public void updatePixels() {
    // flip vertically (opengl stores images upside down),

    int index = 0;
    int yindex = (height - 1) * width;
    for (int y = 0; y < height/2; y++) {
	if (BIG_ENDIAN) {
	  // and convert ARGB back to opengl RGBA components (big endian)
	  for (int x = 0; x < width; x++) {
	    int temp = pixels[index];
	    /*
		pixels[index] =
		((pixels[yindex] >> 24) & 0xff) |
		((pixels[yindex] << 8) & 0xffffff00);
	    pixels[yindex] =
		((temp >> 24) & 0xff) |
		((temp << 8) & 0xffffff00);
	    */
	    pixels[index] = ((pixels[yindex] << 8) & 0xffffff00) | 0xff;
	    pixels[yindex] = ((temp << 8) & 0xffffff00) | 0xff;

	    index++;
	    yindex++;
	  }

	} else {
	  // convert ARGB back to native little endian ABGR
	  for (int x = 0; x < width; x++) {
	    int temp = pixels[index];

	    pixels[index] = 0xff000000 |
		((pixels[yindex] << 16) & 0xff0000) |
		(pixels[yindex] & 0xff00) |
		((pixels[yindex] >> 16) & 0xff);

	    pixels[yindex] = 0xff000000 |
		((temp << 16) & 0xff0000) |
		(temp & 0xff00) |
		((temp >> 16) & 0xff);

	    index++;
	    yindex++;
	  }
	}
	yindex -= width*2;
    }

    // re-pack ARGB data into RGBA for opengl (big endian)
    /*
    for (int i = 0; i < pixels.length; i++) {
	pixels[i] = ((pixels[i] >> 24) & 0xff) |
	  ((pixels[i] << 8) & 0xffffff00);
    }
    */

    //System.out.println("running glDrawPixels");
    //gl.glRasterPos2i(width/2, height/2);
    //gl.glRasterPos2i(width/2, 1); //height/3);
    //gl.glRasterPos2i(1, height - 1); //1, 1);

    // for some reason, glRasterPos(0, height) won't draw anything.
    // my guess is that it's getting "clipped", so adding an epsilon
    // makes it work. also, height-1 would be the logical start,
    // but apparently that's not how opengl coordinates work
    gl.glRasterPos2f(0.0001f, height - 0.0001f);

    gl.glDrawPixels(width, height, GL.GL_RGBA, GL.GL_UNSIGNED_BYTE, pixels);
  }