### Author:  [@mbbl33](https://discourse.processing.org/u/mbbl33)
#### Post date: [January 6, 2023, 8:39am UTC](https://discourse.processing.org/t/use-3d-graphics-on-android-for-draw-an-obj-file-offscreen/40483/1 "2023-01-06T08:39:24Z")
Hello all,
I am trying to draw an .obj file offscreen under Android.
The image should then be passed to OpenCV for further use as a matrix.
In 2D the whole thing already works without problems.
```java
public class ObjDrawer extends PApplet {
PGraphics buffer;
PShape obj;
int width;
int height;
public ObjDrawer(int width, int height) {
this.width = width;
this.height = height;
setup();
}
@Override
public void setup() {
buffer = createGraphics(this.width, this.height, P3D);
//obj = loadShape("Wuerfel_40mm.obj");
noLoop();
}
public Mat testDraw() {
buffer.beginDraw();
buffer.background(255);
buffer.ellipse(200, 200, 100, 100);
//buffer.shape(obj);
buffer.endDraw();
return toMat(buffer.get());
}
Mat toMat(PImage image) {
//source: https://gist.github.com/Spaxe/3543f0005e9f8f3c4dc5
int w = image.width;
int h = image.height;
Mat mat = new Mat(h, w, CvType.CV_8UC4);
byte[] data8 = new byte[w * h * 4];
int[] data32 = new int[w * h];
arrayCopy(image.pixels, data32);
ByteBuffer bBuf = ByteBuffer.allocate(w * h * 4);
IntBuffer iBuf = bBuf.asIntBuffer();
iBuf.put(data32);
bBuf.get(data8);
mat.put(0, 0, data8);
return mat;
}
}
```
When using 3D, I now get the following error message:
```auto
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean processing.core.PGraphics.isGL()' on a null object reference
at processing.core.PApplet.makeGraphics(PApplet.java:1584)
at processing.core.PApplet.createGraphics(PApplet.java:1568)
at Analyzer.ObjDrawer.setup(ObjDrawer.java:52)
at Analyzer.ObjDrawer.(ObjDrawer.java:45)
at com.quickbirdstudios.opencvexample.MainActivity$cvCameraViewListener$1.onCameraFrame(MainActivity.kt:75)
at org.opencv.android.CameraBridgeViewBase.deliverAndDrawFrame(CameraBridgeViewBase.java:392)
at org.opencv.android.JavaCameraView$CameraWorker.run(JavaCameraView.java:373)
at java.lang.Thread.run(Thread.java:920)
```
In my research I read about a3d, this is missing for me. Since all the stuff I found regarding a3d was about 10 years old: has anything changed in this regard or has it been replaced or do I need to include this separately?
I have included Processing as in the tutorial on [https://android.processing.org/tutorials/android\_studio/index.html](https://android.processing.org/tutorials/android_studio/index.html)
integrated. I use Android Mode for Processing 3 4.3.0, because the mode manager in Processing 4 is currently broken.
many thanks in advance!
---
### Author:  [@erkosone](https://discourse.processing.org/u/erkosone)
#### Post date: [January 6, 2023, 9:33pm UTC](https://discourse.processing.org/t/use-3d-graphics-on-android-for-draw-an-obj-file-offscreen/40483/2 "2023-01-06T21:33:55Z")
Update your Android\_mode to the latest version, you just have to open an Android project from the IDe and it will be downloaded automatically.
Here you have a project for you to open with your editor. It will automatically start downloading in android mode 😉
> **[sketch\_221222a.zip](https://www.dropbox.com/s/hgv4rsmm9kunwca/sketch_221222a.zip?dl=0)**
>
> Shared with Dropbox
---
### Author:  [@mbbl33](https://discourse.processing.org/u/mbbl33)
#### Post date: [January 7, 2023, 9:50am UTC](https://discourse.processing.org/t/use-3d-graphics-on-android-for-draw-an-obj-file-offscreen/40483/3 "2023-01-07T09:50:36Z")
Thanks already for the answer.
When I open it in Processing 3, no update starts. In the contribution manager, no update is shown there either.
When I try to open it in Processing 4, it just shows the error message that I should update my Android mode, and it switches back to Java mode.
Which version are we talking about? The one for Processing 4 4.5.0b2?
It is unfortunately grayed out in P3 due to incompatibility, and in P4 the contribution manager for the modes does not work.
Can I get the appropriate core.jar somewhere else?
---
### Author:  [@erkosone](https://discourse.processing.org/u/erkosone)
#### Post date: [January 7, 2023, 10:01pm UTC](https://discourse.processing.org/t/use-3d-graphics-on-android-for-draw-an-obj-file-offscreen/40483/4 "2023-01-07T22:01:36Z")
Solo tienes que tener una version limpia de processing 4 en tu PC, “hablo de windows”, entonces abre el proyecto que te pase y automaticamente te saldrá un dialogo para descargar el Android mode ultima version.
---
### Author:  [@mbbl33](https://discourse.processing.org/u/mbbl33)
#### Post date: [January 8, 2023, 9:48am UTC](https://discourse.processing.org/t/use-3d-graphics-on-android-for-draw-an-obj-file-offscreen/40483/5 "2023-01-08T09:48:38Z")
I managed to update, but still get the same error. Does createGraphics() need the size() method before? I tried size() once in the first line of setup() and also tried it in settings(), in both cases I get the error that it is not in setting().