public static bool CollideBoxBox(Box2D boxA, Vector2 velocityA, Box2D boxB, float interpenetrationCorrection,
out float collisionTime, out Vector2 collisionNormal, out Vector2 collisionEdge)
{
#if COLLIDE_VIA_3D_ON_X
Box3D boxA_3d = new Box3D(new Vector3(0, boxA.Min.X, boxA.Min.Y), new Vector3(1, boxA.Max.X, boxA.Max.Y));
Vector3 velocityA_3d = new Vector3(0, velocityA.X, velocityA.Y);
Box3D boxB_3d = new Box3D(new Vector3(0, boxB.Min.X, boxB.Min.Y), new Vector3(1, boxB.Max.X, boxB.Max.Y));
bool returnValue = Collision3D.CollideBoxBox(boxA_3d, velocityA_3d, boxB_3d, interpenetrationCorrection,
out collisionTime, out Vector3 collisionNormal_3d, out Vector3 collisionEdgeUp_3d, out Vector3 collisionEdgeSide_3d);
collisionNormal = new Vector2(collisionNormal_3d.Y, collisionNormal_3d.Z);
collisionEdge = new Vector2(collisionEdgeUp_3d.Y, collisionEdgeUp_3d.X);
return(returnValue);
#elif COLLIDE_VIA_3D_ON_Z
Box3D boxA_3d = new Box3D(new Vector3(boxA.Min.X, boxA.Min.Y, 0), new Vector3(boxA.Max.X, boxA.Max.Y, 1));
Vector3 velocityA_3d = new Vector3(velocityA.X, velocityA.Y, 0);
Box3D boxB_3d = new Box3D(new Vector3(boxB.Min.X, boxB.Min.Y, 0), new Vector3(boxB.Max.X, boxB.Max.Y, 1));
bool returnValue = Collision3D.CollideBoxBox(boxA_3d, velocityA_3d, boxB_3d, interpenetrationCorrection,
out collisionTime, out Vector3 collisionNormal_3d, out Vector3 collisionEdgeUp_3d, out Vector3 collisionEdgeSide_3d);
collisionNormal = new Vector2(collisionNormal_3d.X, collisionNormal_3d.Y);
collisionEdge = new Vector2(collisionEdgeUp_3d.X, collisionEdgeUp_3d.Y);
return(returnValue);
#else
Box2D expandedBoxB = boxB.ExpandBy(boxA);
Vector2 boxACenter = boxA.Center;
Vector2 velocityAInverse = new Vector2(1.0f / velocityA.X, 1.0f / velocityA.Y);
float timeX1 = (expandedBoxB.Min.X - boxACenter.X) * velocityAInverse.X;
float timeX2 = (expandedBoxB.Max.X - boxACenter.X) * velocityAInverse.X;
float timeY1 = (expandedBoxB.Min.Y - boxACenter.Y) * velocityAInverse.Y;
float timeY2 = (expandedBoxB.Max.Y - boxACenter.Y) * velocityAInverse.Y;
float firstCollideTimeX = Math.Min(timeX1, timeX2);
float lastCollideTimeX = Math.Max(timeX1, timeX2);
float firstCollideTimeY = Math.Min(timeY1, timeY2);
float lastCollideTimeY = Math.Max(timeY1, timeY2);
float firstCollideTime = Math.Max(firstCollideTimeX, firstCollideTimeY);
float lastCollideTime = Math.Min(lastCollideTimeX, lastCollideTimeY);
collisionTime = firstCollideTime;
if (firstCollideTime == timeX1)
{
collisionNormal = -Vector2.UnitX;
collisionEdge = Vector2.UnitY;
}
else if (firstCollideTime == timeX2)
{
collisionNormal = Vector2.UnitX;
collisionEdge = Vector2.UnitY;
}
else if (firstCollideTime == timeY1)
{
collisionNormal = -Vector2.UnitY;
collisionEdge = Vector2.UnitX;
}
else
{
collisionNormal = Vector2.UnitY;
collisionEdge = Vector2.UnitX;
}
if (firstCollideTime < 0 && firstCollideTime > -interpenetrationCorrection)
{
// This accounts for floating point imprecision where a box might be moved to meet another box
// but now actually slightly interpenetrates the box because the true position cannot be represented.
// If boxes are slightly interpenetrating this treats them as if they are just touching.
firstCollideTime = 0;
}
return(lastCollideTime > Math.Max(firstCollideTime, 0.0f) && firstCollideTime >= 0 && firstCollideTime < 1.0f);
#endif
}
public static bool CollideBoxBox(Box2D boxA, Vector2 velocityA, Box2D boxB, float interpenetrationCorrection, out float collisionTime)
{
return(Collision2D.CollideBoxBox(boxA, velocityA, boxB, interpenetrationCorrection,
out collisionTime, out _, out _));
}