Android 2D/3D Graphics - OpenGL Tutorials

Android 2D/3D Graphics - OpenGL Tutorials :: New Project - Looking for ideas

arachnospore — Mon, 09 Nov 2009 18:53:16 GMT

Author: arachnospore
Subject: New Project - Looking for ideas
Posted: Mon Nov 09, 2009 7:53 pm (GMT 1)

Hi guys,

I'm new to the site and reasonably new to android but I've been coding for a while now. I'm starting a project to create a 3D space and load images into this space where the user will have the ability to "fly" around them. This will lead onto more complex things but this is my starting point. I'm completely new to OpenGL so I'm looking for pointers and tips on where to start.

Cheers in advance
_________________
Put on some golf shoes man or we'll never leave this place alive!

Android 2D/3D Graphics - OpenGL Tutorials :: GlDrawElements and drawing a quad

Shaka — Sun, 08 Nov 2009 16:18:37 GMT

Author: Shaka
Subject: GlDrawElements and drawing a quad
Posted: Sun Nov 08, 2009 5:18 pm (GMT 1)

Hi!

I've been trying to draw a simple quad with OpenGL ES the entire day today without success. I'm using this for my 2D "engine" and want to draw it in orthographic projection. I've managed to do it with glDrawArrays but not with glDrawElements. Maybe some of you guys can see what I'm doing wrong.

Here's the code for my quad.

Java:

public class OpenGLSprite {        

     public IntBuffer VertexBuffer;

     public IntBuffer ColorBuffer;

     public ByteBuffer IndexBuffer;     

     private int one = 0x10000;

    int vertices[] = {

            -one, -one, one, 

            one, -one, one,

            -one, one, one, 

            one, one, one

    };

    int colors[] = {

         one,    one,    one,  one,

         one,    one,    one,  one,

         one,    one,    one,  one,

         one,    one,    one,  one,      

    };

    byte indices[] = {

          0, 1, 2, 1, 2, 3

    };

    public OpenGLSprite(){      

          ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length*4);

          vbb.order(ByteOrder.nativeOrder());

          VertexBuffer = vbb.asIntBuffer();

          VertexBuffer.put(vertices);

          VertexBuffer.position(0);

          ByteBuffer cbb = ByteBuffer.allocateDirect(colors.length*4);

          cbb.order(ByteOrder.nativeOrder());

          ColorBuffer = cbb.asIntBuffer();

          ColorBuffer.put(colors);

          ColorBuffer.position(0);

          IndexBuffer = ByteBuffer.allocateDirect(indices.length);

          IndexBuffer.put(indices);

          IndexBuffer.position(0);           

    }

}

And here's the drawing code: oglSprite is a OpenGLSprite instance.

Java:

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

gl.glMatrixMode(GL10.GL_PROJECTION);

gl.glLoadIdentity();     

GLU.gluOrtho2D(gl, 0.0f, _width, 0.0f, _height);

gl.glMatrixMode(GL10.GL_MODELVIEW);        

gl.glLoadIdentity();

GLU.gluLookAt(gl, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);

gl.glVertexPointer(3, GL10.GL_FIXED, 0, oglSprite.VertexBuffer);

gl.glColorPointer(4, GL10.GL_FIXED, 0, oglSprite.ColorBuffer);            

gl.glDrawElements(GL10.GL_TRIANGLES, 6, GL10.GL_UNSIGNED_BYTE, oglSprite.IndexBuffer);

I've initialized with this code below:

Java:

          gl.glClearColor(0.0f, 0.0f, 1.0f, 0.0f);

     gl.glEnable(GL10.GL_TEXTURE_2D);

     gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

     gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);

     gl.glEnableClientState(GL10.GL_NORMAL_ARRAY);

My brain is really hurting at this point so any suggestions are appreciated.

Regards/Per

Android 2D/3D Graphics - OpenGL Tutorials :: Known issues with HTC hero 1.5 fw and OpenGL ES ?

Skywhy — Sun, 08 Nov 2009 13:19:18 GMT

Author: Skywhy
Subject: Known issues with HTC hero 1.5 fw and OpenGL ES ?
Posted: Sun Nov 08, 2009 2:19 pm (GMT 1)

Yeah, I'm kind of having interesting problems with my current openGL game. It runs perfectly fine on 1.6 and 1.5 emulators but when I upload it into my htc hero 1.5 it nothing appears. Well the game does start, it does clear the screen colours to what it should be but when I try to render to screen using normal vertex and index buffers via glVertexPointer() and glDrawElements() absolutely nothing appears on the screen.

It does the gl.glClearScreen() and clears the screen to set colour but no given vertices are rendered. Any ideas what is going on? It's mighty confusing if nothing else. I went through it with the debugger and it goes to the rendering thread, performs the operations and such but nothing just appears and it works perfectly fine on different versions on the emulator.

Is there something I'm completely missing now, or?

Android 2D/3D Graphics - OpenGL Tutorials :: how to create this menu?

newbin — Sun, 08 Nov 2009 01:28:07 GMT

Author: newbin
Subject: how to create this menu?
Posted: Sun Nov 08, 2009 2:28 am (GMT 1)

like this picture:

thanks all.

Android 2D/3D Graphics - OpenGL Tutorials :: GLU.gluOrtho2D, frustum culling and "picking"(?).

Skywhy — Fri, 06 Nov 2009 18:17:03 GMT

Author: Skywhy
Subject: GLU.gluOrtho2D, frustum culling and "picking"(?).
Posted: Fri Nov 06, 2009 7:17 pm (GMT 1)

Hey guys!

I've been busy working on my game for Android but there are few things I'm still a bit feeling "wonky" over. Can I get the android screen pixels to match the world coordinates? I'm guessing not, never thought of this really.

But my main question is, since I'm doing a 2D game, how should I perform frustum culling for objects in my 2D game? Obviously I don't want to to render objects that are WAY off the screen

Also, what about "picking"? Since I'm going to do a game where place stuff into the game world by pressing the touch screen I guess I need to do some sort of conversion from screen coordinates to the actual world coordinates that OpenGL ES uses. How is this done?

Basically what I'm after I want to slam an object in the world on to the exact spot the user just pressed on Also if it matters at all I'm using the Glu.gluOrtho2D() method to produce my orthogonal view of the game world.

Cheers!

EDIT #1:
or does calling GLU.gluOrtho2D() already match the world coordinates to screen coordinates if I give it the screen W and H? If so, I can then easily just use screen coordinates to say that "place this item here", right? But if no then I need to do the screen space to world space conversion.

So easiest for me probably would be to able to match screen coordinates to openGL world coordinates. Any ideas?

// SkyWhy

Android 2D/3D Graphics - OpenGL Tutorials :: Flood of touch events fixed?

Kyros — Tue, 03 Nov 2009 15:05:50 GMT

Author: Kyros
Subject: Flood of touch events fixed?
Posted: Tue Nov 03, 2009 4:05 pm (GMT 1)

Hi all,

While using a GLSurfaceView and onTouchEvent I used to get a flood of events when touching the screen.
This resulted in me needed to sleep this otherwise it affected framerate.

I noticed recently it doesnt do this anymore.
I was wondering if this flooding was a bug that is now fixed or whether it can be switched on or off now?

The reason I ask is that both could be useful to have.
Object selection might be one use without flooding but dragging an object would need a flood of events.

Android 2D/3D Graphics - OpenGL Tutorials :: User presses Home or Back

jbrohan — Mon, 02 Nov 2009 18:22:10 GMT

Author: jbrohan
Subject: User presses Home or Back
Posted: Mon Nov 02, 2009 7:22 pm (GMT 1)

Hello
I'm dealing with un-sophisticated users and I want the result to be the same whether he presses Home or Back. If I can find out that he pressed Home last time, or the job was swapped out then I can close some resources like the camera and start again at the onCreate.

The app starts off in Camera Preview and goes through a take picture and send in picture steps. it's awkward to re-start it, and most likely the user will be most comfortable if it starts always in the same place.

Any ideas or suggestions on how to achieve this. Taking over the Home key does not seem like an option!
John

Android 2D/3D Graphics - OpenGL Tutorials :: Android manifest file

usha — Fri, 30 Oct 2009 07:10:40 GMT

Author: usha
Subject: Android manifest file
Posted: Fri Oct 30, 2009 8:10 am (GMT 1)

what is the use of Manifest file in android...............