mesh(RID p_mesh, RID p_shadow_mesh) override;
+
 	virtual void mesh_clear(RID p_mesh) override;
 
 	_FORCE_INLINE_ const RID *mesh_get_surface_count_and_materials(RID p_mesh, uint32_t &r_surface_count) {