The input file for Triangle World is in ascii and describes the triangles in your scene as follows:

N
x₀   y₀   z₀   r₀   g₀   b₀
x₁   y₁   z₁   r₁   g₁   b₁
...
x_N-1   y_N-1   z_N-1   r_N-1   g_N-1   b_N-1
M
u₀   v₀   w₀
u₁   v₁   w₁
...
u_M-1   v_M-1   w_M-1


where N is the number of vertices, M is the number of triangles, x_i, y_i, z_i are floats representing the coordinates of vertex i, r_i, g_i, b_i is the color of vertex i, and u_j, v_j, w_j are integers representing indices in the vertex list of the vertices in triangle j as they appear from the front of the triangle in counter-clockwise order.

The following file models a 1x1 red rectangle in the x-y plane facing the positive-z direction with a corner at the origin.
4
0 0 0 1 0 0
1 0 0 1 0 0
1 1 0 1 0 0
0 1 0 1 0 0
2
0 1 2
0 2 3