QuadRenderer.cs

using System;
using System.Numerics;
using System.Text;
using Veldrid;
using Veldrid.SPIRV;

namespace Desolation.Graphics
{
    public unsafe class QuadRenderer : IDisposable
    {
        private const string VertexCode = @"
#version 450

layout (location = 0) in vec3 Position;
layout (location = 1) in vec4 Color;
layout (location = 2) in vec2 TexCoords;

layout(set = 0, binding = 0) uniform vTransformBuffer
{
    mat4x4 transform;
};

layout (location = 0) out vec4 fColor;
layout (location = 1) out vec2 fTexCoords;

void main()
{
    gl_Position = transform * vec4(Position, 1.00);
    fColor = Color;
    fTexCoords = TexCoords;
}";

        private const string FragmentCode = @"
#version 450

layout (location = 0) in vec4 fColor;
layout (location = 1) in vec2 fTexCoords;

layout(set = 1, binding = 0) uniform texture2D fTexture;
layout(set = 1, binding = 1) uniform sampler fTextureSampler;

layout (location = 0) out vec4 fOutColor;

void main()
{
    fOutColor = texture(sampler2D(fTexture, fTextureSampler), fTexCoords) * fColor;
}";

        private readonly DeviceBuffer vertexBuffer;

        private readonly DeviceBuffer indexBuffer;

        private readonly DeviceBuffer transformBuffer;

        private readonly Shader[] shaders;

        private readonly Pipeline pipeline;

        private readonly ResourceSet transformSet;

        private readonly ResourceSet textureSet;

        public QuadRenderer(GraphicsDevice graphicsDevice, Texture texture, TextureView textureView)
        {
            var factory = graphicsDevice.ResourceFactory;

            this.transformBuffer = factory.CreateBuffer(new BufferDescription((uint)sizeof(Matrix4x4), BufferUsage.UniformBuffer));

            var quadVertices = new[]
            {
                new VertexPositionColorTexCoords(new Vector3(-0.75f, -0.75f, 0.00f), RgbaByte.Blue, new Vector2(0.00f, 0.00f)),
                new VertexPositionColorTexCoords(new Vector3(+0.75f, -0.75f, 0.00f), RgbaByte.Yellow, new Vector2(1.00f, 0.00f)),
                new VertexPositionColorTexCoords(new Vector3(-0.75f, +0.75f, 0.00f), RgbaByte.Red, new Vector2(0.00f, 1.00f)),
                new VertexPositionColorTexCoords(new Vector3(+0.75f, +0.75f, 0.00f), RgbaByte.Green, new Vector2(1.00f, 1.00f)),
            };
            this.vertexBuffer = factory.CreateBuffer(new BufferDescription((uint)(quadVertices.Length * sizeof(VertexPositionColorTexCoords)), BufferUsage.VertexBuffer));
            graphicsDevice.UpdateBuffer(this.vertexBuffer, 0, quadVertices);

            ushort[] quadIndices = { 0, 1, 2, 1, 3, 2 };
            this.indexBuffer = factory.CreateBuffer(new BufferDescription((uint)(quadIndices.Length * sizeof(ushort)), BufferUsage.IndexBuffer));
            graphicsDevice.UpdateBuffer(this.indexBuffer, 0, quadIndices);

            var vertexShaderDesc = new ShaderDescription(ShaderStages.Vertex, Encoding.UTF8.GetBytes(VertexCode), "main");
            var fragmentShaderDesc = new ShaderDescription(ShaderStages.Fragment, Encoding.UTF8.GetBytes(FragmentCode), "main");

            this.shaders = factory.CreateFromSpirv(vertexShaderDesc, fragmentShaderDesc, new CrossCompileOptions(false, true));

            var transformLayout = factory.CreateResourceLayout(
                new ResourceLayoutDescription(
                    new ResourceLayoutElementDescription("vTransformBuffer", ResourceKind.UniformBuffer, ShaderStages.Vertex)));

            this.transformSet = factory.CreateResourceSet(new ResourceSetDescription(transformLayout, this.transformBuffer));

            var textureLayout = factory.CreateResourceLayout(
                new ResourceLayoutDescription(
                    new ResourceLayoutElementDescription("fTexture", ResourceKind.TextureReadOnly, ShaderStages.Fragment),
                    new ResourceLayoutElementDescription("fTextureSampler", ResourceKind.Sampler, ShaderStages.Fragment)));

            this.textureSet = factory.CreateResourceSet(new ResourceSetDescription(textureLayout, textureView, graphicsDevice.Aniso4xSampler));

            // Create pipeline
            var pipelineDescription = new GraphicsPipelineDescription
            {
                BlendState = BlendStateDescription.SingleOverrideBlend,
                DepthStencilState = new DepthStencilStateDescription(depthTestEnabled: true, depthWriteEnabled: true, comparisonKind: ComparisonKind.LessEqual),
                RasterizerState = new RasterizerStateDescription(cullMode: FaceCullMode.None, fillMode: PolygonFillMode.Solid, frontFace: FrontFace.Clockwise, depthClipEnabled: true, scissorTestEnabled: false),
                PrimitiveTopology = PrimitiveTopology.TriangleStrip,
                ShaderSet = new ShaderSetDescription(vertexLayouts: new[] { VertexPositionColorTexCoords.VertexLayoutDescription }, shaders: this.shaders),
                ResourceLayouts = new[] { transformLayout, textureLayout },
                Outputs = graphicsDevice.SwapchainFramebuffer.OutputDescription,
            };

            this.pipeline = factory.CreateGraphicsPipeline(pipelineDescription);
        }

        public void Render(CommandList commandList)
        {
            commandList.UpdateBuffer(this.transformBuffer, 0, Matrix4x4.Identity);

            // Set all relevant state to draw our quad.
            commandList.SetVertexBuffer(0, this.vertexBuffer);
            commandList.SetIndexBuffer(this.indexBuffer, IndexFormat.UInt16);
            commandList.SetPipeline(this.pipeline);

            commandList.SetGraphicsResourceSet(0, this.transformSet);
            commandList.SetGraphicsResourceSet(1, this.textureSet);

            // Issue a Draw command for a single instance with 6 indices.
            commandList.DrawIndexed(indexCount: 6, instanceCount: 1, indexStart: 0, vertexOffset: 0, instanceStart: 0);
        }

        public void Dispose()
        {
            this.pipeline.Dispose();
            foreach (var shader in this.shaders)
            {
                shader.Dispose();
            }
            this.indexBuffer.Dispose();
            this.vertexBuffer.Dispose();
        }
    }
}