Android OpenGL教程-第五课【转】

第五课 3D空间:

 

我们使用多边形和四边形创建3D物体,在这一课里,我们把三角形变为立体的金子塔形状,把四边形变为立方体。

先看看三角形的顶点变成啥了

private float[] mTriangleArray = {

           0.0f,1.0f,0.0f,

           -1.0f,-1.0f,1.0f,

           1.0f,-1.0f,1.0f,

          

           0.0f,1.0f,0.0f,

           1.0f,-1.0f,1.0f,

           1.0f,-1.0f,-1.0f,

          

           0.0f,1.0f,0.0f,

           1.0f,-1.0f,-1.0f,

           -1.0f,-1.0f,-1.0f,

          

           0.0f,1.0f,0.0f,

           -1.0f,-1.0f,-1.0f,

           -1.0f,-1.0f,1.0f

};

private FloatBuffer mTriangleBuffer;

一个四个面,每个面三个点,地面没画。

你们仔细看看每个面,都是按逆时针方向画的。当然,如果你没有增加Cull剔除代码(上节课最后提到),至于顺时针,逆时针都无所谓,都画。但是我们还是推荐使用按照方向来写的array。

 

三角形的颜色数组来了

private float[] mColorArray={

           1.0f,0.0f,0.0f,1.0f,

           0.0f,1.0f,0.0f,1.0f,

           0.0f,0.0f,1.0f,1.0f,

          

           1.0f,0.0f,0.0f,1.0f,

           0.0f,0.0f,1.0f,1.0f,

           0.0f,1.0f,0.0f,1.0f,

          

           1.0f,0.0f,0.0f,1.0f,

           0.0f,1.0f,0.0f,1.0f,

           0.0f,0.0f,1.0f,1.0f,

          

           1.0f,0.0f,0.0f,1.0f,

           0.0f,0.0f,1.0f,1.0f,

           0.0f,1.0f,0.0f,1.0f,    

};

private FloatBuffer mColorBuffer;

注意,同一个点是同一个颜色。

 

立方体的顶点数组:(原文中没有)

// 四边形的顶点数组
private float[] mQuadsArray = {
            //
            1f, 1f, 1f, // 右上
            -1f, 1f, 1f, // 左上
            -1f, -1f, 1f, // 左下
            1f, -1f, 1f,// 右下
            //
            1f, 1f, -1f, // 右上
            1f, 1f, 1f, // 左上
            1f, -1f, 1f, // 左下
            1f, -1f, -1f,// 右下
            //
            -1f, 1f, -1f, // 右上
            1f, 1f, -1f, // 左上
            1f, -1f, -1f, // 左下
            -1f, -1f, -1f,// 右下
            //
            -1f, 1f, 1f, // 右上
            -1f, 1f, -1f, // 左上
            -1f, -1f, -1f, // 左下
            -1f, -1f, 1f, // 右下
            //
            1f, 1f, -1f, // 右上
            -1f, 1f, -1f, // 左上
            -1f, 1f, 1f, // 左下
            1f, 1f, 1f, // 右下
            //
            1f, -1f, 1f, // 右上
            -1f, -1f, 1f, // 左上
            -1f, -1f, -1f, // 左下
            1f, -1f, -1f // 右下
}; // 从这里可以看出,我们按照逆时针的方向画图
private FloatBuffer mQuadsBuffer;

 

立方体的颜色数组来了

private float[] mQuadColorArray={

       0.0f,1.0f,0.0f,1.0f,

       0.0f,1.0f,0.0f,1.0f,

       0.0f,1.0f,0.0f,1.0f,

       0.0f,1.0f,0.0f,1.0f,

      

       1.0f,0.5f,0.0f,1.0f,

       1.0f,0.5f,0.0f,1.0f,

       1.0f,0.5f,0.0f,1.0f,

       1.0f,0.5f,0.0f,1.0f,

      

       1.0f,0.0f,0.0f,1.0f,

       1.0f,0.0f,0.0f,1.0f,

       1.0f,0.0f,0.0f,1.0f,

       1.0f,0.0f,0.0f,1.0f,

      

       1.0f,1.0f,0.0f,1.0f,

       1.0f,1.0f,0.0f,1.0f,

       1.0f,1.0f,0.0f,1.0f,

       1.0f,1.0f,0.0f,1.0f,

      

       0.0f,0.0f,1.0f,1.0f,

       0.0f,0.0f,1.0f,1.0f,

       0.0f,0.0f,1.0f,1.0f,

       0.0f,0.0f,1.0f,1.0f,

      

       1.0f,0.0f,1.0f,1.0f,

       1.0f,0.0f,1.0f,1.0f,

       1.0f,0.0f,1.0f,1.0f,

       1.0f,0.0f,1.0f,1.0f,

};

private FloatBuffer mQuadColorBuffer;

 

不要晕,后面有了纹理就好了,不过这是基础,一定要掌握。

 

画图的代码来了

       gl.glTranslatef(-1.5f, 0.0f, -6.0f);  
       gl.glRotatef(rtri, 0.0f, 1.0f, 0.0f);   //绕Y轴旋转  
//     gl.glColor4f(1f, 1f, 1f, 1f);  
       gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);  
       gl.glEnableClientState(GL10.GL_COLOR_ARRAY);  
        
       gl.glColorPointer(4, GL10.GL_FLOAT, 0, mColorBuffer);  
        
       gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mTriangleBuffer);  
       gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 12);     //四棱锥有4个面,每个面3个点  
        
       gl.glLoadIdentity();  
       gl.glTranslatef(1.5f, 0.0f, -6.0f);  
       gl.glRotatef(rquad, 1.0f, 0.0f, 0.0f);  // gl.glRotatef(rquad, 1.0f, -0.8f, 0.0f); // 斜着旋转
   
       gl.glColorPointer(4, GL10.GL_FLOAT, 0, mQuadColorBuffer);  
       gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mQuadsBuffer);  

       //依次画6个面  
       for (int i=0; i<6; i++){  
           gl.glDrawArrays(GL10.GL_TRIANGLE_FAN, i*4, 4);           
       }  
   
       rtri+=0.2f;  
       rquad-=0.15f;  

 

 

运行结果:

 

 (注:本教程转自其他网页,并加以修改,查看原网页请点击这里

posted @ 2017-03-25 10:28  落枫飘飘  阅读(709)  评论(0编辑  收藏  举报