diff options
Diffstat (limited to 'math_helper.c')
| -rw-r--r-- | math_helper.c | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/math_helper.c b/math_helper.c index b6e0cb3..9ae2c9e 100644 --- a/math_helper.c +++ b/math_helper.c @@ -20,6 +20,24 @@ int orientation(vec2f p, vec2f q, vec2f r) return (val > 0)? 1: 2; // clock or counterclock wise } +vec2f get_dir_of_line(vec2f p1, vec2f p2) { + float dirx = (p1.x - p2.x); + float diry = (p1.y - p2.y); + double length = sqrt(dirx * dirx + diry * diry); + dirx /= length; + diry /= length; + return (vec2f){dirx, diry}; +} + +bool neg2(float p1, float p2) { + return p1 < 0.0f && p2 < 0.0f || abs(p1-p2) < 1.0f; +} + +bool pos2(float p1, float p2) { + return (p1 >= 0.0f && p2 >= 0.0f) || abs(p1-p2) < 1.0f; +} + + bool lines_intersect(vec2f p1, vec2f q1, vec2f p2, vec2f q2) { int o1 = orientation(p1, q1, p2); @@ -28,8 +46,14 @@ bool lines_intersect(vec2f p1, vec2f q1, vec2f p2, vec2f q2) int o4 = orientation(p2, q2, q1); // General case - if (o1 != o2 && o3 != o4) - return true; + if (o1 != o2 && o3 != o4) { + vec2f bdir = get_dir_of_line(p1, q1); + vec2f pdir = get_dir_of_line(p1, p2); + if ((neg2(bdir.x, pdir.x) || pos2(bdir.x, pdir.x)) && (neg2(bdir.y, pdir.y) || pos2(bdir.y, pdir.y))) return true; // going down + //return true; + + //return false; + } // Special Cases // p1, q1 and p2 are collinear and p2 lies on segment p1q1 |