add(/wiki/t-junction): barely acceptable content-wise; missing references?

Author: Longor1996

content/wiki/t-junction/index.md

@@ -0,0 +1,23 @@
++++
+title = "T-Junctions"
+description = "Any vertex placed on an edge creates infinitely small gaps in geometry."
+[taxonomies]
+categories = ["math"]
+tags = ["math", "meshing"]
++++
+
+Any time your meshing process results in the corner of a triangle
+resting on the edge of another triangle, you get a **T-Junction**.
+
+While this gap between the corner and the edge *is* infinitely small mathematically,
+it *absolutely isn't* in practice, due to floating-point computation and rounding.
+
+<span style="color:red">This **always** happens</span>,
+even if you've managed eliminate *all* floating-point errors.
+
+There are four ways to work around this issue:
+
+1. Expand the faces ever so slightly outwards.
+2. Fill the pixel-wide gaps in a post-process shader.
+3. Don't create geometry where vertices can lie on edges.
+4. Directly raytrace your voxel volume.