org.andengine.util.algorithm.collision

Class BaseCollisionChecker

java.lang.Object

org.andengine.util.algorithm.collision.BaseCollisionChecker

Direct Known Subclasses:

ShapeCollisionChecker

public class BaseCollisionChecker
extends java.lang.Object

(c) 2010 Nicolas Gramlich (c) 2011 Zynga Inc.

Since:

11:50:19 - 11.03.2010

Constructor Summary

Constructors

Constructor and Description
BaseCollisionChecker()

Method Summary

Modifier and Type	Method and Description
static boolean	checkAxisAlignedRectangleCollision(float pLeftA, float pTopA, float pRightA, float pBottomA, float pLeftB, float pTopB, float pRightB, float pBottomB)
static boolean	checkAxisAlignedRectangleContains(float pLeft, float pTop, float pRight, float pBottom, float pX, float pY)
static int	relativeCCW(float pX1, float pY1, float pX2, float pY2, float pPX, float pPY) Returns an indicator of where the specified point (PX, PY) lies with respect to the line segment from (X1, Y1) to (X2, Y2).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BaseCollisionChecker

public BaseCollisionChecker()

Method Detail

checkAxisAlignedRectangleCollision

public static boolean checkAxisAlignedRectangleCollision(float pLeftA,
                                                         float pTopA,
                                                         float pRightA,
                                                         float pBottomA,
                                                         float pLeftB,
                                                         float pTopB,
                                                         float pRightB,
                                                         float pBottomB)

checkAxisAlignedRectangleContains

public static boolean checkAxisAlignedRectangleContains(float pLeft,
                                                        float pTop,
                                                        float pRight,
                                                        float pBottom,
                                                        float pX,
                                                        float pY)

relativeCCW

public static int relativeCCW(float pX1,
                              float pY1,
                              float pX2,
                              float pY2,
                              float pPX,
                              float pPY)

Returns an indicator of where the specified point (PX, PY) lies with respect to the line segment from (X1, Y1) to (X2, Y2). The return value can be either 1, -1, or 0 and indicates in which direction the specified line must pivot around its first endpoint, (X1, Y1), in order to point at the specified point (PX, PY).

A return value of 1 indicates that the line segment must turn in the direction that takes the positive X axis towards the negative Y axis. In the default coordinate system used by Java 2D, this direction is counterclockwise.

A return value of -1 indicates that the line segment must turn in the direction that takes the positive X axis towards the positive Y axis. In the default coordinate system, this direction is clockwise.

A return value of 0 indicates that the point lies exactly on the line segment. Note that an indicator value of 0 is rare and not useful for determining colinearity because of floating point rounding issues.

If the point is colinear with the line segment, but not between the endpoints, then the value will be -1 if the point lies "beyond (X1, Y1)" or 1 if the point lies "beyond (X2, Y2)".

Parameters:

pX1 - , Y1 the coordinates of the beginning of the specified line segment

pX2 - , Y2 the coordinates of the end of the specified line segment

pPX - , PY the coordinates of the specified point to be compared with the specified line segment

Returns:

an integer that indicates the position of the third specified coordinates with respect to the line segment formed by the first two specified coordinates.