Draw a JPEG

OpenGL Development JOGL Development
#1

Hi all.

How can i use jogl to draw something and than, instead of display the result on a monitor, encode it to a jpeg ?

#2

Here is how I save a canvas in jogl to jpeg.


public void saveImage() {
        try {
            saveDialog saveObj = new saveDialog();
            String str;  //string the will be the filename saved as
            GraphicsConfiguration gc = saveArea.getGraphicsConfiguration();
            //created buffered image of dimension same as plot to be saved
            BufferedImage bimg = gc.createCompatibleImage(saveArea.getWidth(), saveArea.getHeight());
            saveArea.paint(bimg.getGraphics()); //puts canvas into buffered image
            
            //used to set str to string to be saved as
            //the parameter 0 tells saveDialog XYPlot is being saved
            str = saveObj.getFilename(0);
            if (str != "null") {
                File imageFile = new File(str);//here come up with own filename
                ImageIO.write(bimg, "jpg", imageFile); //saves files
            }
        } catch (IOException ie) {
            System.err.println("can't write jpg file");
        }

please note saveArea is what is being saved and it is a GLJPanel.

#3

Thanks a lot!!

Another little question, if i’m under linux, to use JOGL i must have an x-session started ?

#4

[quote]Another little question, if i’m under linux, to use JOGL i must have an x-session started ?
[/quote]
Yes, at least currently. If you want to have almost-pure offscreen rendering, you can make a tiny borderless onscreen window, create a pbuffer from it, close the window, and use the pbuffer from then on.

#5

Ok thanks,

but actually i don’t know what a pbuffer is, can you explain ?

#6

[quote]Here is how I save a canvas in jogl to jpeg.

please note saveArea is what is being saved and it is a GLJPanel.
[/quote]
I’m using a GLCanvas instead of GLJPanel


GraphicsConfiguration gc = canvas.getGraphicsConfiguration();
            
            //created buffered image of dimension same as plot to be saved
            BufferedImage bimg = gc.createCompatibleImage(500, 500);
            canvas.paint(bimg.getGraphics());
            
            try {
                  File imageFile = new File("C:\\test.png");
                  ImageIO.write(bimg, "png", imageFile);
            } catch (IOException e) {
                  e.printStackTrace();
            }

and the only result is a black square…
i’ve miss something?

#7

Take a look at the links in this bug report for a couple of examples of taking screenshots and printing. The source code for the GLJPanel also shows how to read back the OpenGL frame buffer into a BufferedImage which you can then save using ImageIO.

#8

[quote]Take a look at the links in this bug report for a couple of examples of taking screenshots and printing. The source code for the GLJPanel also shows how to read back the OpenGL frame buffer into a BufferedImage which you can then save using ImageIO.
[/quote]
Yes yes yes !! I’ve found what i need, thanks!!