Android OpenGL教程 三 3D隨便畫畫

標籤：rip   三角形   2.0   surface   pause   顏色   draw   ntb   視窗   

畫個三棱椎需要四個點，畫四個面

    private float[] mTriangleArray={            -1.0f,-1.0f,0.0f,            1.0f,-1.0f,0.0f,            0.0f,1.0f,0.0f,            0.0f,0.0f,1.0f    };    // 定義三棱椎的4個頂點的顏色    private float[] mColor={            1.0f,0.0f,0.0f,0.0f,            0.0f,1.0f,0.0f,0.0f,            0.0f,0.0f,1.0f,0.0f,            1.0f,1.0f,0.0f,0.0f,    };    private byte[] cubeFacets = new byte[]{            0, 1, 2,            0, 2, 3,            2, 1, 3,            0, 1, 3    };        gl.glDrawElements(GL10.GL_TRIANGLE_STRIP                , cubeFacetsBuffer.remaining(),                GL10.GL_UNSIGNED_BYTE, cubeFacetsBuffer);

如果我們要畫個正方形就要八個點畫六個面，其他代碼不變
// 定義三棱椎的4個頂點的顏色
private float[] mColor={
1.0f,0.0f,0.0f,0.0f,
1.0f,0.0f,0.0f,0.0f,
1.0f,0.0f,0.0f,0.0f,
1.0f,0.0f,0.0f,0.0f,
1.0f,0.0f,0.0f,0.0f,
1.0f,0.0f,0.0f,0.0f,
1.0f,0.0f,0.0f,0.0f,
1.0f,0.0f,0.0f,0.0f
};

    // 定義立方體的8個頂點    float[] cubeVertices = new float[] {            // 上頂面正方形的四個頂點            0.5f, 0.5f, 0.5f,            0.5f, -0.5f, 0.5f,            -0.5f, -0.5f, 0.5f,            -0.5f, 0.5f, 0.5f,            // 下底面正方形的四個頂點            0.5f, 0.5f, -0.5f,            0.5f, -0.5f, -0.5f,            -0.5f, -0.5f, -0.5f,            -0.5f, 0.5f, -0.5f    };    // 定義立方體所需要的6個面（一共是12個三角形所需的頂點）    private byte[] cubeFacets = new byte[]{            0, 2, 1,            0, 2, 3,            2, 7, 3,            2, 7, 6,            0, 7, 3,            0, 7, 4,            4, 6, 5,            4, 6, 7,            1, 4, 0,            1, 4, 5,            1, 6, 2,            1, 6, 5    };

然後加個旋轉方便看清楚全貌
gl.glRotatef(rotate, 1f, 0f, 0f);
rotate++;

完整代碼如下

public class MainActivity extends Activity {
private GLSurfaceView mGLView;

public void onCreate(Bundle savedInstanceState){    super.onCreate(savedInstanceState);    mGLView = new GLSurfaceView(this); //這裡使用的是自訂的GLSurfaceView的子類    mGLView.setRenderer(new GLRenderer());    setContentView(mGLView);}public void onPause(){    super.onPause();    mGLView.onPause();}public void onResume(){    super.onResume();    mGLView.onResume();}public class GLRenderer implements GLSurfaceView.Renderer {    // 定義三棱椎的4個頂點的顏色    private float[] mColor={            1.0f,0.0f,0.0f,0.0f,            1.0f,0.0f,0.0f,0.0f,            1.0f,0.0f,0.0f,0.0f,            1.0f,0.0f,0.0f,0.0f,            1.0f,0.0f,0.0f,0.0f,            1.0f,0.0f,0.0f,0.0f,            1.0f,0.0f,0.0f,0.0f,            1.0f,0.0f,0.0f,0.0f    };    // 定義立方體的8個頂點    float[] cubeVertices = new float[] {            // 上頂面正方形的四個頂點            0.5f, 0.5f, 0.5f,            0.5f, -0.5f, 0.5f,            -0.5f, -0.5f, 0.5f,            -0.5f, 0.5f, 0.5f,            // 下底面正方形的四個頂點            0.5f, 0.5f, -0.5f,            0.5f, -0.5f, -0.5f,            -0.5f, -0.5f, -0.5f,            -0.5f, 0.5f, -0.5f    };    // 定義立方體所需要的6個面（一共是12個三角形所需的頂點）    private byte[] cubeFacets = new byte[]{            0, 2, 1,            0, 2, 3,            2, 7, 3,            2, 7, 6,            0, 7, 3,            0, 7, 4,            4, 6, 5,            4, 6, 7,            1, 4, 0,            1, 4, 5,            1, 6, 2,            1, 6, 5    };    private FloatBuffer mTriangleBuffer;    ByteBuffer cubeFacetsBuffer;    FloatBuffer taperColorsBuffer;    public GLRenderer() {        mTriangleBuffer = floatBufferUtil(cubeVertices);        // 將三棱椎的四個定點的顏色數組封裝成IntBuffer        taperColorsBuffer = floatBufferUtil(mColor);        cubeFacetsBuffer = ByteBuffer.wrap(cubeFacets);    }    @Override    public void onDrawFrame(GL10 gl) {        // 清除螢幕和深度緩衝        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);        // 設定當前矩陣模式為模型視圖。        gl.glMatrixMode(GL10.GL_MODELVIEW);        // 允許設定頂點        //GL10.GL_VERTEX_ARRAY頂點數組        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);        // 允許設定顏色        //GL10.GL_COLOR_ARRAY顏色數組        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);        // 重設當前的模型觀察矩陣        gl.glLoadIdentity();        //將三角形在z軸上移動        gl.glTranslatef(0f, 0.0f, -2.0f);        // 沿著X軸旋轉        gl.glRotatef(rotate, 1f, 0f, 0f);        // 設定三角形        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mTriangleBuffer);        // 設定頂點的顏色資料        gl.glColorPointer(4, GL10.GL_FIXED, 0, taperColorsBuffer);        // 繪製三角形        gl.glDrawElements(GL10.GL_TRIANGLE_STRIP                , cubeFacetsBuffer.remaining(),                GL10.GL_UNSIGNED_BYTE, cubeFacetsBuffer);        // 取消顏色設定        gl.glDisableClientState(GL10.GL_COLOR_ARRAY);        // 取消頂點設定        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);        //繪製結束        gl.glFinish();        rotate++;    }    int rotate = 0;    @Override    public void onSurfaceChanged(GL10 gl, int width, int height) {        float ratio = (float) width / height;        // 設定OpenGL情境的大小,(0,0)表示視窗內部視口的左下角，(w,h)指定了視口的大小        gl.glViewport(0, 0, width, height);        // 設定投影矩陣        gl.glMatrixMode(GL10.GL_PROJECTION);        // 重設投影矩陣        gl.glLoadIdentity();        // 設定視口的大小        gl.glFrustumf(-ratio, ratio, -1, 1, 1, 10);        //以下兩句聲明，以後所有的變換都是針對模型(即我們繪製的圖形)        gl.glMatrixMode(GL10.GL_MODELVIEW);        gl.glLoadIdentity();    }    @Override    public void onSurfaceCreated(GL10 gl, EGLConfig config) {        // 設定白色為清屏        gl.glClearColor(1, 1, 1, 1);    }}// 定義一個工具方法，將float[]數群組轉換為OpenGL ES所需的FloatBufferprivate FloatBuffer floatBufferUtil(float[] arr){    FloatBuffer mBuffer;    // 初始化ByteBuffer，長度為arr數組的長度*4，因為一個int佔4個位元組    ByteBuffer qbb = ByteBuffer.allocateDirect(arr.length * 4);    // 數組排列用nativeOrder    qbb.order(ByteOrder.nativeOrder());    mBuffer = qbb.asFloatBuffer();    mBuffer.put(arr);    mBuffer.position(0);    return mBuffer;}// 定義一個工具方法，將int[]數群組轉換為OpenGL ES所需的IntBufferprivate IntBuffer intBufferUtil(int[] arr){    IntBuffer mBuffer;    // 初始化ByteBuffer，長度為arr數組的長度*4，因為一個int佔4個位元組    ByteBuffer qbb = ByteBuffer.allocateDirect(arr.length * 4);    // 數組排列用nativeOrder    qbb.order(ByteOrder.nativeOrder());    mBuffer = qbb.asIntBuffer();    mBuffer.put(arr);    mBuffer.position(0);    return mBuffer;}

}

Android OpenGL教程 三 3D隨便畫畫