1234567891011121314151617181920 |
- vec3 get_unit_normal(vec3 p0, vec3 p1, vec3 p2){
- float tol = 1e-6;
- vec3 v1 = normalize(p1 - p0);
- vec3 v2 = normalize(p2 - p0);
- vec3 cp = cross(v1, v2);
- float cp_norm = length(cp);
- if(cp_norm > tol) return cp / cp_norm;
- // Otherwise, three pionts form a line, so find
- // a normal vector to that line in the plane shared
- // with the z-axis
- vec3 comb = v1 + v2;
- cp = cross(cross(comb, vec3(0.0, 0.0, 1.0)), comb);
- cp_norm = length(cp);
- if(cp_norm > tol) return cp / cp_norm;
- // Otherwise, the points line up with the z-axis.
- return vec3(0.0, -1.0, 0.0);
- }
|