Implement support for fragment density maps.

Co-Authored-By: Bastiaan Olij <mux213@gmail.com>

drivers/d3d12/rendering_device_driver_d3d12.h

@@ -825,7 +825,7 @@ class RenderingDeviceDriverD3D12 : public RenderingDeviceDriver {
 	};
 
 public:
-	virtual RenderPassID render_pass_create(VectorView<Attachment> p_attachments, VectorView<Subpass> p_subpasses, VectorView<SubpassDependency> p_subpass_dependencies, uint32_t p_view_count) override final;
+	virtual RenderPassID render_pass_create(VectorView<Attachment> p_attachments, VectorView<Subpass> p_subpasses, VectorView<SubpassDependency> p_subpass_dependencies, uint32_t p_view_count, AttachmentReference p_fragment_density_map_attachment) override final;
 	virtual void render_pass_free(RenderPassID p_render_pass) override final;
 
 	// ----- COMMANDS -----

drivers/vulkan/rendering_device_driver_vulkan.h

@@ -76,10 +76,10 @@ class RenderingDeviceDriverVulkan : public RenderingDeviceDriver {
 		String supported_operations_desc() const;
 	};
 
-	struct VRSCapabilities {
-		bool pipeline_vrs_supported = false; // We can specify our fragment rate on a pipeline level.
-		bool primitive_vrs_supported = false; // We can specify our fragment rate on each drawcall.
-		bool attachment_vrs_supported = false; // We can provide a density map attachment on our framebuffer.
+	struct FSRCapabilities {
+		bool pipeline_fsr_supported = false; // We can specify our fragment rate on a pipeline level.
+		bool primitive_fsr_supported = false; // We can specify our fragment rate on each drawcall.
+		bool attachment_fsr_supported = false; // We can provide a density map attachment on our framebuffer.
 
 		Size2i min_texel_size;
 		Size2i max_texel_size;
@@ -88,6 +88,16 @@ class RenderingDeviceDriverVulkan : public RenderingDeviceDriver {
 		Size2i texel_size; // The texel size we'll use
 	};
 
+	struct FDMCapabilities {
+		bool fragment_density_map = false;
+		bool fragment_density_map_dynamic = false;
+		bool fragment_density_map_non_submsampled_images = false;
+
+		Size2i min_fragment_density_texel_size;
+		Size2i max_fragment_density_texel_size;
+		bool fragment_density_invocations = false;
+	};
+
 	struct ShaderCapabilities {
 		bool shader_float16_is_supported = false;
 		bool shader_int8_is_supported = false;
@@ -135,7 +145,8 @@ class RenderingDeviceDriverVulkan : public RenderingDeviceDriver {
 	RDD::Capabilities device_capabilities;
 	SubgroupCapabilities subgroup_capabilities;
 	MultiviewCapabilities multiview_capabilities;
-	VRSCapabilities vrs_capabilities;
+	FSRCapabilities fsr_capabilities;
+	FDMCapabilities fdm_capabilities;
 	ShaderCapabilities shader_capabilities;
 	StorageBufferCapabilities storage_buffer_capabilities;
 	bool pipeline_cache_control_support = false;
@@ -560,7 +571,7 @@ class RenderingDeviceDriverVulkan : public RenderingDeviceDriver {
 
 	// ----- SUBPASS -----
 
-	virtual RenderPassID render_pass_create(VectorView<Attachment> p_attachments, VectorView<Subpass> p_subpasses, VectorView<SubpassDependency> p_subpass_dependencies, uint32_t p_view_count) override final;
+	virtual RenderPassID render_pass_create(VectorView<Attachment> p_attachments, VectorView<Subpass> p_subpasses, VectorView<SubpassDependency> p_subpass_dependencies, uint32_t p_view_count, AttachmentReference p_fragment_density_map_attachment) override final;
 	virtual void render_pass_free(RenderPassID p_render_pass) override final;
 
 	// ----- COMMANDS -----

servers/rendering/renderer_rd/effects/vrs.cpp

@@ -44,6 +44,8 @@ VRS::VRS() {
 		Vector<String> vrs_modes;
 		vrs_modes.push_back("\n"); // VRS_DEFAULT
 		vrs_modes.push_back("\n#define USE_MULTIVIEW\n"); // VRS_MULTIVIEW
+		vrs_modes.push_back("\n#define SPLIT_RG\n"); // VRS_RG
+		vrs_modes.push_back("\n#define SPLIT_RG\n#define USE_MULTIVIEW\n"); // VRS_RG_MULTIVIEW
 
 		vrs_shader.shader.initialize(vrs_modes);
 
@@ -80,15 +82,19 @@ void VRS::copy_vrs(RID p_source_rd_texture, RID p_dest_framebuffer, bool p_multi
 
 	RD::Uniform u_source_rd_texture(RD::UNIFORM_TYPE_SAMPLER_WITH_TEXTURE, 0, Vector<RID>({ default_sampler, p_source_rd_texture }));
 
+	int mode = 0;
 	VRSPushConstant push_constant = {};
-
-	int mode = p_multiview ? VRS_MULTIVIEW : VRS_DEFAULT;
-
-	// Set maximum texel factor based on maximum fragment size, some GPUs do not support 8x8 (fragment shading rate approach).
-	if (MIN(RD::get_singleton()->limit_get(RD::LIMIT_VRS_MAX_FRAGMENT_WIDTH), RD::get_singleton()->limit_get(RD::LIMIT_VRS_MAX_FRAGMENT_HEIGHT)) > 4) {
-		push_constant.max_texel_factor = 3.0;
+	if (RD::get_singleton()->has_feature(RD::SUPPORTS_FRAGMENT_DENSITY_MAP)) {
+		mode = p_multiview ? VRS_RG_MULTIVIEW : VRS_RG;
 	} else {
-		push_constant.max_texel_factor = 2.0;
+		mode = p_multiview ? VRS_MULTIVIEW : VRS_DEFAULT;
+
+		// Set maximum texel factor based on maximum fragment size, some GPUs do not support 8x8 (fragment shading rate approach).
+		if (MIN(RD::get_singleton()->limit_get(RD::LIMIT_FRAGMENT_SHADING_RATE_MAX_FRAGMENT_WIDTH), RD::get_singleton()->limit_get(RD::LIMIT_FRAGMENT_SHADING_RATE_MAX_FRAGMENT_HEIGHT)) > 4) {
+			push_constant.max_texel_factor = 3.0;
+		} else {
+			push_constant.max_texel_factor = 2.0;
+		}
 	}
 
 	RID shader = vrs_shader.shader.version_get_shader(vrs_shader.shader_version, mode);
@@ -103,8 +109,16 @@ void VRS::copy_vrs(RID p_source_rd_texture, RID p_dest_framebuffer, bool p_multi
 }
 
 Size2i VRS::get_vrs_texture_size(const Size2i p_base_size) const {
-	int32_t texel_width = RD::get_singleton()->limit_get(RD::LIMIT_VRS_TEXEL_WIDTH);
-	int32_t texel_height = RD::get_singleton()->limit_get(RD::LIMIT_VRS_TEXEL_HEIGHT);
+	int32_t texel_width = 0;
+	int32_t texel_height = 0;
+	if (RD::get_singleton()->has_feature(RD::SUPPORTS_FRAGMENT_DENSITY_MAP)) {
+		const int32_t PreferredTexelSize = 32;
+		texel_width = CLAMP(PreferredTexelSize, RD::get_singleton()->limit_get(RD::LIMIT_MIN_FRAGMENT_DENSITY_TEXEL_WIDTH), RD::get_singleton()->limit_get(RD::LIMIT_MAX_FRAGMENT_DENSITY_TEXEL_WIDTH));
+		texel_height = CLAMP(PreferredTexelSize, RD::get_singleton()->limit_get(RD::LIMIT_MIN_FRAGMENT_DENSITY_TEXEL_HEIGHT), RD::get_singleton()->limit_get(RD::LIMIT_MAX_FRAGMENT_DENSITY_TEXEL_HEIGHT));
+	} else {
+		texel_width = RD::get_singleton()->limit_get(RD::LIMIT_FRAGMENT_SHADING_RATE_TEXEL_WIDTH);
+		texel_height = RD::get_singleton()->limit_get(RD::LIMIT_FRAGMENT_SHADING_RATE_TEXEL_HEIGHT);
+	}
 
 	int width = p_base_size.x / texel_width;
 	if (p_base_size.x % texel_width != 0) {

servers/rendering/renderer_rd/effects/vrs.h

@@ -44,6 +44,8 @@ class VRS {
 	enum VRSMode {
 		VRS_DEFAULT,
 		VRS_MULTIVIEW,
+		VRS_RG,
+		VRS_RG_MULTIVIEW,
 		VRS_MAX,
 	};
 

servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.cpp

@@ -143,7 +143,6 @@ RID RenderForwardClustered::RenderBufferDataForwardClustered::get_color_only_fb(
 
 	if (render_buffers->has_texture(RB_SCOPE_VRS, RB_TEXTURE)) {
 		RID vrs_texture = render_buffers->get_texture(RB_SCOPE_VRS, RB_TEXTURE);
-
 		return FramebufferCacheRD::get_singleton()->get_cache_multiview(render_buffers->get_view_count(), color, depth, vrs_texture);
 	} else {
 		return FramebufferCacheRD::get_singleton()->get_cache_multiview(render_buffers->get_view_count(), color, depth);
@@ -173,7 +172,6 @@ RID RenderForwardClustered::RenderBufferDataForwardClustered::get_color_pass_fb(
 
 	if (render_buffers->has_texture(RB_SCOPE_VRS, RB_TEXTURE)) {
 		RID vrs_texture = render_buffers->get_texture(RB_SCOPE_VRS, RB_TEXTURE);
-
 		return FramebufferCacheRD::get_singleton()->get_cache_multiview(v_count, color, specular, velocity_buffer, depth, vrs_texture);
 	} else {
 		return FramebufferCacheRD::get_singleton()->get_cache_multiview(v_count, color, specular, velocity_buffer, depth);

servers/rendering/renderer_rd/forward_mobile/render_forward_mobile.cpp

@@ -172,6 +172,7 @@ RID RenderForwardMobile::RenderBufferDataForwardMobile::get_color_fbs(Framebuffe
 
 	uint32_t view_count = render_buffers->get_view_count();
 
+	bool vrs_uses_fdm = RD::get_singleton()->has_feature(RD::SUPPORTS_FRAGMENT_DENSITY_MAP);
 	RID vrs_texture;
 	if (render_buffers->has_texture(RB_SCOPE_VRS, RB_TEXTURE)) {
 		vrs_texture = render_buffers->get_texture(RB_SCOPE_VRS, RB_TEXTURE);
@@ -199,8 +200,8 @@ RID RenderForwardMobile::RenderBufferDataForwardMobile::get_color_fbs(Framebuffe
 			RD::FramebufferPass pass;
 			pass.color_attachments.push_back(0);
 			pass.depth_attachment = 1;
-			if (vrs_texture.is_valid()) {
-				pass.vrs_attachment = 2;
+			if (!vrs_uses_fdm && vrs_texture.is_valid()) {
+				pass.fragment_shading_rate_attachment = 2;
 			}
 
 			if (use_msaa) {
@@ -222,8 +223,8 @@ RID RenderForwardMobile::RenderBufferDataForwardMobile::get_color_fbs(Framebuffe
 			RD::FramebufferPass pass;
 			pass.color_attachments.push_back(0);
 			pass.depth_attachment = 1;
-			if (vrs_texture.is_valid()) {
-				pass.vrs_attachment = 2;
+			if (!vrs_uses_fdm && vrs_texture.is_valid()) {
+				pass.fragment_shading_rate_attachment = 2;
 			}
 
 			if (use_msaa) {
@@ -2864,8 +2865,9 @@ static RD::FramebufferFormatID _get_color_framebuffer_format_for_pipeline(RD::Da
 	pass.color_attachments.push_back(0);
 	pass.depth_attachment = 1;
 
-	if (p_vrs) {
-		pass.vrs_attachment = 2;
+	bool vrs_uses_fdm = RD::get_singleton()->has_feature(RD::SUPPORTS_FRAGMENT_DENSITY_MAP);
+	if (!vrs_uses_fdm && p_vrs) {
+		pass.fragment_shading_rate_attachment = 2;
 	}
 
 	if (multisampling) {
@@ -2893,7 +2895,7 @@ static RD::FramebufferFormatID _get_color_framebuffer_format_for_pipeline(RD::Da
 		passes.push_back(blit_pass);
 	}
 
-	return RD::get_singleton()->framebuffer_format_create_multipass(attachments, passes, p_view_count);
+	return RD::get_singleton()->framebuffer_format_create_multipass(attachments, passes, p_view_count, vrs_uses_fdm ? 2 : -1);
 }
 
 static RD::FramebufferFormatID _get_reflection_probe_color_framebuffer_format_for_pipeline() {

servers/rendering/renderer_rd/framebuffer_cache_rd.h

@@ -59,7 +59,7 @@ class FramebufferCacheRD : public Object {
 
 	static _FORCE_INLINE_ uint32_t _hash_pass(const RD::FramebufferPass &p, uint32_t h) {
 		h = hash_murmur3_one_32(p.depth_attachment, h);
-		h = hash_murmur3_one_32(p.vrs_attachment, h);
+		h = hash_murmur3_one_32(p.fragment_shading_rate_attachment, h);
 
 		h = hash_murmur3_one_32(p.color_attachments.size(), h);
 		for (int i = 0; i < p.color_attachments.size(); i++) {
@@ -84,7 +84,7 @@ class FramebufferCacheRD : public Object {
 			return false;
 		}
 
-		if (a.vrs_attachment != b.vrs_attachment) {
+		if (a.fragment_shading_rate_attachment != b.fragment_shading_rate_attachment) {
 			return false;
 		}
 

servers/rendering/renderer_rd/renderer_scene_render_rd.cpp

@@ -1424,7 +1424,7 @@ void RendererSceneRenderRD::sdfgi_set_debug_probe_select(const Vector3 &p_positi
 RendererSceneRenderRD *RendererSceneRenderRD::singleton = nullptr;
 
 bool RendererSceneRenderRD::is_vrs_supported() const {
-	return RD::get_singleton()->has_feature(RD::SUPPORTS_ATTACHMENT_VRS);
+	return RD::get_singleton()->has_feature(RD::SUPPORTS_ATTACHMENT_FRAGMENT_SHADING_RATE) || RD::get_singleton()->has_feature(RD::SUPPORTS_FRAGMENT_DENSITY_MAP);
 }
 
 bool RendererSceneRenderRD::is_dynamic_gi_supported() const {

servers/rendering/renderer_rd/shaders/effects/vrs.glsl

@@ -59,7 +59,11 @@ layout(location = 0) in vec2 uv_interp;
 layout(set = 0, binding = 0) uniform sampler2D source_color;
 #endif /* USE_MULTIVIEW */
 
+#ifdef SPLIT_RG
+layout(location = 0) out vec2 frag_color;
+#else
 layout(location = 0) out uint frag_color;
+#endif
 
 layout(push_constant, std430) uniform Params {
 	float max_texel_factor;
@@ -79,6 +83,12 @@ void main() {
 	// Input is standardized. R for X, G for Y, 0.0 (0) = 1, 0.33 (85) = 2, 0.66 (170) = 3, 1.0 (255) = 8
 	vec4 color = textureLod(source_color, uv, 0.0);
 
+#ifdef SPLIT_RG
+	// Density map for VRS according to VK_EXT_fragment_density_map, we can use as is.
+	// TODO: The format is different than was was described in the comment. Discuss with Baastian if we should
+	// bother doing a conversion here or just generate it differently on the CPU instead.
+	frag_color = max(vec2(1.0f) - color.rg, vec2(1.0f / 255.0f));
+#else
 	// Output image shading rate image for VRS according to VK_KHR_fragment_shading_rate.
 	color.r = clamp(floor(color.r * params.max_texel_factor + 0.1), 0.0, params.max_texel_factor);
 	color.g = clamp(floor(color.g * params.max_texel_factor + 0.1), 0.0, params.max_texel_factor);
@@ -94,4 +104,5 @@ void main() {
 	// Encode to frag_color;
 	frag_color = int(color.r + 0.1) << 2;
 	frag_color += int(color.g + 0.1);
+#endif
 }

servers/rendering/renderer_rd/storage_rd/render_scene_buffers_rd.cpp

@@ -725,9 +725,17 @@ uint32_t RenderSceneBuffersRD::get_velocity_usage_bits(bool p_resolve, bool p_ms
 }
 
 RD::DataFormat RenderSceneBuffersRD::get_vrs_format() {
-	return RD::DATA_FORMAT_R8_UINT;
+	if (RD::get_singleton()->has_feature(RD::SUPPORTS_FRAGMENT_DENSITY_MAP)) {
+		return RD::DATA_FORMAT_R8G8_UNORM;
+	} else {
+		return RD::DATA_FORMAT_R8_UINT;
+	}
 }
 
 uint32_t RenderSceneBuffersRD::get_vrs_usage_bits() {
-	return RD::TEXTURE_USAGE_COLOR_ATTACHMENT_BIT | RD::TEXTURE_USAGE_VRS_ATTACHMENT_BIT | RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_STORAGE_BIT;
+	if (RD::get_singleton()->has_feature(RD::SUPPORTS_FRAGMENT_DENSITY_MAP)) {
+		return RD::TEXTURE_USAGE_COLOR_ATTACHMENT_BIT | RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_STORAGE_BIT | RD::TEXTURE_USAGE_FRAGMENT_DENSITY_MAP_BIT;
+	} else {
+		return RD::TEXTURE_USAGE_COLOR_ATTACHMENT_BIT | RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_STORAGE_BIT | RD::TEXTURE_USAGE_FRAGMENT_SHADING_RATE_ATTACHMENT_BIT;
+	}
 }

servers/rendering/renderer_rd/storage_rd/texture_storage.cpp

@@ -482,9 +482,9 @@ TextureStorage::TextureStorage() {
 		tformat.format = RD::DATA_FORMAT_R8_UINT;
 		tformat.width = 4;
 		tformat.height = 4;
-		tformat.usage_bits = RD::TEXTURE_USAGE_COLOR_ATTACHMENT_BIT | RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_STORAGE_BIT | RD::TEXTURE_USAGE_CAN_UPDATE_BIT | RD::TEXTURE_USAGE_VRS_ATTACHMENT_BIT;
+		tformat.usage_bits = RD::TEXTURE_USAGE_COLOR_ATTACHMENT_BIT | RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_STORAGE_BIT | RD::TEXTURE_USAGE_CAN_UPDATE_BIT | RD::TEXTURE_USAGE_FRAGMENT_SHADING_RATE_ATTACHMENT_BIT;
 		tformat.texture_type = RD::TEXTURE_TYPE_2D;
-		if (!RD::get_singleton()->has_feature(RD::SUPPORTS_ATTACHMENT_VRS)) {
+		if (!RD::get_singleton()->has_feature(RD::SUPPORTS_ATTACHMENT_FRAGMENT_SHADING_RATE)) {
 			tformat.usage_bits = RD::TEXTURE_USAGE_COLOR_ATTACHMENT_BIT | RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_CAN_UPDATE_BIT;
 		}
 
@@ -501,6 +501,33 @@ TextureStorage::TextureStorage() {
 		}
 	}
 
+	{
+		// Create default fragment density map.
+		RD::TextureFormat tformat;
+		tformat.format = RD::DATA_FORMAT_R8G8_UNORM;
+		tformat.width = 4;
+		tformat.height = 4;
+		tformat.usage_bits = RD::TEXTURE_USAGE_COLOR_ATTACHMENT_BIT | RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_CAN_UPDATE_BIT;
+		tformat.texture_type = RD::TEXTURE_TYPE_2D;
+
+		if (RD::get_singleton()->has_feature(RD::SUPPORTS_FRAGMENT_DENSITY_MAP)) {
+			// Only request the usage bits if we know the feature is supported.
+			tformat.usage_bits |= RD::TEXTURE_USAGE_STORAGE_BIT | RD::TEXTURE_USAGE_FRAGMENT_DENSITY_MAP_BIT;
+		}
+
+		Vector<uint8_t> pv;
+		pv.resize(4 * 4);
+		for (int i = 0; i < 4 * 4; i++) {
+			pv.set(i, 0);
+		}
+
+		{
+			Vector<Vector<uint8_t>> vpv;
+			vpv.push_back(pv);
+			default_rd_textures[DEFAULT_RD_TEXTURE_FDM] = RD::get_singleton()->texture_create(tformat, RD::TextureView(), vpv);
+		}
+	}
+
 	{
 		Vector<String> sdf_modes;
 		sdf_modes.push_back("\n#define MODE_LOAD\n");

servers/rendering/renderer_rd/storage_rd/texture_storage.h

@@ -67,6 +67,7 @@ class TextureStorage : public RendererTextureStorage {
 		DEFAULT_RD_TEXTURE_2D_ARRAY_DEPTH,
 		DEFAULT_RD_TEXTURE_2D_UINT,
 		DEFAULT_RD_TEXTURE_VRS,
+		DEFAULT_RD_TEXTURE_FDM,
 		DEFAULT_RD_TEXTURE_MAX
 	};