From 9f38535a3de0f42af189b602a97ac0239bb0a531 Mon Sep 17 00:00:00 2001
From: cosmonaut <evan@moonside.games>
Date: Wed, 27 Jan 2021 15:45:15 -0800
Subject: [PATCH] primitive types and rasterizer

---
 .../GraphicsPipeline/PrimitiveType.md         | 19 +++++++++++
 .../GraphicsPipeline/RasterizerState.md       | 32 +++++++++++++++++++
 2 files changed, 51 insertions(+)
 create mode 100644 content/Graphics/Resources/GraphicsPipeline/PrimitiveType.md
 create mode 100644 content/Graphics/Resources/GraphicsPipeline/RasterizerState.md

diff --git a/content/Graphics/Resources/GraphicsPipeline/PrimitiveType.md b/content/Graphics/Resources/GraphicsPipeline/PrimitiveType.md
new file mode 100644
index 0000000..b9f94aa
--- /dev/null
+++ b/content/Graphics/Resources/GraphicsPipeline/PrimitiveType.md
@@ -0,0 +1,19 @@
+---
+title: "PrimitiveType"
+date: 2021-01-27T15:32:11-08:00
+weight: 5
+---
+
+`PrimitiveType` determines how a stream of vertex information will be interpreted as shapes by the pipeline. There are 5 types of primitives that MoonWorks supports.
+
+`PointList` will interpret the data as a list of points.
+
+`LineList` will interpret the data as a list of lines.
+
+`LineStrip` will interpet the data as a strip of lines.
+
+`TriangleList` will interpret the data as a list of triangles.
+
+`TriangleStrip` will interpret the data as a strip of triangles.
+
+The primitive type you will use the most by far is `TriangleList` - the vast majority of 3D model exporters will give you vertex data in the form of a list of triangles. The others are mostly niche cases.
diff --git a/content/Graphics/Resources/GraphicsPipeline/RasterizerState.md b/content/Graphics/Resources/GraphicsPipeline/RasterizerState.md
new file mode 100644
index 0000000..cb2a1ed
--- /dev/null
+++ b/content/Graphics/Resources/GraphicsPipeline/RasterizerState.md
@@ -0,0 +1,32 @@
+---
+title: "Rasterizer State"
+date: 2021-01-27T15:30:01-08:00
+weight: 6
+---
+
+Rasterization is, essentially, the process of converting 3D vertex information into pixels on a surface. There are many different ways that we may wish to control rasterization.
+
+Note that I am mostly going to discuss triangles here. Many of these options will be ignored unless you are using triangle primitives, for soon to be obvious reasons.
+
+`FrontFace` specifies which triangles we will designate as "front-facing", using what we call "winding order". If we use `FrontFace.CounterClockwise`, then triangles listed in counter-clockwise order will be designated as front faces. Likewise, if we use `FrontFace.Clockwise`, clockwise triangles will be designated as front faces. Which order you choose depends on the format of your vertex data.
+
+Why is this important? The answer is "primitive culling". A lot of the time we have no need to render triangles that are facing away from the camera, so we can save a lot of processing time by not rasterizing those triangles.
+
+`CullMode` has four options: `None`, `Front`, `Back`, and `FrontAndBack`.
+
+`FillMode` tells the rasterizer how to fill in the triangles. `Fill` completely fills the triangle. `Line` only renders the edges of the face. `Point` only renders the input points. `Line` mode is also referred to as "wireframe rendering" which is useful for debugging.
+
+`LineWidth` describes lines in terms of pixel width. Maximum line width above 1f is hardware-specific so be careful with this one.
+
+Finally, the rasterizer can alter depth values by adding a constant factor or biasing them based on slope. This can sometimes be useful for shadow mapping. Most of the time you won't be needing this and you can just set `DepthBiasEnable` to false.
+
+```cs
+var myRasterizerState = new RasterizerState
+{
+    FrontFace = FrontFace.Clockwise,
+    CullMode = CullMode.Back,
+    FillMode = FillMode.Fill,
+    LineWidth = 1f,
+    DepthBiasEnable = false
+};
+```