Introduction
I'm reading on surface geometry[1], as an entrypoint into ray tracing. I've also been reading on web GPU fundamentals, GPUs generally and how computer graphics work.
Tetrahedron
A tetrahedron has four triangular faces. This means it has four vertices, you can think of them as X, Y, Z and origin coordinates. It also has six edges.
Triangles are important in computer graphics because any surface can be built as a set of triangles called a mesh.
OFF and Mesh
OFF[2] is a simple binary protocol that lets you define your vertices and faces. In the case of a tethrahedron, the off file looks like:
OFF
4 4 0
1.0 0.0 0.0
0.0 1.0 0.0
0.0 0.0 1.0
0.0 0.0 0.0
3 0 1 2
3 0 2 3
3 0 1 3
3 1 2 34 4 0 - means 4 vertices, 4 faces and 0 edges (ignored).
The next four lines define the co-ordinates of the vertices.
Eg. 1.0 0.0 0.0 - means the (X, Y, Z) coordinates.
The subsequent four lines define each face and which vertices combine to form it.
Eg 3 0 1 2 - means this face is a combination of 3 vertices. Vertices at index 0, 1 and 2.
Mesh is the library used to import and render the OFF file. Other file formats exist like OBJ.
The rendered tetrahedron looks like:
