diff options
Diffstat (limited to 'collision.cpp')
| -rw-r--r-- | collision.cpp | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/collision.cpp b/collision.cpp index 7e69ba7..a72bb7d 100644 --- a/collision.cpp +++ b/collision.cpp @@ -1,5 +1,8 @@ #include "balls.h" +#define EPSILON 1e-7 + /* account for floating-point error when testing for collision */ + static void setPosition(Ball *b1, Ball *b2); static Vector reaction(Ball b1, Ball b2); static double clamp(double v, double lo, double hi); @@ -8,16 +11,17 @@ static double max(double a, double b); int isCollision(Point p1, double r1, Point p2, double r2) { - double dx, dy; + double dx, dy, rhs; dx = p1.x - p2.x; dy = p1.y - p2.y; - return (dx*dx + dy*dy) <= (r1+r2)*(r1+r2); + rhs = r1 + r2 + EPSILON; + return (dx*dx + dy*dy) <= rhs*rhs; } void collideWall(Ball *b, Rectangle wall) { - wall = insetRect(wall, b->r); + wall = insetRect(wall, b->r + EPSILON); if (b->p.x < wall.min.x || b->p.x > wall.max.x) { b->p.x = clamp(b->p.x, wall.min.x, wall.max.x); @@ -52,8 +56,8 @@ setPosition(Ball *b1, Ball *b2) { mid = ptDivS(addPt(b1->p, b2->p), 2); n = unitNorm(VecPt(b1->p, b2->p)); - b1->p = ptSubVec(mid, vecMulS(n, b1->r)); - b2->p = ptAddVec(mid, vecMulS(n, b2->r)); + b1->p = ptSubVec(mid, vecMulS(n, b1->r + EPSILON)); + b2->p = ptAddVec(mid, vecMulS(n, b2->r + EPSILON)); } /* return the velocity of b1 after colliding with b2 */ |