?? angle.java
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/**
* $Id:Angle.java $
*
* Copyright 2004 ~ 2005 JingFei International Cooperation LTD. All rights reserved. *
*/
package com.jfimagine.jfgraph.geom;
/**
* Angle class. A class used to encapsulate angle processes.
*
* @author CookieMaker
*
* @version $Revision: 1.00 $
*/
public class Angle{
/**
* PI for the angle of 180 degrees.
*/
public static final double PI =3.1415926;
/**
* An angle from 0 to 2*PI.
*/
private double m_angle =0;
/**
* Get the value of angle.
*
* @return The angle value.
*
*/
public double getAngle(){
return m_angle;
}
/**
* Set angle value.
* We should force an angle between 0 ~ 2*PI here.
*
* @param val A new rotate angle.
*
*/
public void setAngle(double val){
m_angle =getValidAngle(val);
}
/**
* Set angle value.
* We should force an angle between 0 ~ 2*PI here.
*
* @param val A new rotate angle.
* @return a new angle between 0 ~ 2PI
*
*/
public static double getValidAngle(double val){
while (val<0)
val +=2 * PI;
while (val>= 2 * PI)
val -=2 * PI;
return val;
}
/**
* Get the angle between the line from base point to target point1
* and the line from base point to target point2
*
* @param basePoint A base point.
* @param targetPoint1 The target point1.
* @param targetPoint2 The target point2.
* @return The angle.
*
*/
public static double getAngle(JFPoint basePoint, JFPoint targetPoint1, JFPoint targetPoint2){
return getAngle(basePoint,targetPoint1,targetPoint2,false);
}
/**
* Get the angle between the line from base point to target point1
* and the line from base point to target point2
*
* @param basePoint A base point.
* @param targetPoint1 The target point1.
* @param targetPoint2 The target point2.
* @param hasDirection Indicate that if this angle will follow the direction that targetPoint2 is under
* clockwise side of targetPoint1 according to basePoint, if so, the angle is a plus value, otherwise negative.
* @return The angle.
*
*/
public static double getAngle(JFPoint basePoint, JFPoint targetPoint1, JFPoint targetPoint2, boolean hasDirection){
if (basePoint==null || targetPoint1==null || targetPoint2==null)
return 0;
else{
return getAngle(basePoint.getX(),basePoint.getY(),
targetPoint1.getX(),targetPoint1.getY(),
targetPoint2.getX(), targetPoint2.getY(),hasDirection);
}
}
/**
* Get the angle between the line from base point to target point1
* and the line from base point to target point2
*
* @param basePointX, basePointY A base point.
* @param targetPoint1X, targetPoint1Y The target point1.
* @param targetPoint2X, targetPoint2Y The target point2.
* @return The angle, this angle will always less or equal than PI.
*
*/
public static double getAngle(double basePointX, double basePointY, double targetPoint1X, double targetPoint1Y, double targetPoint2X, double targetPoint2Y){
return getAngle(basePointX,basePointY,targetPoint1X,targetPoint1Y,targetPoint2X,targetPoint2Y,false);
}
/**
* Get the angle between the line from base point to target point1
* and the line from base point to target point2
*
* @param basePointX, basePointY A base point.
* @param targetPoint1X, targetPoint1Y The target point1.
* @param targetPoint2X, targetPoint2Y The target point2.
* @param hasDirection Indicate that if this angle will follow the direction that targetPoint2 is under
* clockwise side of targetPoint1 according to basePoint, if so, the angle is a plus value, otherwise negative.
* @return The angle, Math.abs(this angle) will always less or equal than PI.
*
*/
public static double getAngle(double basePointX, double basePointY, double targetPoint1X, double targetPoint1Y, double targetPoint2X, double targetPoint2Y, boolean hasDirection){
double angle1 =getAngle(basePointX, basePointY,targetPoint1X,targetPoint1Y);
double angle2 =getAngle(basePointX, basePointY,targetPoint2X,targetPoint2Y);
double result =Math.abs(angle2-angle1);
if (result>PI)
result =2 * PI - result;
if (!JFVector.underClockwiseSide(targetPoint2X,targetPoint2Y,basePointX,basePointY,
targetPoint1X,targetPoint1Y,basePointX,basePointY)){
result =-result;
}
return result;
}
/**
* Get the angle between the line from base point to target point
* and the horizontal line(from left to right).
*
* @param basePoint A base point.
* @param targetPoint The target point.
* @return The angle.
*
*/
public static double getAngle(JFPoint basePoint, JFPoint targetPoint){
return getAngle(basePoint,targetPoint,true);
}
/**
* Get the angle between the line from base point to target point
* and the horizontal line(from left to right).
*
* @param baseX, baseY Coordinates of the base point.
* @param targetX, targetY Coordinates of the target point.
* @return The angle.
*
*/
public static double getAngle(double baseX, double baseY,double targetX,double targetY){
return getAngle(baseX,baseY,targetX,targetY,true);
}
/**
* Get the angle between the line from base point to target point
* and the horizontal line(from left to right).
*
* @param basePoint A base point.
* @param targetPoint The target point.
* @param counterClockwiseAngle We treat the return angle is under a counter-clockwise quadrant system.
* @return The angle.
*
*/
public static double getAngle(JFPoint basePoint, JFPoint targetPoint, boolean counterClockwiseAngle){
return getAngle(basePoint.getX(),basePoint.getY(),targetPoint.getX(),targetPoint.getY(),counterClockwiseAngle);
}
/**
* Get the angle between the line from base point to target point
* and the horizontal line(from left to right).
*
* @param baseX, baseY Coordinates of the base point.
* @param targetX, targetY Coordinates of the target point.
* @param counterClockwiseAngle We treat the return angle is under a counter-clockwise quadrant system.
* @return The angle.
*
*/
public static double getAngle(double baseX, double baseY,double targetX,double targetY, boolean counterClockwiseAngle){
double angle=0;
if (baseX==targetX && baseY==targetY)
return 0;
//vertical line from basePoint to targetPoint
if ((float)baseX==(float)targetX){
if (counterClockwiseAngle){
if (baseY>targetY)
angle = PI/2;
else
angle = -1 * PI/2;
}else{
if (baseY<=targetY)
angle = PI/2;
else
angle = -1 * PI/2;
}
//horizontal line from basePoint to targetPoint
}else if ((float)baseY==(float)targetY){
if (baseX>targetX)
angle =PI;
else
angle =0;
}else{
double slope =(targetY-baseY)/(targetX-baseX);
angle =Math.atan(slope);
if (counterClockwiseAngle){
//for a counter clockwise quadrant system, we will adjust the angle to an ACTUAL slople in a counter-clockwise quadrant system.
if (slope>0){
//the angle will always under the first/third quadrant.
if (targetX < baseX){
angle = Angle.PI - angle;
}else{
angle = -1 * angle;
}
}else{
//the angle will always under the second/fourth quadrant.
if (targetX < baseX){
angle = Angle. PI + (Angle.PI * 2 -angle);
}else{
angle = -1 * angle;
}
}
}else{
//for a clockwise quadrant system, we will also adjust the angle.
if (slope>0){
//the angle will always under the first/third quadrant.
if (targetX < baseX){
angle = Angle.PI + angle;
}else{
angle = angle;
}
}else{
//the angle will always under the second/fourth quadrant.
if (targetX < baseX){
angle = Angle. PI - Math.abs(angle);
}else{
angle = angle;
}
}
}
}
return getValidAngle(angle);
}
/**
* Calculate a new slope after rotating by an angle.
*
* @param slope original slope of a line.
*
* @param angle new radian angle that rotated.
*
* @return A new slope.
*
*/
public static double newSlopeByAddingAngle(double slope,double angle){
double newSlope =0;
//force angle to 0 ~ 2PI
angle =getValidAngle(angle);
if ((float)angle==(float)PI/2 ||(float)angle==(float)PI * 3/2){
newSlope =GeomConst.LARGE_VALUE;
}else{
newSlope =Math.tan(angle);
}
return newSlopeByAddingSlope(slope,newSlope);
}
/**
* Calculate a new slope by append a new slope that rotated by a new angle.
*
* @param slope original slope of a line.
*
* @param newSlope a new slope appended.
*
* @return A new slope.
*
*/
public static double newSlopeByAddingSlope(double slope,double newSlope){
if (slope==0){
return newSlope;
}else if (slope==GeomConst.LARGE_VALUE){
if (newSlope==0)
return GeomConst.LARGE_VALUE;
else if (newSlope==GeomConst.LARGE_VALUE)
return 0;
else
return -1/newSlope;
}else if (newSlope==0){
return slope;
}else if (newSlope==GeomConst.LARGE_VALUE){
return -1/slope;
}else{
if ((float)slope==(float)1/newSlope)
return GeomConst.LARGE_VALUE;
else
//tan(alpha+beta)=(tan(alpha)+tan(beta))/(1-tan(alpha)*tan(beta))
return (slope+newSlope)/(1-slope*newSlope);
}
}
/**
* Add a new angle value to existance angle.
*
* @param angle A new angle value to be added.
*
*/
public void addAngle(double angle){
setAngle(m_angle + angle);
}
/**
* Constructor for Angle.
* Default to 0 for x and y coordinates.
*
*/
public Angle(){
m_angle =0;
}
/**
* Constructor for Angle.
*
* @param rect A rectangle object.
*
*/
public Angle(Angle angle){
if (angle!=null){
m_angle =angle.getAngle();
}
}
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