/// <summary>
/// Tests the tile for a collision. Returns via out the position in world space where the collision occured.
/// </summary>
/// <returns>The tile collision.</returns>
/// <param name="tile">Tile.</param>
/// <param name="edgeToTest">the opposite side of movement, the side the leading edge will collide with</param>
/// <param name="perpindicularPosition">Perpindicular position.</param>
/// <param name="leadingPosition">Leading position.</param>
/// <param name="shouldTestSlopes">Should test slopes.</param>
/// <param name="collisionResponse">Collision response.</param>
bool testTileCollision( TiledTile tile, Edge edgeToTest, int perpindicularPosition, int leadingPosition, bool shouldTestSlopes, out int collisionResponse )
{
collisionResponse = leadingPosition;
// one way platforms are only collideable from the top when the player is already above them
if( tile.isOneWayPlatform() )
{
// only the top edge of one way platforms are checked for collisions
if( edgeToTest != Edge.Top )
return false;
// our response should be the top of the platform
collisionResponse = tiledMap.tileToWorldPositionX( tile.y );
return _boxColliderBounds.Bottom <= collisionResponse;
}
var forceSlopedTileCheckAsWall = false;
// when moving horizontally the only time a slope is considered for collision testing is when its closest side is the tallest side
// and we were not intesecting the tile before moving.
// this prevents clipping through a tile when hitting its edge: -> |\
if( edgeToTest.isHorizontal() && tile.isSlope() && tile.getNearestEdge( leadingPosition ) == tile.getHighestSlopeEdge() )
{
var moveDir = edgeToTest.oppositeEdge();
var leadingPositionPreMovement = _boxColliderBounds.getSide( moveDir );
// we need the tile x position that is on the opposite side of our move direction. Moving right we want the left edge
var tileX = moveDir == Edge.Right ? tiledMap.tileToWorldPositionX( tile.x ) : tiledMap.tileToWorldPositionX( tile.x + 1 );
// using the edge before movement, we see if we were colliding before moving.
var wasCollidingBeforeMove = moveDir == Edge.Right ? leadingPositionPreMovement > tileX : leadingPositionPreMovement < tileX;
// if we were not colliding before moving we need to consider this tile for a collision check as if it were a wall tile
forceSlopedTileCheckAsWall = !wasCollidingBeforeMove;
}
if( forceSlopedTileCheckAsWall || !tile.isSlope() )
{
switch( edgeToTest )
{
case Edge.Top:
collisionResponse = tiledMap.tileToWorldPositionY( tile.y );
break;
case Edge.Bottom:
collisionResponse = tiledMap.tileToWorldPositionY( tile.y + 1 );
break;
case Edge.Left:
collisionResponse = tiledMap.tileToWorldPositionX( tile.x );
break;
case Edge.Right:
collisionResponse = tiledMap.tileToWorldPositionX( tile.x + 1 );
break;
}
return true;
}
if( shouldTestSlopes )
{
var tileWorldX = tiledMap.tileToWorldPositionX( tile.x );
var tileWorldY = tiledMap.tileToWorldPositionX( tile.y );
var slope = tile.getSlope();
var offset = tile.getSlopeOffset();
// calculate the point on the slope at perpindicularPosition
collisionResponse = (int)( edgeToTest.isVertical() ? slope * ( perpindicularPosition - tileWorldX ) + offset + tileWorldY : ( perpindicularPosition - tileWorldY - offset ) / slope + tileWorldX );
var isColliding = edgeToTest.isMax() ? leadingPosition <= collisionResponse : leadingPosition >= collisionResponse;
// this code ensures that we dont consider collisions on a slope while jumping up that dont intersect our collider.
// It also makes sure when testing the bottom edge that the leadingPosition is actually above the collisionResponse.
// HACK: It isn't totally perfect but it does the job
if( isColliding && edgeToTest == Edge.Bottom && leadingPosition <= collisionResponse )
isColliding = false;
return isColliding;
}
return false;
}
/// <summary>
/// gets a collision rect for the given side expanded to take into account motion
/// </summary>
/// <returns>The rect for side.</returns>
/// <param name="side">Side.</param>
/// <param name="motion">Motion.</param>
Rectangle collisionRectForSide( Edge side, int motion )
{
Rectangle bounds;
// for horizontal collision checks we use just a sliver for our bounds. Vertical gets the half rect so that it can properly push
// up when intersecting a slope which is ignored when moving horizontally.
if( side.isHorizontal() )
bounds = _boxColliderBounds.getRectEdgePortion( side );
else
bounds = _boxColliderBounds.getHalfRect( side );
// we contract horizontally for vertical movement and vertically for horizontal movement
if( side.isVertical() )
RectangleExt.contract( ref bounds, colliderHorizontalInset, 0 );
else
RectangleExt.contract( ref bounds, 0, colliderVerticalInset );
// finally expand the side in the direction of movement
RectangleExt.expandSide( ref bounds, side, motion );
return bounds;
}
/// <summary>
/// gets a collision rect for the given side expanded to take into account motion
/// </summary>
/// <returns>The rect for side.</returns>
/// <param name="side">Side.</param>
/// <param name="motion">Motion.</param>
Rectangle collisionRectForSide( Edge side, int motion )
{
var bounds = (Rectangle)_collider.bounds;
bounds = bounds.getHalfRect( side );
// we contract horizontally for vertical movement and vertically for horizontal movement
if( side.isVertical() )
RectangleExt.contract( ref bounds, colliderHorizontalInset, 0 );
else
RectangleExt.contract( ref bounds, 0, colliderVerticalInset );
// finally expand the side in the direction of movement
RectangleExt.expandSide( ref bounds, side, motion );
return bounds;
}
