How to render rounded shape perfectly?

Question

I'm having issues rendering rounded shape figures. I have a Texture with different images in it and I get this whale figure from it with TextureRegion but the stroke of it looks pixelated.

The original whale image is 357x721 px and the program scalate it up or down depending on the device.

And I use TextureFilter to Nearest but it doesn't solve problem as I thought it would.

Does someone knows a bit about this issue?

    texture = new Texture(Gdx.files.internal("texturepack_nuevo.png"));
    texture.setFilter(TextureFilter.Nearest, TextureFilter.Nearest);

    pilar = new TextureRegion(texture,591,0,357,721);

    whale_1 = new TextureRegion(texture,0,0,591,323);
    whale_1.flip(false, true);

    whale_2 = new TextureRegion(texture,0,323,591,323);
    whale_2.flip(false, true);

    whale_3 = new TextureRegion(texture,0,646,591,323);
    whale_3.flip(false, true);

    TextureRegion[] whales = {whale_1,whale_2,whale_3};
    whaleAnimation = new Animation(0.15f, whales);
    whaleAnimation.setPlayMode(Animation.PlayMode.LOOP_PINGPONG);

Answer 1

You can't render a rounded shape perfectly on a computer screen; a computer screen is composed of discrete cells (pixels) so some approximation is always going to happen. It's just a matter of hiding that approximation so the result is visually appealing enough.

Nearest texture filtering is generally not what you want to create the appearance of smooth curves, because it simply chooses a color based on the closest integer boundary of a texel. Linear filtering (TextureFilter.Linear in libgdx) is more akin to what you want, since it will interpolate between the surrounding integer-boundary texel coordinates to arrive at a color. This can remove harsh edges, but often has the result of overcompensating and making those edges "blurry," especially for uneven scale factors.

If adjusting the filter does not provide the results you want, you may want to look into some methods of anti-aliasing.

Answer 2

You might also be interested in using vectors graphics. Vectors graphics use mathematical functions to describe objects rather then normal pixels. As such vector graphics are always as good as they can be on a given screen no matter how much you zoom in or out. You can look here for a number of software programs to generate vector graphics, now not every programming language supports vector graphics but most do.