Implement support for bicubic lightmap filtering

Co-authored-by: Calinou <hugo.locurcio@hugo.pro>

doc/classes/LightmapGIData.xml

@@ -15,8 +15,9 @@
 			<param index="1" name="uv_scale" type="Rect2" />
 			<param index="2" name="slice_index" type="int" />
 			<param index="3" name="sub_instance" type="int" />
+			<param index="4" name="texture_size" type="Vector2" />
 			<description>
-				Adds an object that is considered baked within this [LightmapGIData].
+				Adds an object that is considered baked within this [LightmapGIData]. [param texture_size] must match the size of the [i]entire[/i] lightmap texture, which is used for bicubic filtering when rendering the lightmap.
 			</description>
 		</method>
 		<method name="clear_users">

drivers/gles3/rasterizer_scene_gles3.cpp

@@ -129,10 +129,11 @@ void RasterizerSceneGLES3::GeometryInstanceGLES3::_mark_dirty() {
 	RasterizerSceneGLES3::get_singleton()->geometry_instance_dirty_list.add(&dirty_list_element);
 }
 
-void RasterizerSceneGLES3::GeometryInstanceGLES3::set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index) {
+void RasterizerSceneGLES3::GeometryInstanceGLES3::set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index, const Vector2 &p_lightmap_texture_size) {
 	lightmap_instance = p_lightmap_instance;
 	lightmap_uv_scale = p_lightmap_uv_scale;
 	lightmap_slice_index = p_lightmap_slice_index;
+	lightmap_texture_size = p_lightmap_texture_size;
 
 	_mark_dirty();
 }
@@ -3343,6 +3344,8 @@ void RasterizerSceneGLES3::_render_list_template(RenderListParameters *p_params,
 						Vector4 uv_scale(inst->lightmap_uv_scale.position.x, inst->lightmap_uv_scale.position.y, inst->lightmap_uv_scale.size.x, inst->lightmap_uv_scale.size.y);
 						material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::LIGHTMAP_UV_SCALE, uv_scale, shader->version, instance_variant, spec_constants);
 
+						material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::LIGHTMAP_TEXTURE_SIZE, inst->lightmap_texture_size, shader->version, instance_variant, spec_constants);
+
 						float exposure_normalization = 1.0;
 						if (p_render_data->camera_attributes.is_valid()) {
 							float enf = RSG::camera_attributes->camera_attributes_get_exposure_normalization_factor(p_render_data->camera_attributes);

drivers/gles3/rasterizer_scene_gles3.h

@@ -317,6 +317,7 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 		RID lightmap_instance;
 		Rect2 lightmap_uv_scale;
 		uint32_t lightmap_slice_index;
+		Vector2 lightmap_texture_size;
 		GeometryInstanceLightmapSH *lightmap_sh = nullptr;
 
 		// Used during setup.
@@ -327,7 +328,7 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 				dirty_list_element(this) {}
 
 		virtual void _mark_dirty() override;
-		virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index) override;
+		virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index, const Vector2 &p_lightmap_texture_size) override;
 		virtual void set_lightmap_capture(const Color *p_sh9) override;
 
 		virtual void pair_light_instances(const RID *p_light_instances, uint32_t p_light_instance_count) override;

drivers/gles3/shaders/scene.glsl

@@ -880,6 +880,11 @@ uniform lowp uint lightmap_slice;
 uniform highp vec4 lightmap_uv_scale;
 uniform float lightmap_exposure_normalization;
 
+#define LIGHTMAP_BICUBIC_FILTER // FIXME: Remove this and pass when compiling shader.
+#ifdef LIGHTMAP_BICUBIC_FILTER
+uniform highp vec2 lightmap_texture_size;
+#endif
+
 #ifdef USE_SH_LIGHTMAP
 uniform mediump mat3 lightmap_normal_xform;
 #endif // USE_SH_LIGHTMAP
@@ -1287,6 +1292,69 @@ vec4 fog_process(vec3 vertex) {
 
 #endif // !MODE_RENDER_DEPTH
 
+#ifdef LIGHTMAP_BICUBIC_FILTER
+
+// w0, w1, w2, and w3 are the four cubic B-spline basis functions
+float w0(float a) {
+	return (1.0 / 6.0) * (a * (a * (-a + 3.0) - 3.0) + 1.0);
+}
+
+float w1(float a) {
+	return (1.0 / 6.0) * (a * a * (3.0 * a - 6.0) + 4.0);
+}
+
+float w2(float a) {
+	return (1.0 / 6.0) * (a * (a * (-3.0 * a + 3.0) + 3.0) + 1.0);
+}
+
+float w3(float a) {
+	return (1.0 / 6.0) * (a * a * a);
+}
+
+// g0 and g1 are the two amplitude functions
+float g0(float a) {
+	return w0(a) + w1(a);
+}
+
+float g1(float a) {
+	return w2(a) + w3(a);
+}
+
+// h0 and h1 are the two offset functions
+float h0(float a) {
+	return -1.0 + w1(a) / (w0(a) + w1(a));
+}
+
+float h1(float a) {
+	return 1.0 + w3(a) / (w2(a) + w3(a));
+}
+
+vec4 textureArray_bicubic(sampler2DArray tex, vec3 uv, vec2 texture_size) {
+	vec2 texel_size = vec2(1.0) / texture_size;
+
+	uv.xy = uv.xy * texture_size + vec2(0.5);
+
+	vec2 iuv = floor(uv.xy);
+	vec2 fuv = fract(uv.xy);
+
+	float g0x = g0(fuv.x);
+	float g1x = g1(fuv.x);
+	float h0x = h0(fuv.x);
+	float h1x = h1(fuv.x);
+	float h0y = h0(fuv.y);
+	float h1y = h1(fuv.y);
+
+	vec2 p0 = (vec2(iuv.x + h0x, iuv.y + h0y) - vec2(0.5)) * texel_size;
+	vec2 p1 = (vec2(iuv.x + h1x, iuv.y + h0y) - vec2(0.5)) * texel_size;
+	vec2 p2 = (vec2(iuv.x + h0x, iuv.y + h1y) - vec2(0.5)) * texel_size;
+	vec2 p3 = (vec2(iuv.x + h1x, iuv.y + h1y) - vec2(0.5)) * texel_size;
+
+	return (g0(fuv.y) * (g0x * texture(tex, vec3(p0, uv.z)) + g1x * texture(tex, vec3(p1, uv.z)))) +
+			(g1(fuv.y) * (g0x * texture(tex, vec3(p2, uv.z)) + g1x * texture(tex, vec3(p3, uv.z))));
+}
+
+#endif // LIGHTMAP_BICUBIC_FILTER
+
 void main() {
 	//lay out everything, whatever is unused is optimized away anyway
 	vec3 vertex = vertex_interp;
@@ -1542,10 +1610,18 @@ void main() {
 
 #ifdef USE_SH_LIGHTMAP
 		uvw.z *= 4.0; // SH textures use 4 times more data.
+
+#ifdef LIGHTMAP_BICUBIC_FILTER
+		vec3 lm_light_l0 = textureArray_bicubic(lightmap_textures, uvw + vec3(0.0, 0.0, 0.0), lightmap_texture_size);
+		vec3 lm_light_l1n1 = textureArray_bicubic(lightmap_textures, uvw + vec3(0.0, 0.0, 1.0), lightmap_texture_size);
+		vec3 lm_light_l1_0 = textureArray_bicubic(lightmap_textures, uvw + vec3(0.0, 0.0, 2.0), lightmap_texture_size);
+		vec3 lm_light_l1p1 = textureArray_bicubic(lightmap_textures, uvw + vec3(0.0, 0.0, 3.0), lightmap_texture_size);
+#else
 		vec3 lm_light_l0 = textureLod(lightmap_textures, uvw + vec3(0.0, 0.0, 0.0), 0.0).rgb;
 		vec3 lm_light_l1n1 = textureLod(lightmap_textures, uvw + vec3(0.0, 0.0, 1.0), 0.0).rgb;
 		vec3 lm_light_l1_0 = textureLod(lightmap_textures, uvw + vec3(0.0, 0.0, 2.0), 0.0).rgb;
 		vec3 lm_light_l1p1 = textureLod(lightmap_textures, uvw + vec3(0.0, 0.0, 3.0), 0.0).rgb;
+#endif
 
 		vec3 n = normalize(lightmap_normal_xform * normal);
 
@@ -1559,8 +1635,12 @@ void main() {
 			specular_light += lm_light_l1_0 * 0.32573 * r.z * lightmap_exposure_normalization;
 			specular_light += lm_light_l1p1 * 0.32573 * r.x * lightmap_exposure_normalization;
 		}
+#else
+#ifdef LIGHTMAP_BICUBIC_FILTER
+		ambient_light += textureArray_bicubic(lightmap_textures, uvw, lightmap_texture_size).rgb * lightmap_exposure_normalization;
 #else
 		ambient_light += textureLod(lightmap_textures, uvw, 0.0).rgb * lightmap_exposure_normalization;
+#endif
 #endif
 	}
 #endif // USE_LIGHTMAP

scene/3d/lightmap_gi.cpp

@@ -40,12 +40,13 @@
 #include "scene/resources/image_texture.h"
 #include "scene/resources/sky.h"
 
-void LightmapGIData::add_user(const NodePath &p_path, const Rect2 &p_uv_scale, int p_slice_index, int32_t p_sub_instance) {
+void LightmapGIData::add_user(const NodePath &p_path, const Rect2 &p_uv_scale, int p_slice_index, int32_t p_sub_instance, const Vector2 &p_texture_size) {
 	User user;
 	user.path = p_path;
 	user.uv_scale = p_uv_scale;
 	user.slice_index = p_slice_index;
 	user.sub_instance = p_sub_instance;
+	user.texture_size = p_texture_size;
 	users.push_back(user);
 }
 
@@ -73,16 +74,21 @@ int LightmapGIData::get_user_lightmap_slice_index(int p_user) const {
 	return users[p_user].slice_index;
 }
 
+Vector2 LightmapGIData::get_user_lightmap_texture_size(int p_user) const {
+	ERR_FAIL_INDEX_V(p_user, users.size(), Vector2());
+	return users[p_user].texture_size;
+}
+
 void LightmapGIData::clear_users() {
 	users.clear();
 }
 
 void LightmapGIData::_set_user_data(const Array &p_data) {
 	ERR_FAIL_COND(p_data.is_empty());
-	ERR_FAIL_COND((p_data.size() % 4) != 0);
+	ERR_FAIL_COND((p_data.size() % 5) != 0);
 
-	for (int i = 0; i < p_data.size(); i += 4) {
-		add_user(p_data[i + 0], p_data[i + 1], p_data[i + 2], p_data[i + 3]);
+	for (int i = 0; i < p_data.size(); i += 5) {
+		add_user(p_data[i + 0], p_data[i + 1], p_data[i + 2], p_data[i + 3], p_data[i + 4]);
 	}
 }
 
@@ -93,6 +99,7 @@ Array LightmapGIData::_get_user_data() const {
 		ret.push_back(users[i].uv_scale);
 		ret.push_back(users[i].slice_index);
 		ret.push_back(users[i].sub_instance);
+		ret.push_back(users[i].texture_size);
 	}
 	return ret;
 }
@@ -1155,7 +1162,8 @@ LightmapGI::BakeError LightmapGI::bake(Node *p_from_node, String p_image_data_pa
 
 		Rect2 uv_scale = lightmapper->get_bake_mesh_uv_scale(i);
 		int slice_index = lightmapper->get_bake_mesh_texture_slice(i);
-		gi_data->add_user(np, uv_scale, slice_index, subindex);
+		Ref<Image> lightmap = lightmapper->get_bake_texture(slice_index);
+		gi_data->add_user(np, uv_scale, slice_index, subindex, Vector2(lightmap->get_width(), lightmap->get_height()));
 	}
 
 	{
@@ -1329,12 +1337,12 @@ void LightmapGI::_assign_lightmaps() {
 		if (instance_idx >= 0) {
 			RID instance_id = node->call("get_bake_mesh_instance", instance_idx);
 			if (instance_id.is_valid()) {
-				RS::get_singleton()->instance_geometry_set_lightmap(instance_id, get_instance(), light_data->get_user_lightmap_uv_scale(i), light_data->get_user_lightmap_slice_index(i));
+				RS::get_singleton()->instance_geometry_set_lightmap(instance_id, get_instance(), light_data->get_user_lightmap_uv_scale(i), light_data->get_user_lightmap_slice_index(i), light_data->get_user_lightmap_texture_size(i));
 			}
 		} else {
 			VisualInstance3D *vi = Object::cast_to<VisualInstance3D>(node);
 			ERR_CONTINUE(!vi);
-			RS::get_singleton()->instance_geometry_set_lightmap(vi->get_instance(), get_instance(), light_data->get_user_lightmap_uv_scale(i), light_data->get_user_lightmap_slice_index(i));
+			RS::get_singleton()->instance_geometry_set_lightmap(vi->get_instance(), get_instance(), light_data->get_user_lightmap_uv_scale(i), light_data->get_user_lightmap_slice_index(i), light_data->get_user_lightmap_texture_size(i));
 		}
 	}
 }
@@ -1347,12 +1355,12 @@ void LightmapGI::_clear_lightmaps() {
 		if (instance_idx >= 0) {
 			RID instance_id = node->call("get_bake_mesh_instance", instance_idx);
 			if (instance_id.is_valid()) {
-				RS::get_singleton()->instance_geometry_set_lightmap(instance_id, RID(), Rect2(), 0);
+				RS::get_singleton()->instance_geometry_set_lightmap(instance_id, RID(), Rect2(), 0, Vector2());
 			}
 		} else {
 			VisualInstance3D *vi = Object::cast_to<VisualInstance3D>(node);
 			ERR_CONTINUE(!vi);
-			RS::get_singleton()->instance_geometry_set_lightmap(vi->get_instance(), RID(), Rect2(), 0);
+			RS::get_singleton()->instance_geometry_set_lightmap(vi->get_instance(), RID(), Rect2(), 0, Vector2());
 		}
 	}
 }

scene/3d/lightmap_gi.h

@@ -57,6 +57,7 @@ class LightmapGIData : public Resource {
 		NodePath path;
 		int32_t sub_instance = 0;
 		Rect2 uv_scale;
+		Vector2 texture_size;
 		int slice_index = 0;
 	};
 
@@ -73,12 +74,13 @@ class LightmapGIData : public Resource {
 	static void _bind_methods();
 
 public:
-	void add_user(const NodePath &p_path, const Rect2 &p_uv_scale, int p_slice_index, int32_t p_sub_instance = -1);
+	void add_user(const NodePath &p_path, const Rect2 &p_uv_scale, int p_slice_index, int32_t p_sub_instance = -1, const Vector2 &p_texture_size = Vector2());
 	int get_user_count() const;
 	NodePath get_user_path(int p_user) const;
 	int32_t get_user_sub_instance(int p_user) const;
 	Rect2 get_user_lightmap_uv_scale(int p_user) const;
 	int get_user_lightmap_slice_index(int p_user) const;
+	Vector2 get_user_lightmap_texture_size(int p_user) const;
 	void clear_users();
 
 #ifndef DISABLE_DEPRECATED

servers/rendering/dummy/rasterizer_scene_dummy.h

@@ -57,7 +57,7 @@ class RasterizerSceneDummy : public RendererSceneRender {
 		virtual void set_transparency(float p_transparency) override {}
 		virtual void set_use_baked_light(bool p_enable) override {}
 		virtual void set_use_dynamic_gi(bool p_enable) override {}
-		virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index) override {}
+		virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index, const Vector2 &p_lightmap_texture_size) override {}
 		virtual void set_lightmap_capture(const Color *p_sh9) override {}
 		virtual void set_instance_shader_uniforms_offset(int32_t p_offset) override {}
 		virtual void set_cast_double_sided_shadows(bool p_enable) override {}

servers/rendering/renderer_geometry_instance.h

@@ -58,7 +58,7 @@ class RenderGeometryInstance {
 	virtual void set_transparency(float p_transparency) = 0;
 	virtual void set_use_baked_light(bool p_enable) = 0;
 	virtual void set_use_dynamic_gi(bool p_enable) = 0;
-	virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index) = 0;
+	virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index, const Vector2 &p_lightmap_texture_size) = 0;
 	virtual void set_lightmap_capture(const Color *p_sh9) = 0;
 	virtual void set_instance_shader_uniforms_offset(int32_t p_offset) = 0;
 	virtual void set_cast_double_sided_shadows(bool p_enable) = 0;

servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.cpp

@@ -731,6 +731,8 @@ void RenderForwardClustered::_fill_instance_data(RenderListType p_render_list, i
 		instance_data.lightmap_uv_scale[1] = inst->lightmap_uv_scale.position.y;
 		instance_data.lightmap_uv_scale[2] = inst->lightmap_uv_scale.size.x;
 		instance_data.lightmap_uv_scale[3] = inst->lightmap_uv_scale.size.y;
+		instance_data.lightmap_texture_size[0] = inst->lightmap_texture_size.x;
+		instance_data.lightmap_texture_size[1] = inst->lightmap_texture_size.y;
 
 		AABB surface_aabb = AABB(Vector3(0.0, 0.0, 0.0), Vector3(1.0, 1.0, 1.0));
 		uint64_t format = RendererRD::MeshStorage::get_singleton()->mesh_surface_get_format(surface->surface);
@@ -4107,9 +4109,10 @@ void RenderForwardClustered::GeometryInstanceForwardClustered::set_transform(con
 	RenderGeometryInstanceBase::set_transform(p_transform, p_aabb, p_transformed_aabb);
 }
 
-void RenderForwardClustered::GeometryInstanceForwardClustered::set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index) {
+void RenderForwardClustered::GeometryInstanceForwardClustered::set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index, const Vector2 &p_lightmap_texture_size) {
 	lightmap_instance = p_lightmap_instance;
 	lightmap_uv_scale = p_lightmap_uv_scale;
+	lightmap_texture_size = p_lightmap_texture_size;
 	lightmap_slice_index = p_lightmap_slice_index;
 
 	_mark_dirty();

servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.h

@@ -309,6 +309,8 @@ class RenderForwardClustered : public RendererSceneRenderRD {
 			float compressed_aabb_position[4];
 			float compressed_aabb_size[4];
 			float uv_scale[4];
+			float lightmap_texture_size[2];
+			uint32_t padding[2];
 		};
 
 		UBO ubo;
@@ -456,6 +458,7 @@ class RenderForwardClustered : public RendererSceneRenderRD {
 		// lightmap
 		RID lightmap_instance;
 		Rect2 lightmap_uv_scale;
+		Vector2 lightmap_texture_size; // Used for bicubic filtering in the scene shader.
 		uint32_t lightmap_slice_index;
 		GeometryInstanceLightmapSH *lightmap_sh = nullptr;
 
@@ -484,7 +487,7 @@ class RenderForwardClustered : public RendererSceneRenderRD {
 		virtual void _mark_dirty() override;
 
 		virtual void set_transform(const Transform3D &p_transform, const AABB &p_aabb, const AABB &p_transformed_aabb) override;
-		virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index) override;
+		virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index, const Vector2 &p_lightmap_texture_size) override;
 		virtual void set_lightmap_capture(const Color *p_sh9) override;
 
 		virtual void pair_light_instances(const RID *p_light_instances, uint32_t p_light_instance_count) override {}

servers/rendering/renderer_rd/forward_mobile/render_forward_mobile.cpp

@@ -1733,6 +1733,8 @@ void RenderForwardMobile::_fill_instance_data(RenderListType p_render_list, uint
 		instance_data.lightmap_uv_scale[1] = inst->lightmap_uv_scale.position.y;
 		instance_data.lightmap_uv_scale[2] = inst->lightmap_uv_scale.size.x;
 		instance_data.lightmap_uv_scale[3] = inst->lightmap_uv_scale.size.y;
+		instance_data.lightmap_texture_size[0] = inst->lightmap_texture_size.x;
+		instance_data.lightmap_texture_size[1] = inst->lightmap_texture_size.y;
 
 		AABB surface_aabb = AABB(Vector3(0.0, 0.0, 0.0), Vector3(1.0, 1.0, 1.0));
 		uint64_t format = RendererRD::MeshStorage::get_singleton()->mesh_surface_get_format(surface->surface);
@@ -2254,9 +2256,10 @@ RenderGeometryInstance *RenderForwardMobile::geometry_instance_create(RID p_base
 	return ginstance;
 }
 
-void RenderForwardMobile::GeometryInstanceForwardMobile::set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index) {
+void RenderForwardMobile::GeometryInstanceForwardMobile::set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index, const Vector2 &p_lightmap_texture_size) {
 	lightmap_instance = p_lightmap_instance;
 	lightmap_uv_scale = p_lightmap_uv_scale;
+	lightmap_texture_size = p_lightmap_texture_size;
 	lightmap_slice_index = p_lightmap_slice_index;
 
 	_mark_dirty();

servers/rendering/renderer_rd/forward_mobile/render_forward_mobile.h

@@ -240,6 +240,8 @@ class RenderForwardMobile : public RendererSceneRenderRD {
 			float compressed_aabb_position[4];
 			float compressed_aabb_size[4];
 			float uv_scale[4];
+			float lightmap_texture_size[2];
+			uint32_t padding[2];
 		};
 
 		RID instance_buffer[RENDER_LIST_MAX];
@@ -470,6 +472,7 @@ class RenderForwardMobile : public RendererSceneRenderRD {
 		uint32_t gi_offset_cache = 0; // !BAS! Should rename this to lightmap_offset_cache, in forward clustered this was shared between gi and lightmap
 		RID lightmap_instance;
 		Rect2 lightmap_uv_scale;
+		Vector2 lightmap_texture_size; // Used for bicubic filtering in the scene shader.
 		uint32_t lightmap_slice_index;
 		GeometryInstanceLightmapSH *lightmap_sh = nullptr;
 
@@ -493,7 +496,7 @@ class RenderForwardMobile : public RendererSceneRenderRD {
 
 		virtual void _mark_dirty() override;
 
-		virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index) override;
+		virtual void set_use_lightmap(RID p_lightmap_instance, const Rect2 &p_lightmap_uv_scale, int p_lightmap_slice_index, const Vector2 &p_lightmap_texture_size) override;
 		virtual void set_lightmap_capture(const Color *p_sh9) override;
 
 		virtual void pair_light_instances(const RID *p_light_instances, uint32_t p_light_instance_count) override;