Implement 3D shadows in the GL Compatibility renderer

drivers/gles3/effects/copy_effects.cpp

@@ -134,6 +134,16 @@ void CopyEffects::copy_screen() {
 	draw_screen_triangle();
 }
 
+void CopyEffects::copy_cube_to_rect(const Rect2 &p_rect) {
+	bool success = copy.shader.version_bind_shader(copy.shader_version, CopyShaderGLES3::MODE_CUBE_TO_OCTAHEDRAL);
+	if (!success) {
+		return;
+	}
+
+	copy.shader.version_set_uniform(CopyShaderGLES3::COPY_SECTION, p_rect.position.x, p_rect.position.y, p_rect.size.x, p_rect.size.y, copy.shader_version, CopyShaderGLES3::MODE_COPY_SECTION);
+	draw_screen_quad();
+}
+
 // Intended for efficiently mipmapping textures.
 void CopyEffects::bilinear_blur(GLuint p_source_texture, int p_mipmap_count, const Rect2i &p_region) {
 	GLuint framebuffers[2];

drivers/gles3/effects/copy_effects.h

@@ -63,6 +63,7 @@ class CopyEffects {
 	// These functions assume that a framebuffer and texture are bound already. They only manage the shader, uniforms, and vertex array.
 	void copy_to_rect(const Rect2 &p_rect);
 	void copy_screen();
+	void copy_cube_to_rect(const Rect2 &p_rect);
 	void bilinear_blur(GLuint p_source_texture, int p_mipmap_count, const Rect2i &p_region);
 	void gaussian_blur(GLuint p_source_texture, int p_mipmap_count, const Rect2i &p_region, const Size2i &p_size);
 	void set_color(const Color &p_color, const Rect2i &p_region);

drivers/gles3/rasterizer_scene_gles3.h

@@ -59,7 +59,6 @@ enum RenderListType {
 enum PassMode {
 	PASS_MODE_COLOR,
 	PASS_MODE_COLOR_TRANSPARENT,
-	PASS_MODE_COLOR_ADDITIVE,
 	PASS_MODE_SHADOW,
 	PASS_MODE_DEPTH,
 };
@@ -75,6 +74,8 @@ enum SceneUniformLocation {
 	SCENE_SPOTLIGHT_UNIFORM_LOCATION,
 	SCENE_DIRECTIONAL_LIGHT_UNIFORM_LOCATION,
 	SCENE_MULTIVIEW_UNIFORM_LOCATION,
+	SCENE_POSITIONAL_SHADOW_UNIFORM_LOCATION,
+	SCENE_DIRECTIONAL_SHADOW_UNIFORM_LOCATION,
 };
 
 enum SkyUniformLocation {
@@ -109,17 +110,24 @@ struct RenderDataGLES3 {
 	const PagedArray<RID> *reflection_probes = nullptr;
 	RID environment;
 	RID camera_attributes;
+	RID shadow_atlas;
 	RID reflection_probe;
 	int reflection_probe_pass = 0;
 
 	float lod_distance_multiplier = 0.0;
 	float screen_mesh_lod_threshold = 0.0;
 
 	uint32_t directional_light_count = 0;
+	uint32_t directional_shadow_count = 0;
+
 	uint32_t spot_light_count = 0;
 	uint32_t omni_light_count = 0;
 
 	RenderingMethod::RenderInfo *render_info = nullptr;
+
+	/* Shadow data */
+	const RendererSceneRender::RenderShadowData *render_shadows = nullptr;
+	int render_shadow_count = 0;
 };
 
 class RasterizerCanvasGLES3;
@@ -173,11 +181,36 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 		float size;
 
 		uint32_t enabled; // For use by SkyShaders
-		float pad[2];
+		float pad;
+		float shadow_opacity;
 		float specular;
 	};
 	static_assert(sizeof(DirectionalLightData) % 16 == 0, "DirectionalLightData size must be a multiple of 16 bytes");
 
+	struct ShadowData {
+		float shadow_matrix[16];
+
+		float light_position[3];
+		float shadow_normal_bias;
+
+		float pad[3];
+		float shadow_atlas_pixel_size;
+	};
+	static_assert(sizeof(ShadowData) % 16 == 0, "ShadowData size must be a multiple of 16 bytes");
+
+	struct DirectionalShadowData {
+		float direction[3];
+		float shadow_atlas_pixel_size;
+		float shadow_normal_bias[4];
+		float shadow_split_offsets[4];
+		float shadow_matrices[4][16];
+		float fade_from;
+		float fade_to;
+		uint32_t blend_splits; // Not exposed to the shader.
+		uint32_t pad;
+	};
+	static_assert(sizeof(DirectionalShadowData) % 16 == 0, "DirectionalShadowData size must be a multiple of 16 bytes");
+
 	class GeometryInstanceGLES3;
 
 	// Cached data for drawing surfaces
@@ -221,6 +254,8 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 		uint32_t surface_index = 0;
 		uint32_t lod_index = 0;
 		uint32_t index_count = 0;
+		int32_t light_pass_index = -1;
+		bool finished_base_pass = false;
 
 		void *surface = nullptr;
 		GLES3::SceneShaderData *shader = nullptr;
@@ -245,14 +280,23 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 		bool using_projectors = false;
 		bool using_softshadows = false;
 
-		uint32_t omni_light_count = 0;
-		LocalVector<RID> omni_lights;
-		uint32_t spot_light_count = 0;
-		LocalVector<RID> spot_lights;
+		struct LightPass {
+			int32_t light_id = -1; // Position in the light uniform buffer.
+			int32_t shadow_id = -1; // Position in the shadow uniform buffer.
+			RID light_instance_rid;
+			bool is_omni = false;
+		};
+
+		LocalVector<LightPass> light_passes;
+
+		uint32_t paired_omni_light_count = 0;
+		uint32_t paired_spot_light_count = 0;
+		LocalVector<RID> paired_omni_lights;
+		LocalVector<RID> paired_spot_lights;
 		LocalVector<uint32_t> omni_light_gl_cache;
 		LocalVector<uint32_t> spot_light_gl_cache;
 
-		//used during setup
+		// Used during setup.
 		GeometryInstanceSurface *surface_caches = nullptr;
 		SelfList<GeometryInstanceGLES3> dirty_list_element;
 
@@ -336,10 +380,11 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 
 			float fog_light_color[3];
 			float fog_sun_scatter;
+
+			float shadow_bias;
+			float pad;
 			uint32_t camera_visible_layers;
-			uint32_t pad1;
-			uint32_t pad2;
-			uint32_t pad3;
+			bool pancake_shadows;
 		};
 		static_assert(sizeof(UBO) % 16 == 0, "Scene UBO size must be a multiple of 16 bytes");
 
@@ -378,16 +423,22 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 
 		LightData *omni_lights = nullptr;
 		LightData *spot_lights = nullptr;
+		ShadowData *positional_shadows = nullptr;
 
 		InstanceSort<GLES3::LightInstance> *omni_light_sort;
 		InstanceSort<GLES3::LightInstance> *spot_light_sort;
 		GLuint omni_light_buffer = 0;
 		GLuint spot_light_buffer = 0;
+		GLuint positional_shadow_buffer = 0;
 		uint32_t omni_light_count = 0;
 		uint32_t spot_light_count = 0;
+		RS::ShadowQuality positional_shadow_quality = RS::ShadowQuality::SHADOW_QUALITY_SOFT_LOW;
 
 		DirectionalLightData *directional_lights = nullptr;
 		GLuint directional_light_buffer = 0;
+		DirectionalShadowData *directional_shadows = nullptr;
+		GLuint directional_shadow_buffer = 0;
+		RS::ShadowQuality directional_shadow_quality = RS::ShadowQuality::SHADOW_QUALITY_SOFT_LOW;
 	} scene_state;
 
 	struct RenderListParameters {
@@ -462,9 +513,11 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 
 	RenderList render_list[RENDER_LIST_MAX];
 
-	void _setup_lights(const RenderDataGLES3 *p_render_data, bool p_using_shadows, uint32_t &r_directional_light_count, uint32_t &r_omni_light_count, uint32_t &r_spot_light_count);
-	void _setup_environment(const RenderDataGLES3 *p_render_data, bool p_no_fog, const Size2i &p_screen_size, bool p_flip_y, const Color &p_default_bg_color, bool p_pancake_shadows);
+	void _setup_lights(const RenderDataGLES3 *p_render_data, bool p_using_shadows, uint32_t &r_directional_light_count, uint32_t &r_omni_light_count, uint32_t &r_spot_light_count, uint32_t &r_directional_shadow_count);
+	void _setup_environment(const RenderDataGLES3 *p_render_data, bool p_no_fog, const Size2i &p_screen_size, bool p_flip_y, const Color &p_default_bg_color, bool p_pancake_shadows, float p_shadow_bias = 0.0);
 	void _fill_render_list(RenderListType p_render_list, const RenderDataGLES3 *p_render_data, PassMode p_pass_mode, bool p_append = false);
+	void _render_shadows(const RenderDataGLES3 *p_render_data);
+	void _render_shadow_pass(RID p_light, RID p_shadow_atlas, int p_pass, const PagedArray<RenderGeometryInstance *> &p_instances, const Plane &p_camera_plane = Plane(), float p_lod_distance_multiplier = 0, float p_screen_mesh_lod_threshold = 0.0, RenderingMethod::RenderInfo *p_render_info = nullptr);
 
 	template <PassMode p_pass_mode>
 	_FORCE_INLINE_ void _render_list_template(RenderListParameters *p_params, const RenderDataGLES3 *p_render_data, uint32_t p_from_element, uint32_t p_to_element, bool p_alpha_pass = false);
@@ -477,7 +530,7 @@ class RasterizerSceneGLES3 : public RendererSceneRender {
 	float screen_space_roughness_limiter_amount = 0.25;
 	float screen_space_roughness_limiter_limit = 0.18;
 
-	void _render_buffers_debug_draw(Ref<RenderSceneBuffersGLES3> p_render_buffers, RID p_shadow_atlas, RID p_occlusion_buffer);
+	void _render_buffers_debug_draw(Ref<RenderSceneBuffersGLES3> p_render_buffers, RID p_shadow_atlas);
 
 	/* Camera Attributes */
 

drivers/gles3/shaders/copy.glsl

@@ -6,6 +6,7 @@ mode_copy_section = #define USE_COPY_SECTION \n#define MODE_SIMPLE_COPY
 mode_gaussian_blur = #define MODE_GAUSSIAN_BLUR
 mode_mipmap = #define MODE_MIPMAP
 mode_simple_color = #define MODE_SIMPLE_COLOR \n#define USE_COPY_SECTION
+mode_cube_to_octahedral = #define CUBE_TO_OCTAHEDRAL \n#define USE_COPY_SECTION
 
 #[specializations]
 
@@ -50,8 +51,20 @@ uniform vec4 color_in;
 uniform highp vec2 pixel_size;
 #endif
 
+#ifdef CUBE_TO_OCTAHEDRAL
+uniform samplerCube source_cube; // texunit:0
+
+vec3 oct_to_vec3(vec2 e) {
+	vec3 v = vec3(e.xy, 1.0 - abs(e.x) - abs(e.y));
+	float t = max(-v.z, 0.0);
+	v.xy += t * -sign(v.xy);
+	return normalize(v);
+}
+#else
 uniform sampler2D source; // texunit:0
 
+#endif
+
 layout(location = 0) out vec4 frag_color;
 
 void main() {
@@ -90,4 +103,11 @@ void main() {
 	frag_color += (F + G + L + K) * lesser_weight;
 	frag_color += (G + H + M + L) * lesser_weight;
 #endif
+
+#ifdef CUBE_TO_OCTAHEDRAL
+	// Treat the UV coordinates as 0-1 encoded octahedral coordinates.
+	vec3 dir = oct_to_vec3(uv_interp * 2.0 - 1.0);
+	frag_color = texture(source_cube, dir);
+
+#endif
 }