samples/ApiDemos/src/com/example/android/apis/os/RotationVectorDemo.java

/*
 * Copyright (C) 2007 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.os;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.opengl.GLSurfaceView;
import android.os.Bundle;

/**
 * Wrapper activity demonstrating the use of the new
 * {@link SensorEvent#values rotation vector sensor}
 * ({@link Sensor#TYPE_ROTATION_VECTOR TYPE_ROTATION_VECTOR}).
 * 
 * @see Sensor
 * @see SensorEvent
 * @see SensorManager
 * 
 */
public class RotationVectorDemo extends Activity {
    private GLSurfaceView mGLSurfaceView;
    private SensorManager mSensorManager;
    private MyRenderer mRenderer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Get an instance of the SensorManager
        mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);

        // Create our Preview view and set it as the content of our
        // Activity
        mRenderer = new MyRenderer();
        mGLSurfaceView = new GLSurfaceView(this);
        mGLSurfaceView.setRenderer(mRenderer);
        setContentView(mGLSurfaceView);
    }

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


    class MyRenderer implements GLSurfaceView.Renderer, SensorEventListener {
        private Cube mCube;
        private Sensor mRotationVectorSensor;
        private final float[] mRotationMatrix = new float[16];

        public MyRenderer() {
            // find the rotation-vector sensor
            mRotationVectorSensor = mSensorManager.getDefaultSensor(
                    Sensor.TYPE_ROTATION_VECTOR);

            mCube = new Cube();
            // initialize the rotation matrix to identity
            mRotationMatrix[ 0] = 1;
            mRotationMatrix[ 4] = 1;
            mRotationMatrix[ 8] = 1;
            mRotationMatrix[12] = 1;
        }

        public void start() {
            // enable our sensor when the activity is resumed, ask for
            // 10 ms updates.
            mSensorManager.registerListener(this, mRotationVectorSensor, 10000);
        }

        public void stop() {
            // make sure to turn our sensor off when the activity is paused
            mSensorManager.unregisterListener(this);
        }

        public void onSensorChanged(SensorEvent event) {
            // we received a sensor event. it is a good practice to check
            // that we received the proper event
            if (event.sensor.getType() == Sensor.TYPE_ROTATION_VECTOR) {
                // convert the rotation-vector to a 4x4 matrix. the matrix
                // is interpreted by Open GL as the inverse of the
                // rotation-vector, which is what we want.
                SensorManager.getRotationMatrixFromVector(
                        mRotationMatrix , event.values);
            }
        }

        public void onDrawFrame(GL10 gl) {
            // clear screen
            gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

            // set-up modelview matrix
            gl.glMatrixMode(GL10.GL_MODELVIEW);
            gl.glLoadIdentity();
            gl.glTranslatef(0, 0, -3.0f);
            gl.glMultMatrixf(mRotationMatrix, 0);

            // draw our object
            gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
            gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

            mCube.draw(gl);
        }

        public void onSurfaceChanged(GL10 gl, int width, int height) {
            // set view-port
            gl.glViewport(0, 0, width, height);
            // set projection matrix
            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) {
            // dither is enabled by default, we don't need it
            gl.glDisable(GL10.GL_DITHER);
            // clear screen in white
            gl.glClearColor(1,1,1,1);
        }

        class Cube {
            // initialize our cube
            private FloatBuffer mVertexBuffer;
            private FloatBuffer mColorBuffer;
            private ByteBuffer  mIndexBuffer;

            public Cube() {
                final float vertices[] = {
                        -1, -1, -1,		 1, -1, -1,
                         1,  1, -1,	    -1,  1, -1,
                        -1, -1,  1,      1, -1,  1,
                         1,  1,  1,     -1,  1,  1,
                };

                final float colors[] = {
                        0,  0,  0,  1,  1,  0,  0,  1,
                        1,  1,  0,  1,  0,  1,  0,  1,
                        0,  0,  1,  1,  1,  0,  1,  1,
                        1,  1,  1,  1,  0,  1,  1,  1,
                };

                final 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
                };

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

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

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

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

        public void onAccuracyChanged(Sensor sensor, int accuracy) {
        }
    }
}