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So, I was annoyed by how the HUD for my GameState was very pixel-ated and I wanted to change that through the use of anti-aliasing. However, it works with a small exception: enter image description here

It adds all these lines to the HUD, which is not what I want at all, is there a way to prevent this from occurring?

Here's what it looked like before anti-aliasing:

enter image description here

Also, here's the code:

    public void render(GameContainer container, StateBasedGame game, Graphics graphics) throws SlickException {
    graphics.setAntiAlias(true);
    renderOverlayGui(graphics);
    renderGui(graphics);
    graphics.setAntiAlias(false);
    renderIcons(graphics);
}

private void renderIcons (Graphics graphics) {
    graphics.drawImage(imgHeart, this.radius - 4, 1);
    graphics.drawImage(imgCoolDown, this.radius - 4, 18);
}

private void renderGui (Graphics graphics) {
    graphics.setColor(GameColour.brown);
    graphics.fill(guiCircle);
    graphics.fill(guiBox);
}

private void renderOverlayGui (Graphics graphics) {
    graphics.setColor(Color.black);
    graphics.fill(guiOverlayCircle);
    graphics.fill(guiOverlayBox);
}
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It looks like the edges get a fractional alpha based on the edge coverage. Problem arises when two edges fill 100% together but are blended as translucency, not coverage, only applying ~75% color. It's like the difference between covering your eyes with both hands vs covering your eyes with two pair of sunglasses.

I only know how this works in opengl, but basically the technique requires you to render front to back order, no depth buffering, having alpha channel in destination framebuffer and set a special blending function (glBlendFunc(GL_SRC_ALPHA_SATURATE,GL_ONE)).

I don't know much about slick, but you could start out checking if you have an alpha channel in your framebuffer/window. Slick just might do the rest for you. I'll check out the library more closely when I have the chance.

Edit When looking closer at the slick source code (Graphics.java) it appears not being able to anti-alias triangle meshes without artifacts. It does appear possible to fix the source. I'll look into it.

Until then it might be best to draw textures instead that are anti-aliased from the beginning using GIMP or similar tool.

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  • \$\begingroup\$ Problem is is that I just used the graphics.setAntiAlias(); in the hopes it would only render the circles better. I essentially have no clue to what you are trying to say nor how the rendering is suppose to be done :( (I don't know much about graphics-programming). If you could explain a bit more in depth, it will probably help a little more. Thanks! \$\endgroup\$ – BlueJet May 3 '16 at 19:15
  • \$\begingroup\$ @BlueJet I have read the slick source code. It does not look to good. Seems like anti-aliasing of meshes such as circles is not implemented at all (or incorrectly depending how you see it). It only works for lone triangles and line meshes. I could rewrite the source for you... What do want me to do? \$\endgroup\$ – Andreas May 3 '16 at 20:13
  • \$\begingroup\$ By "source", do you possibly mean re-writing the Graphics.java anti-aliasing source code? I went through the source code as well and upon inspection the anti-aliasing that the Graphics class isn't really the best, but I can't really say since I've only been using Slick2D for a while now. If you could redo the "source" and publish the source-code in an edit to your post above, that would be beneficial to most people who are also having problems with anti-aliasing in Slick2D. But the question is if you actually want to redo the source (it will probably take some time looking at it). Thanks! \$\endgroup\$ – BlueJet May 3 '16 at 22:45
  • \$\begingroup\$ @BlueJet Exactly. I'll edit my post describing my findings. If I get the time I will try to fix the source and post it here. Gotta setup dev env for slick and java as well as making a test application. It might take while. \$\endgroup\$ – Andreas May 4 '16 at 5:10
  • \$\begingroup\$ Alright, thanks for helping out and I look forward to your findings. \$\endgroup\$ – BlueJet May 4 '16 at 22:41

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