From d73d4327d339764fccf57c04cc2d975cfdef4b3c Mon Sep 17 00:00:00 2001 From: Joshua Grams Date: Sat, 25 Mar 2006 20:57:18 +0000 Subject: [PATCH] correct bounce math? --- sprite.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/sprite.c b/sprite.c index abe9fb3..e63fd68 100644 --- a/sprite.c +++ b/sprite.c @@ -340,8 +340,8 @@ void bounce(Sprite *a, Sprite *b) { float x, y, n; - float va, vb; - float ma, mb, mr; + float va, vb, vc; + float ma, mb; // (x, y) is unit vector pointing from A's center to B's center. x = (b->x + b->w / 2) - (a->x + a->w / 2); @@ -352,10 +352,9 @@ bounce(Sprite *a, Sprite *b) va = max(x*a->dx + y*a->dy, 0); vb = min(x*b->dx + y*b->dy, 0); - // mass ratio ma = sprite_mass(a); mb = sprite_mass(b); - if(ma && mb) mr = mb/ma; else mr = 1; + vc = (va*ma + vb*mb) / (ma+mb); - a->dx += x*(mb*vb - ma*va)/ma; a->dy += y*(mb*vb - ma*va)/ma; - b->dx += x*(ma*va - mb*vb)/mb; b->dy += y*(ma*va - mb*vb)/mb; + a->dx += 2*x*(vc-va); a->dy += 2*y*(vc-va); + b->dx += 2*x*(vc-vb); b->dy += 2*y*(vc-vb); } -- 1.7.10.4