TestMathUtils.java

/*
  TestMathUtils.java

  (c) 2012 Edward Swartz

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package ejs.base.internal.test;

import static org.junit.Assert.*;

import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;

import org.junit.Test;

import ejs.base.utils.MathUtils;

/**
 * @author ejs
 *
 */
public class TestMathUtils {

	@Test
	public void testRotatePointsCentered() {
		Point2D.Double ans;
		
		ans = MathUtils.rotatePoint(0, 0, 10, 40, 0);
		assertEquals(10., ans.x, 0.01);
		assertEquals(40., ans.y, 0.01);
		
		// rotate "_" counter-clockwise quarter turn -- should point up (screen-wise)
		ans = MathUtils.rotatePoint(0, 0, 40, 0, Math.PI / 2);
		assertEquals(0., ans.x, 0.01);
		assertEquals(40., ans.y, 0.01);
		
		ans = MathUtils.rotatePoint(0, 0, 40, 0, Math.PI);
		assertEquals(-40., ans.x, 0.01);
		assertEquals(0., ans.y, 0.01);
		
		ans = MathUtils.rotatePoint(0, 0, 40, 0, Math.PI * 3 / 2);
		assertEquals(0., ans.x, 0.01);
		assertEquals(-40., ans.y, 0.01);
		
		// turn "/" clockwise one-eighth turn; should be on X axis
		ans = MathUtils.rotatePoint(0, 0, Math.sqrt(2), Math.sqrt(2), -Math.PI / 4);
		assertEquals(2., ans.x, 0.01);
		assertEquals(0., ans.y, 0.01);
	}
	

	@Test
	public void testRotatePointsOffCenter() {
		Point2D.Double ans;
		
		ans = MathUtils.rotatePoint(100, 100, 10, 40, 0);
		assertEquals(110., ans.x, 0.01);
		assertEquals(140., ans.y, 0.01);
		
		// rotate "_" counter-clockwise quarter turn -- should point up (screen-wise)
		
		// given this center, we can assume the bounds is e.g [-50 to 35] x [-5 to 5],
		// so after rotating, 
		ans = MathUtils.rotatePoint(-5, -5, 40, 0, Math.PI / 2);
		assertEquals(-5., ans.x, 0.01);
		assertEquals(35., ans.y, 0.01);
		
		// turn "/" clockwise one-eighth turn; should be on X axis
		ans = MathUtils.rotatePoint(100, 100, Math.sqrt(2), Math.sqrt(2), -Math.PI / 4);
		assertEquals(102., ans.x, 0.01);
		assertEquals(100., ans.y, 0.01);
	}
	

	@Test
	public void testRotateRects() {
		Rectangle2D ans;
		
		// no rot
		ans = MathUtils.rotateRectangle(
				new Rectangle2D.Double(40, 75, 100, 10),
				new Point2D.Double(0, 5),
				0);

		assertEquals(40., ans.getX(), 0.01);
		assertEquals(75., ans.getY(), 0.01);
		assertEquals(100., ans.getWidth(), 0.01);
		assertEquals(10., ans.getHeight(), 0.01);
		
		// rotate 90 degrees left
		ans = MathUtils.rotateRectangle(
				new Rectangle2D.Double(45, 70, 100, 10),
				new Point2D.Double(0, 5),
				Math.PI / 2);

		assertEquals(40., ans.getX(), 0.01);
		assertEquals(75. - 100., ans.getY(), 0.01);
		assertEquals(10., ans.getWidth(), 0.01);
		assertEquals(100., ans.getHeight(), 0.01);
		

		// rotate 180 degrees 
		ans = MathUtils.rotateRectangle(
				new Rectangle2D.Double(45, 70, 100, 10),
				new Point2D.Double(0, 5),
				Math.PI);

		assertEquals(45 - 100., ans.getX(), 0.01);
		assertEquals(70., ans.getY(), 0.01);
		assertEquals(100., ans.getWidth(), 0.01);
		assertEquals(10., ans.getHeight(), 0.01);
	}
	
	@Test
	public void testEllipseCircumference() {
		// a circle
		assertEquals(Math.PI * 10 * 2, MathUtils.ellipseCircumference(10, 10), 0.01);
		
		// degenerate ellipse, a line of length 20, going forward and backward
		assertEquals(40, MathUtils.ellipseCircumference(10, 0), 0.1);
	}
}