Posted by tinker on Aug 27, 2017; 9:29am
URL: https://forum.jogamp.org/Objects-randomly-not-rendering-on-OffScreen-Canvas-tp4038163.html

I'm writing an application that uses Java3D to do rendering of snapshot stills of its state, in other words doesn't have a live a object graph that renders on the screen. For every snapshot requested the application builds up a new Canvas, new SimpleUniverse and creates a new object graph and triggers a render. So far, so good. But randomly some or all objects do not render in what appears to be some sort of race condition. A scene that renders perfectly once may be completely empty when re-rendered later, although the scene contents and input is exactly the same. The background, which is a solid color, always appears to render, though. The problem seems to occur more often when there is a larger number of objects in the graph. Any advice or tips or theories on how to deal with this would be greatly appreciated. This is the implementation of my OffScreenCanvas:

public class OffScreenCanvas3D extends Canvas3D {

  public OffScreenCanvas3D(GraphicsConfiguration config) {
    super(config, true);
  }
  
  BufferedImage doRender(int width, int height) {    
    BufferedImage bImage = new BufferedImage(width, 
                                             height,
                                             BufferedImage.TYPE_INT_ARGB);    

    ImageComponent2D buffer = new ImageComponent2D(ImageComponent.FORMAT_RGBA, 
                                                   bImage);
    setOffScreenBuffer(buffer);

    Screen3D virtualScreen = getScreen3D();
    virtualScreen.setSize(new Dimension(width, height));

    virtualScreen.setPhysicalScreenWidth(0.0254/90.0 * width);
    virtualScreen.setPhysicalScreenHeight(0.0254/90.0 * height);    
    
    renderOffScreenBuffer();
    waitForOffScreenRendering();

    return getOffScreenBuffer().getImage();
  }

}

Basically, the object graph is built and then the doRender method is called to return a BufferedImage.