Android OpenGL 教程 第五课

Android OpenGL 教程

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

[java] view plaincopy

1.     gl.glTranslatef(-1.5f, 0.0f, -6.0f);  
2.        gl.glRotatef(rtri, 0.0f, 1.0f, 0.0f);                  //绕Y轴旋转  
3. //     gl.glColor4f(1f, 1f, 1f, 1f);  
4.        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);  
5.        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);  
6.         
7.        gl.glColorPointer(4, GL10.GL_FLOAT, 0, mColorBuffer);  
8.         
9.        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mTriangleBuffer);  
10.        gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 12);     //四棱锥有4个面，每个面3个点  
11.         
12.        gl.glLoadIdentity();  
13.        gl.glTranslatef(1.5f, 0.0f, -6.0f);  
14.        gl.glRotatef(rquad, 1.0f, 0.0f, 0.0f);  
15.    
16.        gl.glColorPointer(4, GL10.GL_FLOAT, 0, mQuadColorBuffer);  
17.        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mQuadsBuffer);  
18. //依次画6个面  
19.        for (int i=0; i<6; i++){  
20.            gl.glDrawArrays(GL10.GL_TRIANGLE_FAN, i*4, 4);           
21.        }  
22.    
23.        rtri+=0.2f;  
24.        rquad-=0.15f;