/// <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 list of all the tiles intersecting bounds. The returned list is ordered for collision detection based on the
/// direction passed in so they can be processed in order.
/// </summary>
/// <returns>The colliding tiles.</returns>
/// <param name="bounds">Bounds.</param>
/// <param name="direction">Direction.</param>
void populateCollidingTiles( Rectangle bounds, Edge direction )
{
_collidingTiles.Clear();
var isHorizontal = direction.isHorizontal();
var primaryAxis = isHorizontal ? Axis.X : Axis.Y;
var oppositeAxis = primaryAxis == Axis.X ? Axis.Y : Axis.X;
var oppositeDirection = direction.oppositeEdge();
var firstPrimary = worldToTilePosition( bounds.getSide( oppositeDirection ), primaryAxis );
var lastPrimary = worldToTilePosition( bounds.getSide( direction ), primaryAxis );
var primaryIncr = direction.isMax() ? 1 : -1;
var min = worldToTilePosition( isHorizontal ? bounds.Top : bounds.Left, oppositeAxis );
var mid = worldToTilePosition( isHorizontal ? bounds.getCenter().Y : bounds.getCenter().X, oppositeAxis );
var max = worldToTilePosition( isHorizontal ? bounds.Bottom : bounds.Right, oppositeAxis );
var isPositive = mid - min < max - mid;
var secondaryIncr = isPositive ? 1 : -1;
var firstSecondary = isPositive ? min : max;
var lastSecondary = !isPositive ? min : max;
for( var primary = firstPrimary; primary != lastPrimary + primaryIncr; primary += primaryIncr )
{
for( var secondary = firstSecondary; secondary != lastSecondary + secondaryIncr; secondary += secondaryIncr )
{
var col = isHorizontal ? primary : secondary;
var row = !isHorizontal ? primary : secondary;
_collidingTiles.Add( collisionLayer.getTile( col, row ) );
#if DEBUG_MOVER
if( direction.isHorizontal() )
{
var pos = tiledMap.tileToWorldPosition( new Point( col, row ) );
_debugTiles.Add( new Rectangle( (int)pos.X, (int)pos.Y, 16, 16 ) );
}
#endif
}
}
}
/// <summary>
/// gets a list of all the tiles intersecting bounds. The returned list is ordered for collision detection based on the
/// direction passed in so they can be processed in order.
/// </summary>
/// <returns>The colliding tiles.</returns>
/// <param name="bounds">Bounds.</param>
/// <param name="direction">Direction.</param>
void populateCollidingTiles( Rectangle bounds, Edge direction )
{
_collidingTiles.Clear();
var isHorizontal = direction.isHorizontal();
var primaryAxis = isHorizontal ? Axis.X : Axis.Y;
var oppositeAxis = primaryAxis == Axis.X ? Axis.Y : Axis.X;
// if we are going up or left we subtract 1 from our opposite edge so that it doesnt get the column/row of tiles when we are against them
var oppositeDirection = direction.oppositeEdge();
var minSidePad = direction.isMin() ? -1 : 0;
var firstPrimary = worldToTilePosition( bounds.getSide( oppositeDirection ) + minSidePad, primaryAxis );
var lastPrimary = worldToTilePosition( bounds.getSide( direction ), primaryAxis );
var primaryIncr = direction.isMax() ? 1 : -1;
var min = worldToTilePosition( isHorizontal ? bounds.Top : bounds.Left, oppositeAxis );
var mid = worldToTilePosition( isHorizontal ? bounds.getCenter().Y : bounds.getCenter().X, oppositeAxis );
// same as above here. we subtract 1 to not grab an extra column/row of tiles which will mess up collisions
var max = worldToTilePosition( isHorizontal ? bounds.Bottom - 1 : bounds.Right - 1, oppositeAxis );
var isPositive = mid - min < max - mid;
var secondaryIncr = isPositive ? 1 : -1;
var firstSecondary = isPositive ? min : max;
var lastSecondary = !isPositive ? min : max;
for( var primary = firstPrimary; primary != lastPrimary + primaryIncr; primary += primaryIncr )
{
for( var secondary = firstSecondary; secondary != lastSecondary + secondaryIncr; secondary += secondaryIncr )
{
var col = isHorizontal ? primary : secondary;
var row = !isHorizontal ? primary : secondary;
_collidingTiles.Add( _collisionLayer.getTile( col, row ) );
}
}
}
