// Returns the largest move that this can make in the move direction, given another circle at offset
public override double[] moveTo(GameCircle other, double[] offset, double[] move)
{
GameCircle c1 = this;
GameCircle c2 = other;
double radius = c1.getRadius() + c2.getRadius();
double desiredLength = Math.Sqrt(move[0] * move[0] + move[1] * move[1]);
double distFromPath = Math.Abs(offset[0] * move[1] - offset[1] * move[0]) / desiredLength;
if ((distFromPath >= radius) || (offset[0] * move[0] + offset[1] * move[1] <= 0))
{
// if we get here then the circles never collide and so any move is okay
return(move); // return the same move to indicate that this move is okay
}
double distToClosestPoint = Math.Sqrt((offset[0] * offset[0] + offset[1] * offset[1]) - distFromPath * distFromPath);
double allowedLength = distToClosestPoint - Math.Sqrt(radius * radius - distFromPath * distFromPath);
if (allowedLength >= desiredLength)
{
// if we get here then the desired move is not long enough to collide
return(move);
}
double[] result = new double[2]; // create a new array to indicate that this move is different
result[0] = move[0] * allowedLength / desiredLength;
result[1] = move[1] * allowedLength / desiredLength;
return(result);
}
// Tells whether a GameCircle would intersect another at offset
public override bool intersects(GameCircle other, double[] offset)
{
double totalRadius = this.radius + other.radius;
if (offset[0] * offset[0] + offset[1] * offset[1] < totalRadius * totalRadius)
{
return(true);
}
else
{
return(false);
}
}
// Returns the maximum amount of distance that this can move in the move direction, given a rectangle at offset
public override double[] moveTo(GameRectangle other, double[] offset, double[] move)
{
GameCircle c = this;
GameRectangle r = other;
double[] mirroredMove = new double[move.Length];
double[] mirroredOffset = new double[move.Length];
int i;
// flip the coordinate system so that the offset is positive in all dimensions
for (i = 0; i < move.Length; i++)
{
if (offset[i] >= 0)
{
mirroredOffset[i] = offset[i];
mirroredMove[i] = move[i];
}
else
{
mirroredOffset[i] = -offset[i];
mirroredMove[i] = -move[i];
}
}
//System.Collections.Generic.List<double[]> intersections;
//double[] tempIntersection;
// figure out where it may intersect the left/right wall
double width = r.getWidth() / 2 + c.getRadius();
if (mirroredMove[0] > 0 && mirroredOffset[0] >= width)
{
// calculate where it will intersect this line
double[] allowedMove = new double[2];
allowedMove[0] = mirroredOffset[0] - width;
// check that it will go far enough to collide
if (allowedMove[0] < mirroredMove[0])
{
allowedMove[1] = allowedMove[0] * mirroredMove[1] / mirroredMove[0];
// make sure that it actually intersects the line segment and not just the line
if (Math.Abs(mirroredOffset[1] - allowedMove[1]) <= r.getHeight() / 2)
{
// reflect it back correctly and return
if (offset[0] < 0)
{
allowedMove[0] *= -1;
}
if (offset[1] < 0)
{
allowedMove[1] *= -1;
}
return(allowedMove);
}
}
}
double height = r.getHeight() / 2 + c.getRadius();
if (mirroredMove[1] > 0 && mirroredOffset[1] >= height)
{
// calculate where it will intersect this line
double[] allowedMove = new double[2];
allowedMove[1] = mirroredOffset[1] - height;
// check that it will go far enough to collide
if (allowedMove[1] < mirroredMove[1])
{
allowedMove[0] = allowedMove[1] * mirroredMove[0] / mirroredMove[1];
// make sure that it actually intersects the line segment and not just the line
if (Math.Abs(mirroredOffset[0] - allowedMove[0]) <= r.getWidth() / 2)
{
// reflect it back correctly and return
if (offset[0] < 0)
{
allowedMove[0] *= -1;
}
if (offset[1] < 0)
{
allowedMove[1] *= -1;
}
return(allowedMove);
}
}
}
// figure out where it may intersect the corner arc
double length = Math.Sqrt(move[0] * move[0] + move[1] * move[1]);
double signedWidth = r.getWidth() / 2;
double signedHeight = r.getHeight() / 2;
for (i = 0; i < 2; i++)
{
double lateralOffset = (mirroredOffset[0] - signedWidth) * mirroredMove[1] / length - (mirroredOffset[1] - signedHeight) * mirroredMove[0] / length;
// first check that the movement line will reach the arc
if (Math.Abs(lateralOffset) <= c.getRadius())
{
double forwardOffset = (mirroredOffset[0] - signedWidth) * mirroredMove[0] / length + (mirroredOffset[1] - signedHeight) * mirroredMove[1] / length;
// Next check that the movement line is facing the right direction
if (forwardOffset >= 0)
{
double collisionDist = forwardOffset - Math.Sqrt(c.getRadius() * c.getRadius() - lateralOffset * lateralOffset);
// Make sure that it is hitting the outside of the arc
if ((Math.Abs(mirroredOffset[0] - mirroredMove[0] * collisionDist / length) >= r.getWidth() / 2) &&
(Math.Abs(mirroredOffset[1] - mirroredMove[1] * collisionDist / length) >= r.getHeight() / 2))
{
// If we get here then it is, in fact, moving toward the corner of the rectangle from the outside. Now decide if it wants to move that far
// if it doesn't want to move that far, then it can just keep going
if (collisionDist >= length)
{
return(move);
}
else
{
// If we get here, it means is would collide with the arc and we need to shorten the length
double[] allowedMove = new double[2];
allowedMove[0] = move[0] * collisionDist / length;
allowedMove[1] = move[1] * collisionDist / length;
return(allowedMove);
}
}
}
}
// Now alter the coordinates to check the other corner, and repeat
if ((mirroredOffset[0] - signedWidth) * mirroredMove[0] >= (mirroredOffset[1] - signedHeight) * mirroredMove[1])
{
// switch vertically because we're closer to the left/right edge
signedHeight *= -1;
}
else
{
// switch vertically because we're closer to the left/right edge
signedWidth *= -1;
}
}
// If we get here, there are no collisions and so any move is fine
return(move);
}
// Tells whether this intersects a circle at offset
public override bool intersects(GameCircle other, double[] offset)
{
// This checker is symetric
return(other.intersects(this, offset));
}
// Returns the maximum amount of distance that this can move in the move direction, given a circle at offset
public override double[] moveTo(GameCircle other, double[] offset, double[] move)
{
// This collision checker happens to be symetric
double[] allowedMove = other.moveTo(this, offset, move);
return(allowedMove);
}
public virtual bool intersects(GameCircle other, double[] offset)
{
return(false);
}
public virtual double[] moveTo(GameCircle other, double[] offset, double[] move)
{
return(null);
}