libgdx学习记录25——Rectangle与Circle是否重叠

Rect与Circle重叠有三种情况：

1. Rect至少有一个角在Circle里面

2. Circle与Rect的左边或右边相交，或者Circle在Rect内

3. Circle与Rect的顶边或底边相交，或者Circle在Rect内

判断代码：

 1     public static boolean IsInside( float x, float y, Circle circle ){
 2         float disX = x - circle.x;
 3         float disY = y - circle.y;
 4         return disX*disX + disY*disY <= circle.radius*circle.radius;
 5     }
 6     
 7     public static float Distance( float x1, float y1, float x2, float y2 ){
 8         return (float)Math.sqrt( (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1) );
 9     }
10     
11     public static boolean IsOverlap( Rectangle rect0, Circle circle0 ){
12         float x1 = rect0.x, y1 = rect0.y, w = rect0.width, h = rect0.height;
13         float cx1 = x1+w/2, cy1 = y1+h/2;
14         float x2 = circle0.x, y2 = circle0.y, r = circle0.radius;
15         /////overlap with the corners
16         if( IsInside(x1,y1,circle0) || IsInside(x1+w,y1,circle0) || IsInside(x1,y1+h,circle0) || IsInside(x1+w,y1+h,circle0) ){
17             return true;
18         }
19         ////overlap with the left or the right edge or s inside of the rect
20         if( Distance( cx1, cy1, x2, y2 )<w/2+r && Math.abs( cy1-y2 )<h/2 ){
21             return true;
22         }
23         ////overlap with the top or the bottom edge or s inside of the rect
24         if( Distance( cx1, cy1, x2, y2 )<h/2+r && Math.abs( cx1-x2 )<w/2 ){
25             return true;
26         }
27         
28         return false;
29     }

完整实例代码：

  1 package com.fxb.newtest;
  2 
  3 import com.badlogic.gdx.ApplicationAdapter;
  4 import com.badlogic.gdx.Gdx;
  5 import com.badlogic.gdx.Input;
  6 import com.badlogic.gdx.graphics.Color;
  7 import com.badlogic.gdx.graphics.GL10;
  8 import com.badlogic.gdx.graphics.g2d.BitmapFont;
  9 import com.badlogic.gdx.graphics.g2d.SpriteBatch;
 10 import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
 11 import com.badlogic.gdx.graphics.glutils.ShapeRenderer.ShapeType;
 12 import com.badlogic.gdx.math.Circle;
 13 import com.badlogic.gdx.math.Rectangle;
 14 
 15 public class Lib032_CircleRect extends ApplicationAdapter{
 16 
 17     Rectangle rect;
 18     Circle circle;
 19     ShapeRenderer rend;
 20     SpriteBatch batch;
 21     BitmapFont font;
 22     
 23     public static boolean IsInside( float x, float y, Circle circle ){
 24         float disX = x - circle.x;
 25         float disY = y - circle.y;
 26         return disX*disX + disY*disY <= circle.radius*circle.radius;
 27     }
 28     
 29     public static float Distance( float x1, float y1, float x2, float y2 ){
 30         return (float)Math.sqrt( (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1) );
 31     }
 32     
 33     public static boolean IsOverlap( Rectangle rect0, Circle circle0 ){
 34         float x1 = rect0.x, y1 = rect0.y, w = rect0.width, h = rect0.height;
 35         float cx1 = x1+w/2, cy1 = y1+h/2;
 36         float x2 = circle0.x, y2 = circle0.y, r = circle0.radius;
 37         /////overlap with the corners
 38         if( IsInside(x1,y1,circle0) || IsInside(x1+w,y1,circle0) || IsInside(x1,y1+h,circle0) || IsInside(x1+w,y1+h,circle0) ){
 39             return true;
 40         }
 41         ////overlap with the left or the right edge or s inside of the rect
 42         if( Distance( cx1, cy1, x2, y2 )<w/2+r && Math.abs( cy1-y2 )<h/2 ){
 43             return true;
 44         }
 45         ////overlap with the top or the bottom edge or s inside of the rect
 46         if( Distance( cx1, cy1, x2, y2 )<h/2+r && Math.abs( cx1-x2 )<w/2 ){
 47             return true;
 48         }
 49         
 50         return false;
 51     }
 52     
 53     @Override
 54     public void create() {
 55         // TODO Auto-generated method stub
 56         super.create();
 57         
 58         rect = new Rectangle( 10, 10, 100, 50 );
 59         circle = new Circle( 400, 240, 100 );
 60         
 61         rend = new ShapeRenderer();
 62         batch = new SpriteBatch();
 63         font = new BitmapFont();
 64         font.setColor( Color.BLACK );
 65         
 66     }
 67 
 68     @Override
 69     public void render() {
 70         // TODO Auto-generated method stub
 71         super.render();
 72         
 73         Gdx.gl.glClearColor( 1, 1, 1, 1 );
 74         Gdx.gl.glClear( GL10.GL_COLOR_BUFFER_BIT );
 75         
 76         float step = 1.5f;
 77         if( Gdx.input.isKeyPressed( Input.Keys.LEFT ) ){
 78             rect.x -= step;
 79         }
 80         else if( Gdx.input.isKeyPressed( Input.Keys.RIGHT ) ){
 81             rect.x += step;
 82         }        
 83         else if( Gdx.input.isKeyPressed( Input.Keys.UP ) ){
 84             rect.y +=step;
 85         }
 86         else if( Gdx.input.isKeyPressed( Input.Keys.DOWN ) ){
 87             rect.y -= step;
 88         }
 89         
 90         if( Gdx.input.isKeyPressed( Input.Keys.A ) ){
 91             rect.width -= step;
 92         }
 93         else if( Gdx.input.isKeyPressed( Input.Keys.D ) ){
 94             rect.width += step;
 95         }        
 96         else if( Gdx.input.isKeyPressed( Input.Keys.W ) ){
 97             rect.height +=step;
 98         }
 99         else if( Gdx.input.isKeyPressed( Input.Keys.S ) ){
100             rect.height -= step;
101         }
102         
103         rend.begin( ShapeType.Line );
104         rend.setColor( Color.BLUE );
105         rend.rect( rect.x, rect.y, rect.width, rect.height );
106         rend.circle( circle.x, circle.y, circle.radius );
107         rend.end();
108         
109         String str;
110         if( IsOverlap( rect, circle ) ){
111             str = "true";
112         }
113         else{
114             str = "false";
115         }
116         
117         batch.begin();
118         font.draw( batch, str, 750, 20 );
119         batch.end();
120         
121     }
122 
123     @Override
124     public void dispose() {
125         // TODO Auto-generated method stub
126         super.dispose();
127     }
128 
129 }

运行结果：

演示了四种相交的情形，其他右下角显示为false