Framebuffer
Framebuffers represent a collection of memory attachments that are used by a render pass instance. Examples of these memory attachments include the color textures and depth texture.
Creation
A framebuffer provides the attachments that a RenderPass needs while rendering.
// Create Render Target FrameBuffer
var rTColorTargetDescription = new TextureDescription()
{
Format = PixelFormat.R8G8B8A8_UNorm,
Width = rtSize,
Height = rtSize,
Depth = 1,
ArraySize = 1,
Faces = 1,
Flags = TextureFlags.RenderTarget | TextureFlags.ShaderResource,
CpuAccess = ResourceCpuAccess.None,
MipLevels = 1,
Type = TextureType.Texture2D,
Usage = ResourceUsage.Default,
SampleCount = TextureSampleCount.None,
};
var rTColorTarget = this.graphicsContext.Factory.CreateTexture(ref rTColorTargetDescription);
var rTDepthTargetDescription = new TextureDescription()
{
Format = PixelFormat.D24_UNorm_S8_UInt,
Width = rtSize,
Height = rtSize,
Depth = 1,
ArraySize = 1,
Faces = 1,
Flags = TextureFlags.DepthStencil,
CpuAccess = ResourceCpuAccess.None,
MipLevels = 1,
Type = TextureType.Texture2D,
Usage = ResourceUsage.Default,
SampleCount = TextureSampleCount.None,
};
var rTDepthTarget = this.graphicsContext.Factory.CreateTexture(ref rTDepthTargetDescription);
var depthAttachment = new FrameBufferAttachment(rTDepthTarget, 0, 1);
var colorsAttachment = new[] { new FrameBufferAttachment(rTColorTarget, 0, 1) };
this.rTFrameBuffer = this.graphicsContext.Factory.CreateFrameBuffer(depthAttachment, colorsAttachment);
How to use
First, you need to create a graphics pipeline that use the framebuffer output description:
var trianglePipelineDescription = new GraphicsPipelineDescription()
{
PrimitiveTopology = PrimitiveTopology.TriangleList,
InputLayouts = triangleVertexLayouts,
ResourceLayouts = new[] { triangleResourceLayout },
Shaders = new GraphicsShaderStateDescription()
{
VertexShader = triangleVertexShader,
PixelShader = trianglePixelShader,
},
RenderStates = new RenderStateDescription()
{
RasterizerState = RasterizerStates.None,
BlendState = BlendStates.Opaque,
DepthStencilState = DepthStencilStates.None,
},
Outputs = this.rTFrameBuffer.OutputDescription,
};
this.trianglePipelineState = this.graphicsContext.Factory.CreateGraphicsPipeline(ref trianglePipelineDescription);
And finally you can use to start a renderpass:
// Render to texture
var commandBuffer = this.commandQueue.CommandBuffer();
commandBuffer.Begin();
RenderPassDescription renderPassDescription = new RenderPassDescription(this.rTFrameBuffer, new ClearValue(ClearFlags.Target, Color.CornflowerBlue));
commandBuffer.BeginRenderPass(ref renderPassDescription);
commandBuffer.SetViewports(this.rTViewports);
commandBuffer.SetScissorRectangles(this.scissors);
commandBuffer.SetGraphicsPipelineState(this.trianglePipelineState);
commandBuffer.SetResourceSet(this.triangleResourceSet);
commandBuffer.SetVertexBuffers(this.triangleVertexBuffers);
commandBuffer.Draw((uint)this.triangleVertexData.Length);
commandBuffer.EndRenderPass();
commandBuffer.End();
commandBuffer.Commit();
this.commandQueue.Submit();
this.commandQueue.WaitIdle();