/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS"
* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language
* governing permissions and limitations under the License.
******************************************************************************/
package com.badlogic.gdx.math;
import java.io.Serializable;
import com.badlogic.gdx.utils.NumberUtils;
/** A convenient 2D circle class.
* @author mzechner */
public class Circle implements Serializable, Shape2D {
public float x, y;
public float radius;
/** Constructs a new circle with all values set to zero */
public Circle () {
}
/** Constructs a new circle with the given X and Y coordinates and the given radius.
*
* @param x X coordinate
* @param y Y coordinate
* @param radius The radius of the circle */
public Circle (float x, float y, float radius) {
this.x = x;
this.y = y;
this.radius = radius;
}
/** Constructs a new circle using a given {@link Vector2} that contains the desired X and Y coordinates, and a given radius.
*
* @param position The position {@link Vector2}.
* @param radius The radius */
public Circle (Vector2 position, float radius) {
this.x = position.x;
this.y = position.y;
this.radius = radius;
}
/** Copy constructor
*
* @param circle The circle to construct a copy of. */
public Circle (Circle circle) {
this.x = circle.x;
this.y = circle.y;
this.radius = circle.radius;
}
/** Creates a new {@link Circle} in terms of its center and a point on its edge.
*
* @param center The center of the new circle
* @param edge Any point on the edge of the given circle */
public Circle (Vector2 center, Vector2 edge) {
this.x = center.x;
this.y = center.y;
this.radius = Vector2.len(center.x - edge.x, center.y - edge.y);
}
/** Sets a new location and radius for this circle.
*
* @param x X coordinate
* @param y Y coordinate
* @param radius Circle radius */
public void set (float x, float y, float radius) {
this.x = x;
this.y = y;
this.radius = radius;
}
/** Sets a new location and radius for this circle.
*
* @param position Position {@link Vector2} for this circle.
* @param radius Circle radius */
public void set (Vector2 position, float radius) {
this.x = position.x;
this.y = position.y;
this.radius = radius;
}
/** Sets a new location and radius for this circle, based upon another circle.
*
* @param circle The circle to copy the position and radius of. */
public void set (Circle circle) {
this.x = circle.x;
this.y = circle.y;
this.radius = circle.radius;
}
/** Sets this {@link Circle}'s values in terms of its center and a point on its edge.
*
* @param center The new center of the circle
* @param edge Any point on the edge of the given circle */
public void set (Vector2 center, Vector2 edge) {
this.x = center.x;
this.y = center.y;
this.radius = Vector2.len(center.x - edge.x, center.y - edge.y);
}
/** Sets the x and y-coordinates of circle center from vector
* @param position The position vector */
public void setPosition (Vector2 position) {
this.x = position.x;
this.y = position.y;
}
/** Sets the x and y-coordinates of circle center
* @param x The x-coordinate
* @param y The y-coordinate */
public void setPosition (float x, float y) {
this.x = x;
this.y = y;
}
/** Sets the x-coordinate of circle center
* @param x The x-coordinate */
public void setX (float x) {
this.x = x;
}
/** Sets the y-coordinate of circle center
* @param y The y-coordinate */
public void setY (float y) {
this.y = y;
}
/** Sets the radius of circle
* @param radius The radius */
public void setRadius (float radius) {
this.radius = radius;
}
/** Checks whether or not this circle contains a given point.
*
* @param x X coordinate
* @param y Y coordinate
*
* @return true if this circle contains the given point. */
public boolean contains (float x, float y) {
x = this.x - x;
y = this.y - y;
return x * x + y * y <= radius * radius;
}
/** Checks whether or not this circle contains a given point.
*
* @param point The {@link Vector2} that contains the point coordinates.
*
* @return true if this circle contains this point; false otherwise. */
public boolean contains (Vector2 point) {
float dx = x - point.x;
float dy = y - point.y;
return dx * dx + dy * dy <= radius * radius;
}
/** @param c the other {@link Circle}
* @return whether this circle contains the other circle. */
public boolean contains (Circle c) {
final float radiusDiff = radius - c.radius;
if (radiusDiff < 0f) return false; // Can't contain bigger circle
final float dx = x - c.x;
final float dy = y - c.y;
final float dst = dx * dx + dy * dy;
final float radiusSum = radius + c.radius;
return (!(radiusDiff * radiusDiff < dst) && (dst < radiusSum * radiusSum));
}
/** @param c the other {@link Circle}
* @return whether this circle overlaps the other circle. */
public boolean overlaps (Circle c) {
float dx = x - c.x;
float dy = y - c.y;
float distance = dx * dx + dy * dy;
float radiusSum = radius + c.radius;
return distance < radiusSum * radiusSum;
}
/** Returns a {@link String} representation of this {@link Circle} of the form {@code x,y,radius}. */
@Override
public String toString () {
return x + "," + y + "," + radius;
}
/** @return The circumference of this circle (as 2 * {@link MathUtils#PI2}) * {@code radius} */
public float circumference () {
return this.radius * MathUtils.PI2;
}
/** @return The area of this circle (as {@link MathUtils#PI} * radius * radius). */
public float area () {
return this.radius * this.radius * MathUtils.PI;
}
@Override
public boolean equals (Object o) {
if (o == this) return true;
if (o == null || o.getClass() != this.getClass()) return false;
Circle c = (Circle)o;
return this.x == c.x && this.y == c.y && this.radius == c.radius;
}
@Override
public int hashCode () {
final int prime = 41;
int result = 1;
result = prime * result + NumberUtils.floatToRawIntBits(radius);
result = prime * result + NumberUtils.floatToRawIntBits(x);
result = prime * result + NumberUtils.floatToRawIntBits(y);
return result;
}
}