add(/wiki/quad-indices): stubbed article with diagram

Author: Longor1996

content/wiki/quad-indices/index.md

@@ -1,12 +1,44 @@
 +++
 title = "Quad Indices"
 description = "The basic pattern of indices for quads made of triangles."
-draft = true
 [taxonomies]
 categories = []
 tags = ["meshing"]
 +++
 
-> The basic pattern of indices for quads made of triangles.
+A **quadliteral** (also called **quad**, **tetragon** or **quadrangle**) is a four-sided polygon, with four corners/vertices and four edges/sides.
 
-{{ stub_notice() }}
+Unfortunately, GPUs/rasterizers generally only deal with triangles,
+so we'll have to split each one of our quads into two triangles...
+resulting in two of the vertices being duplicated.
+
+Since we don't like pointless duplication, we ought to use an **element/index-buffer**,
+which tells the GPU how to assemble two triangles from four vertices each.
+
+But how do we assign/number/order the four vertices?
+
+{% figure(caption="**Diagram of Winding Orders:** Clockwise, Counter-Clockwise, Z-Order, N-Order",author="Lars Longor K",license="CC0",class="full") %}/wiki/quad-indices/windings.svg{% end %}
+
+## Clockwise Winding
+
+{{stub_notice(kind="section")}}
+
+## Counter-Clockwise Winding
+
+> The opposite/inverse of clockwise order.
+
+{{stub_notice(kind="section")}}
+
+## Z-Order Winding
+
+{{stub_notice(kind="section")}}
+
+## N-Order Winding
+
+> The opposite/inverse of Z-order.
+
+{{stub_notice(kind="section")}}
+
+## References
+
+- <https://en.wikipedia.org/wiki/Quadrilateral>