libgdx中Math封装了Polygon这个类，它是由多个定点进行描述实现的，在进行物体间的碰撞时，物体轮廓有时候是不规则的，这时候可以用一个多边形勾勒出其大概的轮廓，对其进行模拟。
Polygon内部自带是否包含点contains这个函数，通过这个函数我们可以判断两个多变行是否碰撞，即检测两个多边形的每个点是否在另一个多边形中。
检测代码：
public static boolean isOverlap(Polygon polygon1, Polygon polygon2){
for(int i=0; i<polygon2.getVertices().length; i+=2){
if( polygon1.contains(polygon2.getVertices()[i], polygon2.getVertices()[i+1]) ){
return true;
}
}
for(int i=0; i<polygon1.getVertices().length; i+=2){
if( polygon2.contains(polygon1.getVertices()[i], polygon1.getVertices()[i+1]) ){
return true;
}
}
return false;
}
实例代码：
package com.fxb.Gam003; import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.InputAdapter;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
import com.badlogic.gdx.graphics.glutils.ShapeRenderer.ShapeType;
import com.badlogic.gdx.math.Polygon;
import com.badlogic.gdx.math.Vector2; public class Lib051_Polygon extends ApplicationAdapter{ Polygon polygon1, polygon2;
ShapeRenderer rend;
float[] vertices1, vertices2;
Vector2 point = new Vector2(100, 50); InputAdapter adapter = new InputAdapter(){
@Override
public boolean touchDown(int screenX, int screenY, int pointer, int button) {
for(int i=0; i<polygon2.getVertices().length; i+=2){
polygon2.getVertices()[i ] += screenX - point.x;
polygon2.getVertices()[i+1] += Gdx.graphics.getHeight()-screenY - point.y;
}
polygon2.dirty(); point.set(screenX, Gdx.graphics.getHeight()-screenY);
//polygon2.setVertices(new float[]{ 100+point.x, 50+point.y, 200+point.x, 70+point.y, 300+point.x, 150+point.y, 150+point.x, 100+point.y}); return true;
} }; @Override
public void create() {
// TODO Auto-generated method stub
super.create(); polygon1 = new Polygon();
vertices1 = new float[]{ 100, 100, 200, 100, 300, 300, 100, 200 };
polygon1.setVertices(vertices1); vertices2 = new float[]{ 100, 50, 200, 70, 300, 150, 150, 100};
polygon2 = new Polygon(vertices2); rend = new ShapeRenderer();
Gdx.input.setInputProcessor(adapter);
} public static boolean isOverlap(Polygon polygon1, Polygon polygon2){
for(int i=0; i<polygon2.getVertices().length; i+=2){
if( polygon1.contains(polygon2.getVertices()[i], polygon2.getVertices()[i+1]) ){
return true;
}
}
for(int i=0; i<polygon1.getVertices().length; i+=2){
if( polygon2.contains(polygon1.getVertices()[i], polygon1.getVertices()[i+1]) ){
return true;
}
}
return false;
} @Override
public void render() {
// TODO Auto-generated method stub
super.render();
Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
Gdx.gl.glClearColor(1, 1, 1, 1); rend.begin(ShapeType.Line);
rend.setColor(Color.RED);
for(int i=0; i<polygon1.getVertices().length; i+=2){
rend.line(vertices1[i], vertices1[i+1], vertices1[(i+2)%vertices1.length], vertices1[(i+3)%vertices1.length]);
} float[] vertices3 = polygon2.getVertices();
for(int i=0; i<polygon2.getVertices().length; i+=2){
rend.line(vertices3[i], vertices3[i+1], vertices3[(i+2)%vertices3.length], vertices3[(i+3)%vertices3.length]);
}
rend.end(); //if(polygon1.contains(point.x, point.y)){
if( isOverlap(polygon1, polygon2) ){
rend.setColor(Color.RED);
}else{
rend.setColor(Color.BLUE);
}
rend.begin(ShapeType.Filled);
rend.circle(point.x, point.y, 5);
rend.end(); } @Override
public void dispose() {
// TODO Auto-generated method stub
super.dispose();
} }
运行结果：
展示了三种情况，当然，这里只是进行简单的测试，可以任意绘制多边形进行检测。