I am trying to convert a ray hit on an infinite plane, defined by an origin and a normal vector, into UV coordinates, so I can find the appropriate texel at that point.
Code I have is close to functional, however, when the plane has a normal of (0, 0, -1) the result is a plain white plane.
The code that calculates the UV coordinates is pasted below:
// Calculate UV coordinates for the texture vec3 u = vec3( normal.y, -normal.x, 0 ).normalized(); vec3 v = normal.cross( u ); h.u = u.dot( h.coordinates ); h.v = v.dot( h.coordinates );
h is a Hit struct that stores relevant data from a ray-primitive intersection, coordinates is the vec3 where the intersection occurred.
The current situation is shown in the following image; The floor plane properly shows the texture, however, the back wall does not.
However, when I change the normal of the back wall ever so slightly, the texture appears
In image 1 the normal of the back plane was (0, 0, -1), while it was (0.0001, 0, -1) in the second image.
I have been trying to figure this one out, but I am hitting a dead end.