Android 3D 旋轉的三角形（三）

立體

package com.sunny;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.opengl.GLSurfaceView;
public class VortexRenderer implements GLSurfaceView.Renderer{
    private static final String LOG_TAG=VortexRenderer.class.getSimpleName();
    
    private ShortBuffer _indexBuffer;//儲存索引
    
    private FloatBuffer _vertexBuffer;//儲存定點座標
    
    private FloatBuffer _colorBuffer;
    //private short[] _indicesArray={0,1,2};
    private int _nrOfVertices=0;//定義需要多少個頂點.對於一個三角形來說,一共需要三個頂點
   
    
    private float _xAngle;
    private float _yAngle;
    
    public float getXAngle() {
        return _xAngle;
    }

    public void setXAngle(float angle) {
        this._xAngle = angle;
    }

    public float getYAngle() {
        return _yAngle;
    }

    public void setYAngle(float angle) {
        this._yAngle = angle;
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {//surface建立以後調用
        // TODO Auto-generated method stub
        // enable the differentiation of which side may be visible
         gl.glEnable(GL10.GL_CULL_FACE);//enable了culling面，以保證只有一面
        // which is the front? the one which is drawn counter clockwise
         gl.glFrontFace(GL10.GL_CCW);//GL_CCW表示逆時針
        // which one should NOT be drawn
         gl.glCullFace(GL10.GL_BACK);//GL_FRONT_AND_BACK
        
         gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
         gl.glEnableClientState(GL10.GL_COLOR_ARRAY);
        
         initTriangle();
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int w, int h) {//surface發生改變以後調用，例如從豎屏切換到橫屏的時候
        // TODO Auto-generated method stub
        gl.glViewport(0,0,w,h);
    }

    @Override
    public void onDrawFrame(GL10 gl) {//當任何時候調用一個畫圖方法的時候
        // define the color we want to be displayed as the "clipping wall"
        gl.glClearColor(0f, 0f, 0f, 1.0f);
        // reset the matrix - good to fix the rotation to a static angle
        gl.glLoadIdentity();
        // clear the color buffer to show the ClearColor we called above...
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
        // set rotation
        gl.glRotatef(_xAngle, 1f, 0f, 0f);
        gl.glRotatef(_yAngle, 0f, 1f, 0f);
       
        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, _vertexBuffer);
        gl.glColorPointer(4, GL10.GL_FLOAT, 0, _colorBuffer);
        gl.glDrawElements(GL10.GL_TRIANGLES, _nrOfVertices, GL10.GL_UNSIGNED_SHORT, _indexBuffer);
    }

    private void initTriangle(){
        float[] coords={//座標
                -0.5f, -0.5f, 0.5f, // 0
                0.5f, -0.5f, 0.5f, // 1
                0f, -0.5f, -0.5f, // 2
                0f, 0.5f, 0f, // 3   
        };
        _nrOfVertices=coords.length;//更加的動態
        float[] colors={//顏色
                1f, 0f, 0f, 1f, // point 0 red
                0f, 1f, 0f, 1f, // point 1 green
                0f, 0f, 1f, 1f, // point 2 blue
                1f, 1f, 1f, 1f, // point 3 white
        };
        short[] indices=new short[]{//定點數
                0, 1, 3, // rwg
                0, 2, 1, // rbg
                0, 3, 2, // rbw
                1, 2, 3, // bwg
        };
        //為這裡兩個buffer分配必須的記憶體
        // float has 4 bytes
        ByteBuffer vbb=ByteBuffer.allocateDirect(_nrOfVertices*3*4);
        vbb.order(ByteOrder.nativeOrder());
        _vertexBuffer=vbb.asFloatBuffer();
        // short has 2 bytes
        ByteBuffer ibb=ByteBuffer.allocateDirect(_nrOfVertices*2);
        ibb.order(ByteOrder.nativeOrder());
        _indexBuffer=ibb.asShortBuffer();
       
        ByteBuffer cbb=ByteBuffer.allocateDirect(4*_nrOfVertices*4);
        cbb.order(ByteOrder.nativeOrder());
        _colorBuffer=cbb.asFloatBuffer();
       
       
        _vertexBuffer.put(coords);
        _indexBuffer.put(indices);
        _colorBuffer.put(colors);
       
        _vertexBuffer.position(0);
        _indexBuffer.position(0);
        _colorBuffer.position(0);
    }

}