Java tutorial
/******************************************************************************* * 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.math.Vector2; import com.badlogic.gdx.utils.NumberUtils; /** A convenient 2D ellipse class, based on the circle class * @author tonyp7 */ public class Ellipse implements Serializable, Shape2D { public float x, y; public float width, height; private static final long serialVersionUID = 7381533206532032099L; /** Construct a new ellipse with all values set to zero */ public Ellipse() { } /** Copy constructor * * @param ellipse Ellipse to construct a copy of. */ public Ellipse(Ellipse ellipse) { this.x = ellipse.x; this.y = ellipse.y; this.width = ellipse.width; this.height = ellipse.height; } /** Constructs a new ellipse * * @param x X coordinate * @param y Y coordinate * @param width Width in pixels * @param height Height in pixels */ public Ellipse(float x, float y, float width, float height) { this.x = x; this.y = y; this.width = width; this.height = height; } /** Costructs a new ellipse * * @param position Position vector * @param width Width in pixels * @param height Height in pixels */ public Ellipse(Vector2 position, float width, float height) { this.x = position.x; this.y = position.y; this.width = width; this.height = height; } public Ellipse(Vector2 position, Vector2 size) { this.x = position.x; this.y = position.y; this.width = size.x; this.height = size.y; } /** Constructs a new {@link Ellipse} from the position and radius of a {@link Circle} (since circles are special cases of * ellipses). * @param circle The circle to take the values of */ public Ellipse(Circle circle) { this.x = circle.x; this.y = circle.y; this.width = circle.radius; this.height = circle.radius; } /** Checks whether or not this ellipse contains the given point. * * @param x X coordinate * @param y Y coordinate * * @return true if this ellipse contains the given point; false otherwise. */ public boolean contains(float x, float y) { x = x - this.x; y = y - this.y; return (x * x) / (width * 0.5f * width * 0.5f) + (y * y) / (height * 0.5f * height * 0.5f) <= 1.0f; } /** Checks whether or not this ellipse contains the given point. * * @param point Position vector * * @return true if this ellipse contains the given point; false otherwise. */ public boolean contains(Vector2 point) { return contains(point.x, point.y); } /** Sets a new position and size for this ellipse. * * @param x X coordinate * @param y Y coordinate * @param width Width in pixels * @param height Height in pixels */ public void set(float x, float y, float width, float height) { this.x = x; this.y = y; this.width = width; this.height = height; } /** Sets a new position and size for this ellipse based upon another ellipse. * * @param ellipse The ellipse to copy the position and size of. */ public void set(Ellipse ellipse) { x = ellipse.x; y = ellipse.y; width = ellipse.width; height = ellipse.height; } public void set(Circle circle) { this.x = circle.x; this.y = circle.y; this.width = circle.radius; this.height = circle.radius; } public void set(Vector2 position, Vector2 size) { this.x = position.x; this.y = position.y; this.width = size.x; this.height = size.y; } /** Sets the x and y-coordinates of ellipse center from a {@link Vector2}. * @param position The position vector * @return this ellipse for chaining */ public Ellipse setPosition(Vector2 position) { this.x = position.x; this.y = position.y; return this; } /** Sets the x and y-coordinates of ellipse center * @param x The x-coordinate * @param y The y-coordinate * @return this ellipse for chaining */ public Ellipse setPosition(float x, float y) { this.x = x; this.y = y; return this; } /** Sets the width and height of this ellipse * @param width The width * @param height The height * @return this ellipse for chaining */ public Ellipse setSize(float width, float height) { this.width = width; this.height = height; return this; } /** @return The area of this {@link Ellipse} as {@link MathUtils#PI} * {@link Ellipse#width} * {@link Ellipse#height} */ public float area() { return MathUtils.PI * (this.width * this.height) / 4; } /** Approximates the circumference of this {@link Ellipse}. Oddly enough, the circumference of an ellipse is actually difficult * to compute exactly. * @return The Ramanujan approximation to the circumference of an ellipse if one dimension is at least three times longer than * the other, else the simpler approximation */ public float circumference() { float a = this.width / 2; float b = this.height / 2; if (a * 3 > b || b * 3 > a) { // If one dimension is three times as long as the other... return (float) (MathUtils.PI * ((3 * (a + b)) - Math.sqrt((3 * a + b) * (a + 3 * b)))); } else { // We can use the simpler approximation, then return (float) (MathUtils.PI2 * Math.sqrt((a * a + b * b) / 2)); } } @Override public boolean equals(Object o) { if (o == this) return true; if (o == null || o.getClass() != this.getClass()) return false; Ellipse e = (Ellipse) o; return this.x == e.x && this.y == e.y && this.width == e.width && this.height == e.height; } @Override public int hashCode() { final int prime = 53; int result = 1; result = prime * result + NumberUtils.floatToRawIntBits(this.height); result = prime * result + NumberUtils.floatToRawIntBits(this.width); result = prime * result + NumberUtils.floatToRawIntBits(this.x); result = prime * result + NumberUtils.floatToRawIntBits(this.y); return result; } }