/// <summary>
/// Return a position that is both on the line and in the polygon.
/// </summary>
/// <param name="testProjectile"></param>
/// <param name="part"></param>
/// <returns></returns>
internal static CCPoint CollisionPosLinePoly(CollisionTypeLine cTypeLine, ICollidible polyCollidible)
{
// for performance reasons first check the bounding box (skip for now because we assume a collision is present
if (CollideBoundingBoxLine(polyCollidible, cTypeLine))
{
// transform the polygon to match the positioning, rotation and scale of the node
Polygon transformedPolygon = ((Polygon)((CollisionTypePolygon)polyCollidible.CollisionType).collisionPolygon.Clone());
transformedPolygon.TransformAccordingToGameObject(polyCollidible);
// first check if the polygon contains some of the two line points
if (transformedPolygon.ContainsPoint(cTypeLine.StartPoint))
{
return(cTypeLine.StartPoint);
}
else if (transformedPolygon.ContainsPoint(cTypeLine.EndPoint))
{
return(cTypeLine.EndPoint);
}
// solve exactly: check for line intersections
var polyPoints = transformedPolygon.Points;
int i, j;
for (i = 0, j = polyPoints.Length - 1; i < polyPoints.Length; j = i++)
{
if (CCPoint.SegmentIntersect(cTypeLine.StartPoint, cTypeLine.EndPoint, polyPoints[i], polyPoints[j]))
{
return(CCPoint.IntersectPoint(cTypeLine.StartPoint, cTypeLine.EndPoint, polyPoints[i], polyPoints[j]));
}
}
}
return(CCPoint.Zero);
}
internal static bool CollideBoundingBoxLine(ICollidible boxCollidible, CollisionTypeLine cTypeLine)
{
CCRect box = ((CCNode)boxCollidible).BoundingBoxTransformedToWorld;
float sx = cTypeLine.StartPoint.X;
float sy = cTypeLine.StartPoint.Y;
float ex = cTypeLine.EndPoint.X;
float ey = cTypeLine.EndPoint.Y;
// for performance first check whether both points of the line are outside and on one side of the box
if ((sx < box.MinX && ex < box.MinX) ||
(sx > box.MaxX && ex > box.MaxX) ||
(sy < box.MinY && ey < box.MinY) ||
(sy > box.MaxY && ey > box.MaxY))
{
return(false);
}
// check whether the start or end point is contained in the box
if (box.ContainsPoint(cTypeLine.StartPoint) || box.ContainsPoint(cTypeLine.EndPoint))
{
return(true);
}
// check for intersections of the line and the box boundaries
CCPoint[] boxPoints = Constants.CCRectPoints(box);
for (int i = 0; i < 3; i++)
{
if (CCPoint.SegmentIntersect(cTypeLine.StartPoint, cTypeLine.EndPoint, boxPoints[i], boxPoints[i + 1]))
{
return(true);
}
}
return(false);
}
/// <summary>
/// Check whether a bullet shot now would hit any parts of the TargetAircraft (if the TargetAircraft wouldn't move).
/// </summary>
/// <param name="partsInRange"></param>
/// <returns>whether the bullet would hit</returns>
internal bool WouldHit()
{
Constants.CCDegreesToDxDy(MyPart.TotalRotation, out float dx, out float dy);
CollisionTypeLine cTypeReachLine = new CollisionTypeLine(MyPart.PositionWorldspace, MyPart.PositionWorldspace + new CCPoint(dx * Reach, dy * Reach));
foreach (Part part in TargetAircraft.TotalParts)
{
if (Collisions.CollidePolygonLine(part, ((CollisionTypePolygon)part.CollisionType), cTypeReachLine))
return true;
}
return false;
}
private void Init()
{
CollisionType = new CollisionTypeLine(CCPoint.Zero, CCPoint.Zero);
}
internal static bool CollidePolygonLine(ICollidible polyCollidible, CollisionTypePolygon cTypePoly, CollisionTypeLine cTypeLine)
{
// for performance reasons first check the bounding box
if (CollideBoundingBoxLine(polyCollidible, cTypeLine))
{
// transform the polygon to match the positioning, rotation and scale of the node
Polygon transformedPolygon = ((Polygon)cTypePoly.collisionPolygon.Clone());
transformedPolygon.TransformAccordingToGameObject(polyCollidible);
// first check if the polygon contains some of the two line points
if (transformedPolygon.ContainsPoint(cTypeLine.StartPoint) || transformedPolygon.ContainsPoint(cTypeLine.EndPoint))
{
return(true);
}
// solve exactly: check for line intersections
var polyPoints = transformedPolygon.Points;
int i, j;
for (i = 0, j = polyPoints.Length - 1; i < polyPoints.Length; j = i++)
{
if (CCPoint.SegmentIntersect(cTypeLine.StartPoint, cTypeLine.EndPoint, polyPoints[i], polyPoints[j]))
{
return(true);
}
}
}
return(false);
}
internal static bool CollideCircleLine(ICollidible circleCollidible1, CollisionTypeCircle cTypeCircle1, CollisionTypeLine cTypeLine)
{
// calculate the length of the perpendicular line from the line to the center of the circle
CCPoint vectorPerpToLine = CCPoint.PerpendicularCCW((cTypeLine.EndPoint - cTypeLine.StartPoint));
CCPoint vectorLineStartToCircle = ((CCNode)circleCollidible1).PositionWorldspace - cTypeLine.StartPoint;
float perpLength = (float)Math.Abs(CCPoint.Dot(vectorPerpToLine, vectorLineStartToCircle) / vectorPerpToLine.Length);
return(perpLength <= CorrectRadius(circleCollidible1, cTypeCircle1));
}
internal static bool CollidePositionLine(ICollidible posCollidible, CollisionTypeLine cTypeLine)
{
CCPoint pos = ((CCNode)posCollidible).PositionWorldspace;
return(pos.Equals(cTypeLine.StartPoint) || pos.Equals(cTypeLine.EndPoint));
}