private static Boolean CircCirc(CollisionCircle comp1, CollisionCircle comp2)
{
double rad1 = comp1.Radius;
double rad2 = comp2.Radius;
double rad1Squared = rad1 * rad1;
double rad2Squared = rad2 * rad2;
double distanceSquared = (comp1.Center - comp2.Center).LengthSquared;
if (distanceSquared >= rad1Squared + rad2Squared)
{
return false;
}
return true;
}
private static Boolean RectCirc(CollisionRectangle rectangle, CollisionCircle circle)
{
// Transform rectangle corner coordinates and circle center to be axis-aligned
Matrix rotationMatrix = new Matrix();
rotationMatrix.Set2DRotate(-1 * rectangle.Rotation);
Vector rotatedTopLeft = rectangle.TopLeft * rotationMatrix;
Vector rotatedTopRight = rectangle.TopRight * rotationMatrix;
Vector rotatedBottomLeft = rectangle.BottomLeft * rotationMatrix;
Vector rotatedBottomRight = rectangle.BottomRight * rotationMatrix;
Vector rotatedCircleCenter = circle.Center * rotationMatrix;
double circRadius = circle.Radius;
Vector rotatedRectangleCenter = rotatedTopLeft + (rotatedBottomRight - rotatedTopLeft).Multiply(0.5);
double rectPercent = rectangle.CollisionPercent;
// Use of doubles and matrix operations can cause very very small discrepencies that should be ignored
if (Math.Abs(rotatedTopLeft.Y - rotatedTopRight.Y) > 0.00000001)
{
throw new Exception("Coordinate transform failed in CollisionDetector.RectCirc. TopLeft is " + rotatedTopLeft + " and TopRight is "+ rotatedTopRight);
}
bool isCircCenterOutsideRect = true;
double rectHalfWidth = 0.5 * Math.Abs(rotatedTopRight.X - rotatedTopLeft.X) * rectPercent;
double halfWidthPlusRadius = rectHalfWidth + circRadius;
double xSeparation = Math.Abs(rotatedCircleCenter.X - rotatedRectangleCenter.X);
if (xSeparation >= halfWidthPlusRadius) { return false; }
if (xSeparation < rectHalfWidth) { isCircCenterOutsideRect = false; }
double rectHalfHeight = 0.5 * Math.Abs(rotatedTopRight.Y - rotatedBottomRight.Y) * rectPercent;
double halfHeightPlusRadius = rectHalfWidth + circRadius;
double ySeparation = Math.Abs(rotatedCircleCenter.Y - rotatedRectangleCenter.Y);
if (ySeparation >= halfHeightPlusRadius) { return false; }
if (ySeparation < rectHalfHeight) { isCircCenterOutsideRect = false; }
if (!isCircCenterOutsideRect) { return true; }
// Check for literal corner cases
Vector closestCorner;
if (rotatedCircleCenter.X > rotatedRectangleCenter.X && rotatedCircleCenter.Y > rotatedRectangleCenter.Y) { closestCorner = rotatedTopRight; }
else if (rotatedCircleCenter.X > rotatedRectangleCenter.X && rotatedCircleCenter.Y <= rotatedRectangleCenter.Y) { closestCorner = rotatedBottomRight; }
else if (rotatedCircleCenter.Y > rotatedRectangleCenter.Y) { closestCorner = rotatedTopLeft; }
else { closestCorner = rotatedBottomLeft; }
if ((closestCorner - rotatedCircleCenter).LengthSquared > circRadius * circRadius) { return false; }
return true;
}
