Posted by Martin on Aug 11, 2022; 6:18am
URL: https://forum.jogamp.org/Runtime-switch-bewteen-orthographic-and-perspective-projections-tp4041812p4041815.html

Hi,

The reason for this exception is that OpenGL is single threaded. The only thread from which the OpenGL context is available by default is the AWT Thread (since the canvas is rendered inside the AWT thread).

When you need an application to perform GL calls outside of the AWT Thread, you have to acquire before your method call and then release the GL context after your method call.

Despite you have a solution, here is my utility to make the GL context available to the current thread :


  public GL acquireGL() {
    return getCurrentGL(canvas);
  }

  public void releaseGL() {
    getCurrentContext(canvas).release();
  }

  /**
   * Get the current GL context of the canvas and make it current.
   *
   * This is usefull when needing to get a GL instance outside of the context of the
   * {@link GLEventListener}.
   */
  public GL getCurrentGL(ICanvas canvas) {
    GLContext context = getCurrentContext(canvas);
    context.makeCurrent();
    return context.getGL();
  }

  public GLContext getCurrentContext(ICanvas canvas) {
    GLAutoDrawable d = ((INativeCanvas) canvas).getDrawable();
    return d.getContext();
  }


I then

GL gl = acquireGL();

gl.glDoSomething();

releaseGL();