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improved performance by always reusing collision objects

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liabru 2014-03-17 17:18:47 +00:00
parent 0add2f00c9
commit 4631768d6f
1 changed files with 23 additions and 10 deletions
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33
src/collision/SAT.js
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@ -27,20 +27,26 @@ var SAT = {};
canReusePrevCol = false; canReusePrevCol = false;
if (prevCol) { if (prevCol) {
var motion = bodyA.speed * bodyA.speed + bodyA.angularSpeed * bodyA.angularSpeed; // estimate total motion
motion += bodyB.speed * bodyB.speed + bodyB.angularSpeed * bodyB.angularSpeed; var motion = bodyA.speed * bodyA.speed + bodyA.angularSpeed * bodyA.angularSpeed
+ bodyB.speed * bodyB.speed + bodyB.angularSpeed * bodyB.angularSpeed;
// can reuse if collision was resting // we may be able to (partially) reuse collision result
// but only safe if collision was resting
canReusePrevCol = prevCol && prevCol.collided && motion < 0.2; canReusePrevCol = prevCol && prevCol.collided && motion < 0.2;
// reuse collision object
collision = prevCol;
} else {
collision = { collided: false, bodyA: bodyA, bodyB: bodyB };
} }
if (prevCol && canReusePrevCol) { if (prevCol && canReusePrevCol) {
// if we can reuse the collision result
// only need to test the previously found axis // we only need to test the previously found axis
var axes = [prevCol.bodyA.axes[prevCol.axisNumber]]; var axes = [prevCol.bodyA.axes[prevCol.axisNumber]];
minOverlap = _overlapAxes(prevCol.bodyA.vertices, prevCol.bodyB.vertices, axes);
collision = previousCollision; minOverlap = _overlapAxes(prevCol.bodyA.vertices, prevCol.bodyB.vertices, axes);
collision.reused = true; collision.reused = true;
if (minOverlap.overlap <= 0) { if (minOverlap.overlap <= 0) {
@ -48,26 +54,33 @@ var SAT = {};
return collision; return collision;
} }
} else { } else {
collision = { collided: false, bodyA: bodyA, bodyB: bodyB }; // if we can't reuse a result, perform a full SAT test
overlapAB = _overlapAxes(bodyA.vertices, bodyB.vertices, bodyA.axes); overlapAB = _overlapAxes(bodyA.vertices, bodyB.vertices, bodyA.axes);
if (overlapAB.overlap <= 0) if (overlapAB.overlap <= 0) {
collision.collided = false;
return collision; return collision;
}
overlapBA = _overlapAxes(bodyB.vertices, bodyA.vertices, bodyB.axes); overlapBA = _overlapAxes(bodyB.vertices, bodyA.vertices, bodyB.axes);
if (overlapBA.overlap <= 0) if (overlapBA.overlap <= 0) {
collision.collided = false;
return collision; return collision;
}
if (overlapAB.overlap < overlapBA.overlap) { if (overlapAB.overlap < overlapBA.overlap) {
minOverlap = overlapAB; minOverlap = overlapAB;
collision.bodyA = bodyA;
collision.bodyB = bodyB;
} else { } else {
minOverlap = overlapBA; minOverlap = overlapBA;
collision.bodyA = bodyB; collision.bodyA = bodyB;
collision.bodyB = bodyA; collision.bodyB = bodyA;
} }
// important for reuse later
collision.axisNumber = minOverlap.axisNumber; collision.axisNumber = minOverlap.axisNumber;
} }