Libgdx 圆角矩形CircleRect

libgdx提供了ShapeRenderer这个工具，用它可以画点、画线、画圆、画矩形、画椭圆、画扇形，但是没有提供画圆角矩形的方法。

刚开始自己尝试分成8端，4端画直线，4端画扇形，发现多了半径几部分，于是又改成全部画线。

4端弧采用逐个描点实现。

具体代码：

  package com.fxb.newtest;

  import com.badlogic.gdx.ApplicationAdapter;
  import com.badlogic.gdx.Gdx;
  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;

 public class Lib011_CicleRect extends ApplicationAdapter{

     ShapeRenderer rend;

     @Override
     public void create() {
         // TODO Auto-generated method stub
         rend = new ShapeRenderer();
     }

     public void DrawCircleRect( float x, float y, float width, float height, float radius, ShapeRenderer rend, Color color ){
         rend.setColor( color );
         rend.begin(ShapeType.Line);

         //rend.rect( x, y, width, height );
         rend.line( x+radius, y, x+width-radius, y );
         rend.line( x+radius, y+height, x+width-radius, y+height );
         rend.line( x, y+radius, x, y+height-radius );
         rend.line( x+width, y+radius, x+width, y+height-radius );
 /*        
         rend.arc( x+width-radius, y+height-radius, radius, 0, 90 );
         rend.arc( x+radius, y+height-radius, radius, 90, 90 );        
         rend.arc( x+radius, y+radius, radius, 180, 90 );
         rend.arc( x+width-radius, y+radius, radius, 270, 90 );
         */

         int segments = (int)( 6*(float)Math.cbrt( radius ) );

         for( int i=0; i<segments; i++ ){
             float x0 = x+width-radius;
             float y0 = y+height-radius;
             //float angle1 = (float)Math.PI*i*9f/180f;
             //float angle2 = (float)Math.PI*(i+1)*9f/180f;
             float angle1 = (float)Math.PI*i/(2*segments);
             float angle2 = (float)Math.PI*(i+1)/(2*segments);
             rend.line( x0+radius*(float)Math.cos(angle1), y0+radius*(float)Math.sin(angle1), x0+radius*(float)Math.cos(angle2), y0+radius*(float)Math.sin(angle2) );
         }

         for( int i=0; i<segments; i++ ){
             float x0 = x+radius;
             float y0 = y+height-radius;
             float angle1 = (float)Math.PI*(i+segments)/(2*segments);
             float angle2 = (float)Math.PI*(i+segments+1)/(2*segments);
             rend.line( x0+radius*(float)Math.cos(angle1), y0+radius*(float)Math.sin(angle1), x0+radius*(float)Math.cos(angle2), y0+radius*(float)Math.sin(angle2) );
         }

         for( int i=0; i<segments; i++ ){
             float x0 = x+radius;
             float y0 = y+radius;
             float angle1 = (float)Math.PI*(i+segments*2)/(2*segments);
             float angle2 = (float)Math.PI*(i+segments*2+1)/(2*segments);
             rend.line( x0+radius*(float)Math.cos(angle1), y0+radius*(float)Math.sin(angle1), x0+radius*(float)Math.cos(angle2), y0+radius*(float)Math.sin(angle2) );
         }        
         for( int i=0; i<segments; i++ ){
             float x0 = x+width-radius;
             float y0 = y+radius;
             float angle1 = (float)Math.PI*(i+segments*3)/(2*segments);
             float angle2 = (float)Math.PI*(i+segments*3+1)/(2*segments);
             rend.line( x0+radius*(float)Math.cos(angle1), y0+radius*(float)Math.sin(angle1), x0+radius*(float)Math.cos(angle2), y0+radius*(float)Math.sin(angle2) );
         }    

         rend.end();
     }

     @Override
     public void render() {
         // TODO Auto-generated method stub    
         Gdx.gl.glClearColor( 0.5f, 0.5f, 0.5f, 1 );
         Gdx.gl.glClear( GL10.GL_COLOR_BUFFER_BIT );

         DrawCircleRect( 10, 10, 300, 200, 10, rend, Color.RED );
         DrawCircleRect( 100, 60, 300, 200, 20, rend, Color.BLUE );
         DrawCircleRect( 200, 110, 300, 200, 30, rend, Color.CYAN );
         DrawCircleRect( 450, 160, 300, 200, 50, rend, Color.YELLOW );
     }

     @Override
     public void dispose() {
         // TODO Auto-generated method stub
         rend.dispose();
         super.dispose();
     }

 }

运行结果：

4个矩形的圆角半径分别为10,20,30,50像素。

分段数采用源码中的构造方式，

int segments = (int)( 6*(float)Math.cbrt( radius ) );

当然还可以做优化的，以后可以尝试。