MoonWorks-docs/content/Graphics/Resources/GraphicsPipeline/AttachmentInfo.md

title	date	weight
Attachment Info	2021-01-28T12:55:51-08:00	10

GraphicsPipelineAttachmentInfo tells the graphics pipeline what kinds of render passes will be used with the pipeline. These are compatible render passes. It also describes how the pipeline should blend colors. Blending does not affect compatibility, but the other properties do.

This structure is composed of a set of ColorAttachmentDescriptions, and an optional depth/stencil format.

Each ColorAttachmentDescription is composed of a texture format, a multisample count, and a ColorAttachmentBlendState.

Our color attachment always has color information stored in it - the blend state tells the renderer how to combine new pixel values with the original values to produce a new color.

BlendEnable is a bool. If we turn off blending entirely, the new pixel color will just overwrite any existing values. Simple!

ColorWriteMask tells the renderer which color channels it is allowed to write to.

Next we have AlphaBlendOp and ColorBlendOp, which are BlendOp values, and the rest of the fields are BlendFactor values. Rather than spend a bunch of time explaining the nuances of various blend modes, I will simply link you to a very thorough explanation of graphics blending.

Here is an example blend mode, which does something we call "additive blending". This kind of blending is very useful for lighting and particle effects.

var myColorTargetBlendState = new ColorTargetBlendState
{
    BlendEnable = true,
    ColorWriteMask = ColorComponentFlags.RGBA,
    AlphaBlendOp = BlendOp.Add,
    ColorBlendOp = BlendOp.Add,
    SourceColorBlendFactor = BlendFactor.SourceAlpha,
    SourceAlphaBlendFactor = BlendFactor.SourceAlpha,
    DestinationColorBlendFactor = BlendFactor.One,
    DestinationAlphaBlendFactor = BlendFactor.One
};