Android example source code file (TouchRotateActivity.java)

This example Android source code file (TouchRotateActivity.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

activity, android, app, content, cuberenderer, eglconfig, glsurfaceview, opengl, os, override, touch_scale_factor, touchrotateactivity, touchsurfaceview, trackball_scale_factor, view

The TouchRotateActivity.java Android example source code

/*
 * 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 com.example.android.apis.graphics;

import javax.microedition.khronos.egl.EGL10;
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 TouchRotateActivity 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;
}

/**
 * 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;
}