Rendering a quad, facing a normal

Yes. You need two vectors perpendicular to the normal, let's call them Up and Right. These can be obtained for example using cross product. Given a unit-length normal vector N:

// epsilon is something like 1e-3// we do this to prevent floating-point inaccuracies// also, cross(v,v) is a null vector which we don't wantif(N.y < 1-epsilon)  Right = cross(N, (0,1,0))else  Right = cross(N, (1,0,0))Up = cross(Right, N)

Now, the vertices for the quad are (if you want the quad centered around the point of impact):

V1 = Point - Up/2 - Right/2V2 = Point - Up/2 + Right/2V3 = Point + Up/2 + Right/2V4 = Point + Up/2 - Right/2

Thanks :)