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Touch Rotate Example in Android


Posted by Sushant on July 6, 2012, filed in: Android Beginner Tutorials, Android Development

This example shows how you can create touch and rotate effect on an object.

Algorithm:

1.) Create a new project by File-> New -> Android Project name it TouchRotateExample.

2.) Create and write following into src/cube.java file:

package com.example.TouchRotateExample;
import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.IntBuffer;
import javax.microedition.khronos.opengles.GL10;
class Cube
 {
     public Cube()
     {
         int one = 0×10000;
         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
         };
        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;
 }

3.) Run for output.

Steps:

1.) Create a project named TouchRotateExample and set the information as stated in the image.

Build Target: Android 4.0
Application Name: TouchRotateExample
Package Name: com. example. TouchRotateExample
Activity Name: TouchRotateExample
Min SDK Version: 14

2.) Open TouchRotateExample.java file and write following code there:

package com.example.TouchRotateExample;

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;
public class TouchRotateExample extends Activity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
        mGLSurfaceView = new TouchSurfaceView(this);
         setContentView(mGLSurfaceView);
         mGLSurfaceView.requestFocus();
         mGLSurfaceView.setFocusableInTouchMode(true);
     }
    @Override
     protected void onResume() {
         super.onResume();
         mGLSurfaceView.onResume();
     }
    @Override
     protected void onPause() {
         super.onPause();
         mGLSurfaceView.onPause();
     }
    private GLSurfaceView mGLSurfaceView;
 }
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;
     }
     private class CubeRenderer implements GLSurfaceView.Renderer {
         public CubeRenderer() {
             mCube = new Cube();
         }
        public void onDrawFrame(GL10 gl) {
             gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
             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);
             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) {
             gl.glDisable(GL10.GL_DITHER);
              gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,
                      GL10.GL_FASTEST);
             gl.glClearColor(0,0,0,0);
              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;
 }

3.) Compile and build the project.

Output

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One comment on “Touch Rotate Example in Android

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