This function will add 3D position data to the vertex currently being defined for the custom primitive. You supply the buffer to write the data into as well as the x, y and z position for drawing.
vertex_position_3d(buffer, x, y, z);
|buffer||The buffer to write the information to.|
|x||The x position.|
|y||The y position.|
|z||The z position.|
vertex_position_3d(buff, x - 100, y - 125, 0);
The above code will set the position of the vertex being defined.