android OpenGL es lession5

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.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;