I posted this on the tail of the other thread I started, but it didn''t seem to get much response so now I''m hoping maybe someone will be kind enough to help me sort out this little problem I''m having. Having gone over and over and over and over my code, I have come to the conclusion that the problem must lie in my 2d line intersection code as it''s the only part of the code that I don''t understand 100%
Basically, I use two boxes for the collision boundaries of the player object. In the picture below, the white lines represent the collision shapes and the red lines indicate where the collisions actually occur.
As you can see, the upper left corner is screwed. The collisions are occuring too far out
So here''s my line intersection detection code:
bool ACollision::LineIntersect(float ax, float ay, float bx, float by,
float cx, float cy, float dx, float dy)
{
// line intersection test
float s = (cy - dy) * (bx - ax) - (cx - dx) * (by - ay);
if (s == 0)
{
// Lines don''t intersect
return false;
}
s = ((cy - ay) * (bx - ax) - (cx - ax) * (by - ay)) / s;
if (s < 0 || s > 1)
{
// Lines don''t intersect
return false;
}
return true;
}
The two lines run from (ax,ay) to (bx,by) and from (cx,cy) to (dx,dy).
Any idea where the problem might lie? I don''t fully understand how those two tests can detect all the possible line intersections, but that''s what was posted in another thread about 2d line intersection and was said to have been tested and worked.
