Add Graphics::RenderInstance, bind instance SSBO during draw

Author: karnkaul

App/Src/Main.cpp

@@ -2,6 +2,8 @@
 #include <Tkge/Engine.hpp>
 #include <Tkge/Graphics/Shader.hpp>
 #include <klib/assert.hpp>
+#include <kvf/time.hpp>
+#include <cmath>
 #include <exception>
 #include <print>
 
@@ -51,10 +53,10 @@ namespace
 		if (!shader.Load(renderDevice.get_device(), vertexSpirV, fragmentSpirV)) { throw std::runtime_error{"Failed to load shaders"}; }
 
 		static constexpr auto Vertices = std::array{
-			Tkge::Graphics::Vertex{.position = {-200.0f, -200.0f}, .colour = kvf::red_v.to_vec4()},
-			Tkge::Graphics::Vertex{.position = {200.0f, -200.0f}, .colour = kvf::green_v.to_vec4()},
-			Tkge::Graphics::Vertex{.position = {200.0f, 200.0f}, .colour = kvf::blue_v.to_vec4()},
-			Tkge::Graphics::Vertex{.position = {-200.0f, 200.0f}, .colour = kvf::yellow_v.to_vec4()},
+			Tkge::Graphics::Vertex{.position = {-200.0f, -200.0f}},
+			Tkge::Graphics::Vertex{.position = {200.0f, -200.0f}},
+			Tkge::Graphics::Vertex{.position = {200.0f, 200.0f}},
+			Tkge::Graphics::Vertex{.position = {-200.0f, 200.0f}},
 		};
 
 		static constexpr auto Indices = std::array{
@@ -66,13 +68,28 @@ namespace
 			.indices = Indices,
 		};
 
+		auto instances = std::array<Tkge::Graphics::RenderInstance, 2>{};
+		instances[0].transform.position.x = -250.0f;
+		instances[0].tint = kvf::cyan_v;
+		instances[1].transform.position.x = 250.0f;
+		instances[1].tint = kvf::yellow_v;
+
 		auto wireframe = false;
 		auto lineWidth = 3.0f;
 
+		auto deltaTime = kvf::DeltaTime{};
+		auto elapsed = kvf::Seconds{};
+
 		while (engine.IsRunning())
 		{
 			engine.NextFrame();
 
+			const auto dt = deltaTime.tick();
+			elapsed += dt;
+
+			instances[0].tint.w = kvf::Color::to_u8((0.5f * std::sin(elapsed.count())) + 0.5f);
+			instances[1].tint.w = kvf::Color::to_u8((0.5f * std::sin(-elapsed.count())) + 0.5f);
+
 			if (ImGui::Begin("Misc"))
 			{
 				ImGui::Checkbox("wireframe", &wireframe);
@@ -85,7 +102,7 @@ namespace
 				renderer.BindShader(shader);
 				renderer.SetLineWidth(lineWidth);
 				renderer.SetWireframe(wireframe);
-				renderer.Draw(Primitive);
+				renderer.Draw(Primitive, instances);
 			}
 
 			engine.Present();

Assets/Shaders/Default.vert

@@ -0,0 +1,12 @@
+#pragma once
+#include <Tkge/Transform.hpp>
+#include <kvf/color.hpp>
+
+namespace Tkge::Graphics
+{
+	struct RenderInstance
+	{
+		Transform transform{};
+		kvf::Color tint{kvf::white_v};
+	};
+} // namespace Tkge::Graphics

Lib/Include/Tkge/Graphics/RenderInstance.hpp

@@ -1,5 +1,6 @@
 #pragma once
 #include <Tkge/Graphics/Primitive.hpp>
+#include <Tkge/Graphics/RenderInstance.hpp>
 #include <Tkge/Graphics/ResourcePool.hpp>
 #include <Tkge/Transform.hpp>
 #include <kvf/render_pass.hpp>
@@ -26,15 +27,22 @@ namespace Tkge::Graphics
 		void SetLineWidth(float width);
 		void SetWireframe(bool wireframe);
 
-		void Draw(const Primitive& primitive);
+		void Draw(const Primitive& primitive, std::span<const RenderInstance> instances);
 
 		explicit operator bool() const { return IsRendering(); }
 
 		Transform view{};
 
 	  private:
+		struct Std430Instance
+		{
+			glm::mat4 model;
+			glm::vec4 tint;
+		};
+
+		void UpdateInstances(std::span<const RenderInstance> instances);
 		[[nodiscard]] bool WriteSets() const;
-		void BindVboAndDraw(const Primitive& primitive) const;
+		void BindVboAndDraw(const Primitive& primitive, std::uint32_t instances) const;
 
 		kvf::RenderPass* _renderPass{};
 		IResourcePool* _resourcePool{};
@@ -45,5 +53,6 @@ namespace Tkge::Graphics
 		vk::Pipeline _pipeline{};
 		vk::PolygonMode _polygonMode{vk::PolygonMode::eFill};
 		float _lineWidth{1.0f};
+		std::vector<Std430Instance> _instances{};
 	};
 } // namespace Tkge::Graphics

Lib/Include/Tkge/Graphics/Renderer.hpp

@@ -75,10 +75,12 @@ namespace Tkge::Detail
 		{
 			static constexpr auto StageFlags = vk::ShaderStageFlagBits::eAllGraphics;
 			// set 0: builtin
-			auto set0 = std::array<vk::DescriptorSetLayoutBinding, 1>{};
+			auto set0 = std::array<vk::DescriptorSetLayoutBinding, 2>{};
 			// set 0, binding 0: view
 			set0[0].setBinding(0).setDescriptorCount(1).setDescriptorType(vk::DescriptorType::eUniformBuffer).setStageFlags(StageFlags);
-			// TODO: instances, texture bindings
+			// set 0, binding 1: instances
+			set0[1].setBinding(1).setDescriptorCount(1).setDescriptorType(vk::DescriptorType::eStorageBuffer).setStageFlags(StageFlags);
+			// TODO: texture bindings
 
 			// TODO: set 1: user data
 

Lib/Src/Detail/PipelinePool.hpp

@@ -1,5 +1,11 @@
 #version 450 core
 
+struct Instance
+{
+	mat4 model;
+	vec4 tint;
+};
+
 layout (location = 0) in vec2 aPos;
 layout (location = 1) in vec4 aColour;
 layout (location = 2) in vec2 aUv;
@@ -9,11 +15,20 @@ layout (set = 0, binding = 0) uniform View
 	mat4 matVP;
 };
 
+layout (set = 0, binding = 1) readonly buffer Instances
+{
+	Instance instances[];
+};
+
 layout (location = 0) out vec4 outColour;
 
 void main()
 {
-	outColour = aColour;
+	const Instance instance = instances[gl_InstanceIndex];
+
+	const vec4 worldPos = instance.model * vec4(aPos, 0.0, 1.0);
+
+	outColour = aColour * instance.tint;
 
-	gl_Position = matVP * vec4(aPos, 0.0, 1.0);
+	gl_Position = matVP * worldPos;
 }

Lib/Src/Glsl/Default.vert

@@ -29,18 +29,18 @@ namespace Tkge::Graphics
 		return true;
 	}
 
-	void Renderer::SetWireframe(const bool wireframe) { _polygonMode = wireframe ? vk::PolygonMode::eLine : vk::PolygonMode::eFill; }
-
 	void Renderer::SetLineWidth(const float width)
 	{
 		if (_renderPass == nullptr) { return; }
 		const auto limits = _renderPass->get_render_device().get_gpu().properties.limits.lineWidthRange;
 		_lineWidth = std::clamp(width, limits[0], limits[1]);
 	}
 
-	void Renderer::Draw(const Primitive& primitive)
+	void Renderer::SetWireframe(const bool wireframe) { _polygonMode = wireframe ? vk::PolygonMode::eLine : vk::PolygonMode::eFill; }
+
+	void Renderer::Draw(const Primitive& primitive, std::span<const RenderInstance> instances)
 	{
-		if (!IsRendering() || _shader == nullptr || primitive.vertices.empty()) { return; }
+		if (!IsRendering() || _shader == nullptr || primitive.vertices.empty() || instances.empty()) { return; }
 
 		const auto fixedState = PipelineFixedState{
 			.colourFormat = _renderPass->get_color_format(),
@@ -56,11 +56,22 @@ namespace Tkge::Graphics
 			_renderPass->bind_pipeline(_pipeline);
 		}
 
+		UpdateInstances(instances);
 		if (!WriteSets()) { return; }
 
 		_renderPass->get_command_buffer().setViewport(0, _viewport);
 
-		BindVboAndDraw(primitive);
+		BindVboAndDraw(primitive, std::uint32_t(instances.size()));
+	}
+
+	void Renderer::UpdateInstances(std::span<const RenderInstance> instances)
+	{
+		_instances.clear();
+		_instances.reserve(instances.size());
+		for (const auto& instance : instances)
+		{
+			_instances.push_back(Std430Instance{.model = instance.transform.ToModel(), .tint = instance.tint.to_linear()});
+		}
 	}
 
 	bool Renderer::WriteSets() const
@@ -91,6 +102,11 @@ namespace Tkge::Graphics
 		kvf::util::overwrite(ubo00, matVP);
 		pushBufferWrite(descriptorSets[0], 0, ubo00, vk::DescriptorType::eUniformBuffer);
 
+		const auto instanceSpan = std::span{_instances};
+		auto& ssbo01 = _resourcePool->AllocateBuffer(vk::BufferUsageFlagBits::eStorageBuffer, instanceSpan.size_bytes());
+		kvf::util::overwrite(ssbo01, instanceSpan);
+		pushBufferWrite(descriptorSets[0], 1, ssbo01, vk::DescriptorType::eStorageBuffer);
+
 		const auto writeSpan = std::span{descriptorWrites.data(), descriptorWrites.size()};
 		renderDevice.get_device().updateDescriptorSets(writeSpan, {});
 
@@ -100,7 +116,7 @@ namespace Tkge::Graphics
 		return true;
 	}
 
-	void Renderer::BindVboAndDraw(const Primitive& primitive) const
+	void Renderer::BindVboAndDraw(const Primitive& primitive, const std::uint32_t instances) const
 	{
 		const auto vertSize = primitive.vertices.size_bytes();
 		const auto vboSize = vertSize + primitive.indices.size_bytes();
@@ -112,11 +128,11 @@ namespace Tkge::Graphics
 		commandBuffer.setLineWidth(_lineWidth);
 
 		commandBuffer.bindVertexBuffers(0, vertexBuffer.get_buffer(), vk::DeviceSize{});
-		if (primitive.indices.empty()) { commandBuffer.draw(std::uint32_t(primitive.vertices.size()), 1, 0, 0); }
+		if (primitive.indices.empty()) { commandBuffer.draw(std::uint32_t(primitive.vertices.size()), instances, 0, 0); }
 		else
 		{
 			commandBuffer.bindIndexBuffer(vertexBuffer.get_buffer(), vertSize, vk::IndexType::eUint32);
-			commandBuffer.drawIndexed(std::uint32_t(primitive.indices.size()), 1, 0, 0, 0);
+			commandBuffer.drawIndexed(std::uint32_t(primitive.indices.size()), instances, 0, 0, 0);
 		}
 	}
 } // namespace Tkge::Graphics