Calculating a point inside a polygon

Question

Let's say that we have a 3d polygon that is defined with three points

• x1, y1, z1
• x2, y2, z2
• x3, y3, z3

Then we have a perpendicular to the Z axis ray with position rX, rY. How can we find out if the ray is hitting the polygon and in what X,Y,Z the collision is happening.

Any code example will be very useful.

Answer 1

For intersection of a vector with a triangle in 3D, see http://en.wikipedia.org/wiki/M%C3%B6ller%E2%80%93Trumbore_intersection_algorithm . You'll need to add your own cross-product (CROSS), dot-product (DOT), and sub-vector (SUB) code for the pseudo-code.