Wrapper activity demonstrating the use of {@link GLSurfaceView}, a view that uses OpenGL drawing into a dedicated surface. : OpenGL « 2D Graphics « Android

1. Android
2. 2D Graphics
3. OpenGL

Wrapper activity demonstrating the use of {@link GLSurfaceView}, a view that uses OpenGL drawing into a dedicated surface.

   
/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package app.test;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.IntBuffer;

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

import android.app.Activity;
import android.content.Context;
import android.opengl.GLSurfaceView;
import android.os.Bundle;
import android.view.MotionEvent;

/**
 * Wrapper activity demonstrating the use of {@link GLSurfaceView}, a view that
 * uses OpenGL drawing into a dedicated surface.
 * 
 * Shows: + How to redraw in response to user input.
 */
public class Test extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Create our Preview view and set it as the content of our
    // Activity
    mGLSurfaceView = new TouchSurfaceView(this);
    setContentView(mGLSurfaceView);
    mGLSurfaceView.requestFocus();
    mGLSurfaceView.setFocusableInTouchMode(true);
  }

  @Override
  protected void onResume() {
    // Ideally a game should implement onResume() and onPause()
    // to take appropriate action when the activity looses focus
    super.onResume();
    mGLSurfaceView.onResume();
  }

  @Override
  protected void onPause() {
    // Ideally a game should implement onResume() and onPause()
    // to take appropriate action when the activity looses focus
    super.onPause();
    mGLSurfaceView.onPause();
  }

  private GLSurfaceView mGLSurfaceView;
}

/**
 * A vertex shaded cube.
 */
class Cube {
  public Cube() {
    int one = 0x10000;
    int vertices[] = { -one, -one, -one, one, -one, -one, one, one, -one,
        -one, one, -one, -one, -one, one, one, -one, one, one, one,
        one, -one, one, one, };

    int colors[] = { 0, 0, 0, one, one, 0, 0, one, one, one, 0, one, 0,
        one, 0, one, 0, 0, one, one, one, 0, one, one, one, one, one,
        one, 0, one, one, one, };

    byte indices[] = { 0, 4, 5, 0, 5, 1, 1, 5, 6, 1, 6, 2, 2, 6, 7, 2, 7,
        3, 3, 7, 4, 3, 4, 0, 4, 7, 6, 4, 6, 5, 3, 0, 1, 3, 1, 2 };

    // Buffers to be passed to gl*Pointer() functions
    // must be direct, i.e., they must be placed on the
    // native heap where the garbage collector cannot
    // move them.
    //
    // Buffers with multi-byte datatypes (e.g., short, int, float)
    // must have their byte order set to native order

    ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4);
    vbb.order(ByteOrder.nativeOrder());
    mVertexBuffer = vbb.asIntBuffer();
    mVertexBuffer.put(vertices);
    mVertexBuffer.position(0);

    ByteBuffer cbb = ByteBuffer.allocateDirect(colors.length * 4);
    cbb.order(ByteOrder.nativeOrder());
    mColorBuffer = cbb.asIntBuffer();
    mColorBuffer.put(colors);
    mColorBuffer.position(0);

    mIndexBuffer = ByteBuffer.allocateDirect(indices.length);
    mIndexBuffer.put(indices);
    mIndexBuffer.position(0);
  }

  public void draw(GL10 gl) {
    gl.glFrontFace(GL10.GL_CW);
    gl.glVertexPointer(3, GL10.GL_FIXED, 0, mVertexBuffer);
    gl.glColorPointer(4, GL10.GL_FIXED, 0, mColorBuffer);
    gl.glDrawElements(GL10.GL_TRIANGLES, 36, GL10.GL_UNSIGNED_BYTE,
        mIndexBuffer);
  }

  private IntBuffer mVertexBuffer;
  private IntBuffer mColorBuffer;
  private ByteBuffer mIndexBuffer;
}

/**
 * Implement a simple rotation control.
 * 
 */
class TouchSurfaceView extends GLSurfaceView {

  public TouchSurfaceView(Context context) {
    super(context);
    mRenderer = new CubeRenderer();
    setRenderer(mRenderer);
    setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
  }

  @Override
  public boolean onTrackballEvent(MotionEvent e) {
    mRenderer.mAngleX += e.getX() * TRACKBALL_SCALE_FACTOR;
    mRenderer.mAngleY += e.getY() * TRACKBALL_SCALE_FACTOR;
    requestRender();
    return true;
  }

  @Override
  public boolean onTouchEvent(MotionEvent e) {
    float x = e.getX();
    float y = e.getY();
    switch (e.getAction()) {
    case MotionEvent.ACTION_MOVE:
      float dx = x - mPreviousX;
      float dy = y - mPreviousY;
      mRenderer.mAngleX += dx * TOUCH_SCALE_FACTOR;
      mRenderer.mAngleY += dy * TOUCH_SCALE_FACTOR;
      requestRender();
    }
    mPreviousX = x;
    mPreviousY = y;
    return true;
  }

  /**
   * Render a cube.
   */
  private class CubeRenderer implements GLSurfaceView.Renderer {
    public CubeRenderer() {
      mCube = new Cube();
    }

    public void onDrawFrame(GL10 gl) {
      /*
       * Usually, the first thing one might want to do is to clear the
       * screen. The most efficient way of doing this is to use glClear().
       */

      gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

      /*
       * Now we're ready to draw some 3D objects
       */

      gl.glMatrixMode(GL10.GL_MODELVIEW);
      gl.glLoadIdentity();
      gl.glTranslatef(0, 0, -3.0f);
      gl.glRotatef(mAngleX, 0, 1, 0);
      gl.glRotatef(mAngleY, 1, 0, 0);

      gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
      gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

      mCube.draw(gl);
    }

    public void onSurfaceChanged(GL10 gl, int width, int height) {
      gl.glViewport(0, 0, width, height);

      /*
       * Set our projection matrix. This doesn't have to be done each time
       * we draw, but usually a new projection needs to be set when the
       * viewport is resized.
       */

      float ratio = (float) width / height;
      gl.glMatrixMode(GL10.GL_PROJECTION);
      gl.glLoadIdentity();
      gl.glFrustumf(-ratio, ratio, -1, 1, 1, 10);
    }

    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
      /*
       * By default, OpenGL enables features that improve quality but
       * reduce performance. One might want to tweak that especially on
       * software renderer.
       */
      gl.glDisable(GL10.GL_DITHER);

      /*
       * Some one-time OpenGL initialization can be made here probably
       * based on features of this particular context
       */
      gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST);

      gl.glClearColor(1, 1, 1, 1);
      gl.glEnable(GL10.GL_CULL_FACE);
      gl.glShadeModel(GL10.GL_SMOOTH);
      gl.glEnable(GL10.GL_DEPTH_TEST);
    }

    private Cube mCube;
    public float mAngleX;
    public float mAngleY;
  }

  private final float TOUCH_SCALE_FACTOR = 180.0f / 320;
  private final float TRACKBALL_SCALE_FACTOR = 36.0f;
  private CubeRenderer mRenderer;
  private float mPreviousX;
  private float mPreviousY;
}

   
    
    
  

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