Sample Code for Open GL in Android

Sample Code for Open GL in Android

Now your basic Open GL ES concepts are clear as written in the previous post (http://creativeandroidapps.blogspot.in/2012/07/basics-of-opengl-in-android.html) you are ready to create something with OpenGL on Android in your creative application.


This post is explaining a very popular sample for the Open GL for the new developers to quickly understand the implementation of Open GL functions and classes. For a basic Open GL project you need to create a activity class where you host your GLSurfaceView. The render something on the view we need to implement the GLSurfaceView.Renderer interface.


See here the code of my sample class.

Create a Activity Class

package com.example.sampleopengl;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;


public class MainActivity extends Activity {

    private MyGLSurfaceView mGLView;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mGLView = new MyGLSurfaceView(this,null);
        setContentView(mGLView);
        
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    
}

See the highlighted code which you need to add in your activity class after implementing the following two classes.


Now create a class named MyGLSurfaceView which extends the GLSurfaceView to set as the view of activity.

package com.example.sampleopengl;

import android.content.Context;
import android.opengl.GLSurfaceView;
import android.util.AttributeSet;
import android.view.MotionEvent;

public class MyGLSurfaceView extends GLSurfaceView {

    MyGLRenderer mRenderer;
    public MyGLSurfaceView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        mRenderer = new MyGLRenderer();
        setRenderer(mRenderer);
    }
    //change the color on touch
    public boolean onTouchEvent(final MotionEvent event) {
        queueEvent(new Runnable(){
            public void run() {
                mRenderer.setColor(event.getX() / getWidth(),
                        event.getY() / getHeight(), 1.0f);
            }});
            return true;
        }

}

See the implementation of the Renderer which will render the color.

package com.example.sampleopengl;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.opengl.GLSurfaceView;

public class MyGLRenderer implements GLSurfaceView.Renderer {
    private float mRed;
    private float mGreen;
    private float mBlue;
    
      public void setColor(float r, float g, float b) {
        mRed = r;
        mGreen = g;
        mBlue = b;
    }

    @Override  //function draw the opengl graphics
    public void onDrawFrame(GL10 gl) {
        // TODO Auto-generated method stub
         gl.glClearColor(mRed, mGreen, mBlue, 1.0f);
         gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
        
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int w, int h) {
        // TODO Auto-generated method stub
        gl.glViewport(0, 0, w, h);
        
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig arg1) {
        // TODO Auto-generated method stub
        
        
    }


}

Now you can run the sample code and see the following result as your first sample of Open GL on android.

Open GL - Color 1

On touch you will see a color change on the Open GL surface view created in activity.

Open GL - Color 2

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Thanks
Creative Android Apps