CollisionHelper for Libgdx

Shared Code
#1

Hey, this is a class I made useful for collisions. It’s really efficient as you don’t need a Rectangle for every Entity you have. The entire game collisions can be managed with just 2 rectangles and 2 circles.

It also has a method to check if a rectangle overlaps a circle, really useful.

You can use them for your entities or buttons.


import net.autlos.sgf2.entities.Entity;

import com.badlogic.gdx.math.Circle;
import com.badlogic.gdx.math.Rectangle;
import com.badlogic.gdx.math.Vector2;

public class CollisionHelper {
	public static final Rectangle rectA = new Rectangle();
	public static final Rectangle rectB = new Rectangle();
	public static final Circle circA = new Circle();
	public static final Circle circB = new Circle();

	public static boolean collidesRectangles(Entity entityA, Entity entityB) {
		entityA.setBoundingRectangle(rectA);
		entityB.setBoundingRectangle(rectB);
		return rectA.overlaps(rectB);
	}

	public static boolean collidesCircles(Entity entityA, Entity entityB) {
		entityA.setBoundingCircle(circA);
		entityB.setBoundingCircle(circB);
		return circA.overlaps(circB);
	}

	public static boolean collidesCircleRectangle(Entity circleEntity, Entity rectangleEntity){
		circleEntity.setBoundingCircle(circA);
		rectangleEntity.setBoundingRectangle(rectA);	
		
		float circleDistanceX = Math.abs(circA.x - rectA.x - rectA.width/2);
		float circleDistanceY = Math.abs(circA.y - rectA.y - rectA.height/2);
		
		if(circleDistanceX > (rectA.width/2 + circA.radius) || circleDistanceY > (rectA.height/2 + circA.radius))
			return false;
		if(circleDistanceX <= (rectA.width/2) || circleDistanceX <= (rectA.height/2))
			return true;
		
		float cornerDistance = (circleDistanceX - rectA.width/2)*(circleDistanceX - rectA.width/2) 
				+ (circleDistanceY - rectA.height/2)*(circleDistanceY - rectA.height/2);		
		
		return (cornerDistance <= (circA.radius * circA.radius));
	}
	
	public static boolean isTouchingCircle(Entity circEntity, Vector2 position){
		return isTouchingCircle(circEntity, position.x, position.y);
	}

	public static boolean isTouchingRectangle(Entity rectEntity, Vector2 position){
		return isTouchingRectangle(rectEntity, position.x, position.y);
	}
	
	/**
	 * Returns true if the rectangle contains the given coordinates.
	 * @param rectEntity
	 * @param x
	 * @param y
	 * @return
	 */
	public static boolean isTouchingRectangle(Entity rectEntity, float x, float y) {
		rectEntity.setBoundingRectangle(rectA);
		return rectA.contains(x, y);
	}

	/**
	 * Returns true if the circle contains the given position
	 * @param circEntity
	 * @param x
	 * @param y
	 * @return
	 */
	public static boolean isTouchingCircle(Entity circEntity, float x, float y) {
		circEntity.setBoundingCircle(circA);
		return circA.contains(x, y);
	}
}

You don’t need my Entity class, but you might want to see “setBoundingCircle” and “setBoundingRectangle” methods:


   public void setBoundingRectangle(Rectangle boundingRectangle){
		boundingRectangle.set(position.x, position.y, width, height);
	}
	
	public void setBoundingCircle(Circle boundingCircle){
		boundingCircle.set(position.x + width / 2, position.y + height / 2, width/2);	
	}