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：
public static boolean IsInside( float x, float y, Circle circle ){
float disX = x - circle.x;
float disY = y - circle.y;
return disX*disX + disY*disY <= circle.radius*circle.radius;
}
public static float Distance( float x1, float y1, float x2, float y2 ){
return (float)Math.sqrt( (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1) );
}
public static boolean IsOverlap( Rectangle rect0, Circle circle0 ){
float x1 = rect0.x, y1 = rect0.y, w = rect0.width, h = rect0.height;
float cx1 = x1+w/2, cy1 = y1+h/2;
float x2 = circle0.x, y2 = circle0.y, r = circle0.radius;
/////overlap with the corners
if( IsInside(x1,y1,circle0) || IsInside(x1+w,y1,circle0) || IsInside(x1,y1+h,circle0) || IsInside(x1+w,y1+h,circle0) ){
return true;
}
////overlap with the left or the right edge or s inside of the rect
if( Distance( cx1, cy1, x2, y2 )<w/2+r && Math.abs( cy1-y2 )<h/2 ){
return true;
}
////overlap with the top or the bottom edge or s inside of the rect
if( Distance( cx1, cy1, x2, y2 )<h/2+r && Math.abs( cx1-x2 )<w/2 ){
return true;
}
return false;
}
完整实例代码：
package com.fxb.newtest; import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.g2d.BitmapFont;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
import com.badlogic.gdx.graphics.glutils.ShapeRenderer.ShapeType;
import com.badlogic.gdx.math.Circle;
import com.badlogic.gdx.math.Rectangle; public class Lib032_CircleRect extends ApplicationAdapter{ Rectangle rect;
Circle circle;
ShapeRenderer rend;
SpriteBatch batch;
BitmapFont font; public static boolean IsInside( float x, float y, Circle circle ){
float disX = x - circle.x;
float disY = y - circle.y;
return disX*disX + disY*disY <= circle.radius*circle.radius;
} public static float Distance( float x1, float y1, float x2, float y2 ){
return (float)Math.sqrt( (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1) );
} public static boolean IsOverlap( Rectangle rect0, Circle circle0 ){
float x1 = rect0.x, y1 = rect0.y, w = rect0.width, h = rect0.height;
float cx1 = x1+w/2, cy1 = y1+h/2;
float x2 = circle0.x, y2 = circle0.y, r = circle0.radius;
/////overlap with the corners
if( IsInside(x1,y1,circle0) || IsInside(x1+w,y1,circle0) || IsInside(x1,y1+h,circle0) || IsInside(x1+w,y1+h,circle0) ){
return true;
}
////overlap with the left or the right edge or s inside of the rect
if( Distance( cx1, cy1, x2, y2 )<w/2+r && Math.abs( cy1-y2 )<h/2 ){
return true;
}
////overlap with the top or the bottom edge or s inside of the rect
if( Distance( cx1, cy1, x2, y2 )<h/2+r && Math.abs( cx1-x2 )<w/2 ){
return true;
} return false;
} @Override
public void create() {
// TODO Auto-generated method stub
super.create(); rect = new Rectangle( 10, 10, 100, 50 );
circle = new Circle( 400, 240, 100 ); rend = new ShapeRenderer();
batch = new SpriteBatch();
font = new BitmapFont();
font.setColor( Color.BLACK ); } @Override
public void render() {
// TODO Auto-generated method stub
super.render(); Gdx.gl.glClearColor( 1, 1, 1, 1 );
Gdx.gl.glClear( GL10.GL_COLOR_BUFFER_BIT ); float step = 1.5f;
if( Gdx.input.isKeyPressed( Input.Keys.LEFT ) ){
rect.x -= step;
}
else if( Gdx.input.isKeyPressed( Input.Keys.RIGHT ) ){
rect.x += step;
}
else if( Gdx.input.isKeyPressed( Input.Keys.UP ) ){
rect.y +=step;
}
else if( Gdx.input.isKeyPressed( Input.Keys.DOWN ) ){
rect.y -= step;
} if( Gdx.input.isKeyPressed( Input.Keys.A ) ){
rect.width -= step;
}
else if( Gdx.input.isKeyPressed( Input.Keys.D ) ){
rect.width += step;
}
else if( Gdx.input.isKeyPressed( Input.Keys.W ) ){
rect.height +=step;
}
else if( Gdx.input.isKeyPressed( Input.Keys.S ) ){
rect.height -= step;
} rend.begin( ShapeType.Line );
rend.setColor( Color.BLUE );
rend.rect( rect.x, rect.y, rect.width, rect.height );
rend.circle( circle.x, circle.y, circle.radius );
rend.end(); String str;
if( IsOverlap( rect, circle ) ){
str = "true";
}
else{
str = "false";
} batch.begin();
font.draw( batch, str, 750, 20 );
batch.end(); } @Override
public void dispose() {
// TODO Auto-generated method stub
super.dispose();
} }
运行结果：
演示了四种相交的情形，其他右下角显示为false