// -------------------------- Kick ----------------------------------------
//
// applys a force to the ball in the direction of heading. Truncates
// the new velocity to make sure it doesn't exceed the max allowable.
// ------------------------------------------------------------------------
public void kick(Vector2D direction, double force) {
// ensure direction is normalized
Vector2D d = direction.cloneVec();
d.Normalize();
// calculate the acceleration
Vector2D acceleration = d.multiply(force).divide(mass);
// update the velocity
velocity.cloneVec(acceleration);
}
// ----------------------- TestCollisionWithWalls -------------------------
//
public void testCollisionWithWalls(List<Wall2D> walls) {
// test ball against each wall, find out which is closest
int idxClosest = -1;
// println ("Colision " +velocity)
Vector2D velNormal = Vec2DNormalize(velocity);
Vector2D intersectionPoint = new Vector2D();
Vector2D collisionPoint = new Vector2D();
double distToIntersection = Double.MAX_VALUE;
// iterate through each wall and calculate if the ball intersects.
// If it does then store the index into the closest intersecting wall
for (int w = 0; w < walls.size(); ++w) {
// assuming a collision if the ball continued on its current heading
// calculate the point on the ball that would hit the wall. This is
// simply the wall's normal(inversed) multiplied by the ball's radius
// and added to the balls center (its position)
Wall2D wallSegment = walls.get(w);
Vector2D thisCollisionPoint = getPos().minus(wallSegment.Normal().multiply(getBRadius()));
// calculate exactly where the collision point will hit the plane
if (Geometry2DFunctions.whereIsPoint(
thisCollisionPoint, wallSegment.From(), wallSegment.Normal())
== Geometry2DFunctions.SpanType.plane_backside) {
double distToWall =
distanceToRayPlaneIntersection(
thisCollisionPoint, wallSegment.Normal(), wallSegment.From(), wallSegment.Normal());
intersectionPoint = thisCollisionPoint.plus(wallSegment.Normal().multiply(distToWall));
} else {
double distToWall =
distanceToRayPlaneIntersection(
thisCollisionPoint, velNormal, wallSegment.From(), wallSegment.Normal());
intersectionPoint = thisCollisionPoint.plus(velNormal.multiply(distToWall));
}
// check to make sure the intersection point is actually on the line
// segment
boolean OnLineSegment = false;
Vector2D wallNormal = wallSegment.Normal().multiply(20.0);
if (LineIntersection2D(
wallSegment.From(),
wallSegment.To(),
thisCollisionPoint.minus(wallNormal),
thisCollisionPoint.plus(wallNormal))) {
OnLineSegment = true;
}
// Note, there is no test for collision with the end of a line segment
// now check to see if the collision point is within range of the
// velocity vector. [work in distance squared to avoid Math.sqrt] and if it
// is the closest hit found so far.
// If it is that means the ball will collide with the wall sometime
// between this time step and the next one.
double distSq = vec2DDistanceSq(thisCollisionPoint, intersectionPoint);
if ((distSq <= velocity.LengthSq()) && (distSq < distToIntersection) && OnLineSegment) {
distToIntersection = distSq;
idxClosest = w;
collisionPoint = intersectionPoint;
}
} // next wall
// to prevent having to calculate the exact time of collision we
// can just check if the velocity is opposite to the wall normal
// before reflecting it. This prevents the case where there is overshoot
// and the ball gets reflected back over the line before it has completely
// reentered the playing area.
if ((idxClosest >= 0) && velNormal.dot(walls.get(idxClosest).Normal()) < 0) {
velocity.Reflect(walls.get(idxClosest).Normal());
}
}
