Merge pull request #109084 from allenwp/add-spatial-shader-debanding

Add material debanding for use in Mobile rendering method.

doc/classes/ProjectSettings.xml

@@ -2770,9 +2770,9 @@
 			[b]Note:[/b] This property is only read when the project starts. There is currently no way to change this setting at run-time.
 		</member>
 		<member name="rendering/anti_aliasing/quality/use_debanding" type="bool" setter="" getter="" default="false">
-			If [code]true[/code], uses a fast post-processing filter to make banding significantly less visible. If [member rendering/viewport/hdr_2d] is [code]false[/code], 2D rendering is [i]not[/i] affected by debanding unless the [member Environment.background_mode] is [constant Environment.BG_CANVAS]. If [member rendering/viewport/hdr_2d] is [code]true[/code], debanding will affect all 2D and 3D rendering, including canvas items.
+			If [code]true[/code], uses a fast dithering filter just before transforming floating point color values to integer color values to make banding significantly less visible. Debanding is applied at different steps of the rendering process depending on the rendering method and [member rendering/viewport/hdr_2d] setting.
 			In some cases, debanding may introduce a slightly noticeable dithering pattern. It's recommended to enable debanding only when actually needed since the dithering pattern will make lossless-compressed screenshots larger.
-			[b]Note:[/b] This property is only read when the project starts. To set debanding at runtime, set [member Viewport.use_debanding] on the root [Viewport] instead, or use [method RenderingServer.viewport_set_use_debanding].
+			[b]Note:[/b] This property is only read when the project starts and configures [method RenderingServer.material_set_use_debanding] and [member Viewport.use_debanding] of the root [Viewport]. When [member rendering/viewport/hdr_2d] is disabled, you should additionally set the [member Viewport.use_debanding] of other viewports in your project. To set debanding at run-time, the property that should be set depends on the renderer: Forward+ only uses [member Viewport.use_debanding] and Mobile uses both [method RenderingServer.material_set_use_debanding] and [member Viewport.use_debanding].
 		</member>
 		<member name="rendering/anti_aliasing/quality/use_taa" type="bool" setter="" getter="" default="false">
 			Enables temporal antialiasing for the default screen [Viewport]. TAA works by jittering the camera and accumulating the images of the last rendered frames, motion vector rendering is used to account for camera and object motion. Enabling TAA can make the image blurrier, which is partially counteracted by automatically using a negative mipmap LOD bias (see [member rendering/textures/default_filters/texture_mipmap_bias]).

doc/classes/RenderingServer.xml

@@ -2360,6 +2360,15 @@
 				Sets a shader material's shader.
 			</description>
 		</method>
+		<method name="material_set_use_debanding">
+			<return type="void" />
+			<param index="0" name="enable" type="bool" />
+			<description>
+				When using the Mobile renderer, [method material_set_use_debanding] can be used to enable or disable the debanding feature of 3D materials ([BaseMaterial3D] and [ShaderMaterial]).
+				[method material_set_use_debanding] has no effect when using the Compatibility or Forward+ renderer. In Forward+, [Viewport] debanding can be used instead.
+				See also [member ProjectSettings.rendering/anti_aliasing/quality/use_debanding] and [method RenderingServer.viewport_set_use_debanding].
+			</description>
+		</method>
 		<method name="mesh_add_surface">
 			<return type="void" />
 			<param index="0" name="mesh" type="RID" />

doc/classes/Viewport.xml

@@ -457,9 +457,9 @@
 			[b]Note:[/b] Due to technical limitations, certain rendering features are disabled when a viewport has a transparent background. This currently applies to screen-space reflections, subsurface scattering, and depth of field.
 		</member>
 		<member name="use_debanding" type="bool" setter="set_use_debanding" getter="is_using_debanding" default="false">
-			If [code]true[/code], uses a fast post-processing filter to make banding significantly less visible. If [member use_hdr_2d] is [code]false[/code], 2D rendering is [i]not[/i] affected by debanding unless the [member Environment.background_mode] is [constant Environment.BG_CANVAS]. If [member use_hdr_2d] is [code]true[/code], debanding will only be applied if this is the root [Viewport] and will affect all 2D and 3D rendering, including canvas items.
-			In some cases, debanding may introduce a slightly noticeable dithering pattern. It's recommended to enable debanding only when actually needed since the dithering pattern will make lossless-compressed screenshots larger.
-			See also [member ProjectSettings.rendering/anti_aliasing/quality/use_debanding] and [method RenderingServer.viewport_set_use_debanding].
+			When using the Mobile or Forward+ renderers, set [member use_debanding] to enable or disable the debanding feature of this [Viewport]. If [member use_hdr_2d] is [code]false[/code], 2D rendering is [i]not[/i] affected by debanding unless the [member Environment.background_mode] is [constant Environment.BG_CANVAS]. If [member use_hdr_2d] is [code]true[/code], debanding will only be applied if this is the root [Viewport] and will affect all 2D and 3D rendering, including canvas items.
+			[member use_debanding] has no effect when using the Compatibility rendering method. The Mobile renderer can also use material debanding, which can be set with [method RenderingServer.material_set_use_debanding] or configured with [member ProjectSettings.rendering/anti_aliasing/quality/use_debanding].
+			See also [member ProjectSettings.rendering/anti_aliasing/quality/use_debanding], [method RenderingServer.material_set_use_debanding], and [method RenderingServer.viewport_set_use_debanding].
 		</member>
 		<member name="use_hdr_2d" type="bool" setter="set_use_hdr_2d" getter="is_using_hdr_2d" default="false">
 			If [code]true[/code], 2D rendering will use a high dynamic range (HDR) format framebuffer matching the bit depth of the 3D framebuffer. When using the Forward+ or Compatibility renderer, this will be an [code]RGBA16[/code] framebuffer. When using the Mobile renderer, it will be an [code]RGB10_A2[/code] framebuffer.

drivers/gles3/rasterizer_scene_gles3.cpp

@@ -4288,6 +4288,10 @@ void RasterizerSceneGLES3::lightmaps_set_bicubic_filter(bool p_enable) {
 	lightmap_bicubic_upscale = p_enable;
 }
 
+void RasterizerSceneGLES3::material_set_use_debanding(bool p_enable) {
+	// Material debanding not yet implemented.
+}
+
 RasterizerSceneGLES3::RasterizerSceneGLES3() {
 	singleton = this;
 

drivers/gles3/rasterizer_scene_gles3.h

@@ -950,6 +950,7 @@ public:
 	void decals_set_filter(RS::DecalFilter p_filter) override;
 	void light_projectors_set_filter(RS::LightProjectorFilter p_filter) override;
 	virtual void lightmaps_set_bicubic_filter(bool p_enable) override;
+	virtual void material_set_use_debanding(bool p_enable) override;
 
 	RasterizerSceneGLES3();
 	~RasterizerSceneGLES3();

editor/editor_node.cpp

@@ -527,6 +527,7 @@ void EditorNode::_update_from_settings() {
 	RS::get_singleton()->decals_set_filter(RS::DecalFilter(int(GLOBAL_GET("rendering/textures/decals/filter"))));
 	RS::get_singleton()->light_projectors_set_filter(RS::LightProjectorFilter(int(GLOBAL_GET("rendering/textures/light_projectors/filter"))));
 	RS::get_singleton()->lightmaps_set_bicubic_filter(GLOBAL_GET("rendering/lightmapping/lightmap_gi/use_bicubic_filter"));
+	RS::get_singleton()->material_set_use_debanding(GLOBAL_GET("rendering/anti_aliasing/quality/use_debanding"));
 
 	SceneTree *tree = get_tree();
 	tree->set_debug_collisions_color(GLOBAL_GET("debug/shapes/collision/shape_color"));

scene/main/scene_tree.cpp

@@ -2086,7 +2086,7 @@ SceneTree::SceneTree() {
 	const bool use_taa = GLOBAL_DEF_BASIC("rendering/anti_aliasing/quality/use_taa", false);
 	root->set_use_taa(use_taa);
 
-	const bool use_debanding = GLOBAL_DEF("rendering/anti_aliasing/quality/use_debanding", false);
+	const bool use_debanding = GLOBAL_GET("rendering/anti_aliasing/quality/use_debanding");
 	root->set_use_debanding(use_debanding);
 
 	const bool use_occlusion_culling = GLOBAL_DEF("rendering/occlusion_culling/use_occlusion_culling", false);

servers/rendering/dummy/rasterizer_scene_dummy.h

@@ -193,6 +193,7 @@ public:
 	virtual void decals_set_filter(RS::DecalFilter p_filter) override {}
 	virtual void light_projectors_set_filter(RS::LightProjectorFilter p_filter) override {}
 	virtual void lightmaps_set_bicubic_filter(bool p_enable) override {}
+	virtual void material_set_use_debanding(bool p_enable) override {}
 
 	RasterizerSceneDummy() {}
 	~RasterizerSceneDummy() {}

servers/rendering/renderer_rd/forward_mobile/render_forward_mobile.cpp

@@ -3329,6 +3329,7 @@ void RenderForwardMobile::_update_shader_quality_settings() {
 			light_projectors_get_filter() == RS::LIGHT_PROJECTOR_FILTER_LINEAR_MIPMAPS_ANISOTROPIC;
 
 	specialization.use_lightmap_bicubic_filter = lightmap_filter_bicubic_get();
+	specialization.use_material_debanding = material_use_debanding_get();
 	specialization.luminance_multiplier = 2.0f;
 	scene_shader.set_default_specialization(specialization);
 

servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.h

@@ -89,21 +89,27 @@ public:
 				uint32_t use_light_soft_shadows : 1;
 				uint32_t use_directional_soft_shadows : 1;
 				uint32_t decal_use_mipmaps : 1;
+
 				uint32_t projector_use_mipmaps : 1;
 				uint32_t disable_fog : 1;
 				uint32_t use_depth_fog : 1;
 				uint32_t use_fog_aerial_perspective : 1;
+
 				uint32_t use_fog_sun_scatter : 1;
 				uint32_t use_fog_height_density : 1;
 				uint32_t use_lightmap_bicubic_filter : 1;
+				uint32_t use_material_debanding : 1;
+
 				uint32_t multimesh : 1;
 				uint32_t multimesh_format_2d : 1;
 				uint32_t multimesh_has_color : 1;
 				uint32_t multimesh_has_custom_data : 1;
+
 				uint32_t scene_use_ambient_cubemap : 1;
 				uint32_t scene_use_reflection_cubemap : 1;
 				uint32_t scene_roughness_limiter_enabled : 1;
-				uint32_t padding_0 : 2;
+				uint32_t padding_0 : 1;
+
 				uint32_t soft_shadow_samples : 6;
 				uint32_t penumbra_shadow_samples : 6;
 			};

servers/rendering/renderer_rd/renderer_scene_render_rd.cpp

@@ -1248,6 +1248,11 @@ void RendererSceneRenderRD::lightmaps_set_bicubic_filter(bool p_enable) {
 	_update_shader_quality_settings();
 }
 
+void RendererSceneRenderRD::material_set_use_debanding(bool p_enable) {
+	material_use_debanding = p_enable;
+	_update_shader_quality_settings();
+}
+
 int RendererSceneRenderRD::get_roughness_layers() const {
 	return sky.roughness_layers;
 }
@@ -1702,6 +1707,7 @@ void RendererSceneRenderRD::init() {
 	decals_set_filter(RS::DecalFilter(int(GLOBAL_GET("rendering/textures/decals/filter"))));
 	light_projectors_set_filter(RS::LightProjectorFilter(int(GLOBAL_GET("rendering/textures/light_projectors/filter"))));
 	lightmaps_set_bicubic_filter(GLOBAL_GET("rendering/lightmapping/lightmap_gi/use_bicubic_filter"));
+	material_set_use_debanding(GLOBAL_GET("rendering/anti_aliasing/quality/use_debanding"));
 
 	cull_argument.set_page_pool(&cull_argument_pool);
 

servers/rendering/renderer_rd/renderer_scene_render_rd.h

@@ -154,6 +154,7 @@ private:
 	int soft_shadow_samples = 0;
 	RS::DecalFilter decals_filter = RS::DECAL_FILTER_LINEAR_MIPMAPS;
 	RS::LightProjectorFilter light_projectors_filter = RS::LIGHT_PROJECTOR_FILTER_LINEAR_MIPMAPS;
+	bool material_use_debanding = false;
 
 	/* RENDER BUFFERS */
 
@@ -278,6 +279,7 @@ public:
 	virtual void decals_set_filter(RS::DecalFilter p_filter) override;
 	virtual void light_projectors_set_filter(RS::LightProjectorFilter p_filter) override;
 	virtual void lightmaps_set_bicubic_filter(bool p_enable) override;
+	virtual void material_set_use_debanding(bool p_enable) override;
 
 	_FORCE_INLINE_ RS::ShadowQuality shadows_quality_get() const {
 		return shadows_quality;
@@ -328,6 +330,10 @@ public:
 		return decals_filter;
 	}
 
+	_FORCE_INLINE_ bool material_use_debanding_get() const {
+		return material_use_debanding;
+	}
+
 	int get_roughness_layers() const;
 	bool is_using_radiance_cubemap_array() const;
 

servers/rendering/renderer_rd/shaders/forward_mobile/scene_forward_mobile.glsl

@@ -2225,6 +2225,28 @@ void main() {
 
 	frag_color = out_color;
 
+	if (sc_use_material_debanding()) {
+		// From https://alex.vlachos.com/graphics/Alex_Vlachos_Advanced_VR_Rendering_GDC2015.pdf
+		// and https://www.shadertoy.com/view/MslGR8 (5th one starting from the bottom)
+		// NOTE: `gl_FragCoord` is in pixels (i.e. not normalized UV).
+		// This dithering must be applied after encoding changes (linear/nonlinear) have been applied
+		// as the final step before quantization from floating point to integer values.
+
+		// Iestyn's RGB dither (7 asm instructions) from Portal 2 X360, slightly modified for VR.
+		// Removed the time component to avoid passing time into this shader.
+		// This dither offset was chosen because it meshes nicely with the no-offset dither that
+		// is used for Viewport debanding.
+		const vec2 dither_offset = vec2(0.535, 8.715);
+		vec3 dither = vec3(dot(vec2(171.0, 231.0), gl_FragCoord.xy + dither_offset));
+		dither.rgb = fract(dither.rgb / vec3(103.0, 71.0, 97.0));
+
+		// Subtract 0.5 to avoid slightly brightening the whole viewport.
+		// Use a dither strength of 100% rather than the 37.5% suggested by the original source.
+		// Assume that this shader always writes to a 10-bit buffer, so divide by 1023 to align
+		// to 10-bit quantization.
+		frag_color.rgb += (dither.rgb - 0.5) / 1023.0;
+	}
+
 #endif //MODE_MULTIPLE_RENDER_TARGETS
 
 #endif //MODE_RENDER_DEPTH

servers/rendering/renderer_rd/shaders/forward_mobile/scene_forward_mobile_inc.glsl

@@ -116,34 +116,38 @@ bool sc_use_lightmap_bicubic_filter() {
 	return ((sc_packed_0() >> 10) & 1U) != 0;
 }
 
-bool sc_multimesh() {
+bool sc_use_material_debanding() {
 	return ((sc_packed_0() >> 11) & 1U) != 0;
 }
 
-bool sc_multimesh_format_2d() {
+bool sc_multimesh() {
 	return ((sc_packed_0() >> 12) & 1U) != 0;
 }
 
-bool sc_multimesh_has_color() {
+bool sc_multimesh_format_2d() {
 	return ((sc_packed_0() >> 13) & 1U) != 0;
 }
 
-bool sc_multimesh_has_custom_data() {
+bool sc_multimesh_has_color() {
 	return ((sc_packed_0() >> 14) & 1U) != 0;
 }
 
-bool sc_scene_use_ambient_cubemap() {
+bool sc_multimesh_has_custom_data() {
 	return ((sc_packed_0() >> 15) & 1U) != 0;
 }
 
-bool sc_scene_use_reflection_cubemap() {
+bool sc_scene_use_ambient_cubemap() {
 	return ((sc_packed_0() >> 16) & 1U) != 0;
 }
 
-bool sc_scene_roughness_limiter_enabled() {
+bool sc_scene_use_reflection_cubemap() {
 	return ((sc_packed_0() >> 17) & 1U) != 0;
 }
 
+bool sc_scene_roughness_limiter_enabled() {
+	return ((sc_packed_0() >> 18) & 1U) != 0;
+}
+
 uint sc_soft_shadow_samples() {
 	return (sc_packed_0() >> 20) & 63U;
 }

servers/rendering/renderer_scene_cull.h

@@ -1390,6 +1390,7 @@ public:
 	PASS1(decals_set_filter, RS::DecalFilter)
 	PASS1(light_projectors_set_filter, RS::LightProjectorFilter)
 	PASS1(lightmaps_set_bicubic_filter, bool)
+	PASS1(material_set_use_debanding, bool)
 
 	virtual void update();
 

servers/rendering/renderer_scene_render.h

@@ -342,6 +342,7 @@ public:
 	virtual void decals_set_filter(RS::DecalFilter p_filter) = 0;
 	virtual void light_projectors_set_filter(RS::LightProjectorFilter p_filter) = 0;
 	virtual void lightmaps_set_bicubic_filter(bool p_enable) = 0;
+	virtual void material_set_use_debanding(bool p_enable) = 0;
 
 	virtual void update() = 0;
 	virtual ~RendererSceneRender() {}

servers/rendering/rendering_method.h

@@ -355,6 +355,7 @@ public:
 	virtual void decals_set_filter(RS::DecalFilter p_filter) = 0;
 	virtual void light_projectors_set_filter(RS::LightProjectorFilter p_filter) = 0;
 	virtual void lightmaps_set_bicubic_filter(bool p_enable) = 0;
+	virtual void material_set_use_debanding(bool p_enable) = 0;
 
 	virtual bool free(RID p_rid) = 0;
 

servers/rendering/rendering_server.cpp

@@ -2341,6 +2341,8 @@ void RenderingServer::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("material_set_next_pass", "material", "next_material"), &RenderingServer::material_set_next_pass);
 
+	ClassDB::bind_method(D_METHOD("material_set_use_debanding", "enable"), &RenderingServer::material_set_use_debanding);
+
 	BIND_CONSTANT(MATERIAL_RENDER_PRIORITY_MIN);
 	BIND_CONSTANT(MATERIAL_RENDER_PRIORITY_MAX);
 
@@ -3698,6 +3700,8 @@ void RenderingServer::init() {
 
 	GLOBAL_DEF_RST(PropertyInfo(Variant::FLOAT, "rendering/anti_aliasing/quality/smaa_edge_detection_threshold", PROPERTY_HINT_RANGE, "0.01,0.2,0.01"), 0.05);
 
+	GLOBAL_DEF("rendering/anti_aliasing/quality/use_debanding", false);
+
 	{
 		String mode_hints;
 		String mode_hints_metal;

servers/rendering/rendering_server.h

@@ -271,6 +271,8 @@ public:
 
 	virtual void material_set_next_pass(RID p_material, RID p_next_material) = 0;
 
+	virtual void material_set_use_debanding(bool p_enable) = 0;
+
 	/* MESH API */
 
 	enum ArrayType {

servers/rendering/rendering_server_default.h

@@ -853,6 +853,7 @@ public:
 	FUNC1(decals_set_filter, RS::DecalFilter);
 	FUNC1(light_projectors_set_filter, RS::LightProjectorFilter);
 	FUNC1(lightmaps_set_bicubic_filter, bool);
+	FUNC1(material_set_use_debanding, bool);
 
 	/* CAMERA ATTRIBUTES */