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Editorial Team
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Asked: 2026-05-26T21:45:51+00:00

I’m currently using OpenGL on Android to draw set width lines, which work great

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I’m currently using OpenGL on Android to draw set width lines, which work great except for the fact that OpenGL on Android does not natively support the anti-aliasing of such lines. I have done some research, however I’m stuck on how to implement my own AA.

FSAA

The first possible solution I have found is Full Screen Anti-Aliasing. I have read this page on the subject but I’m struggling to understand how I could implement it.

  • First of all, I’m unsure on the entire concept of implementing FSAA here. The article states “One straightforward jittering method is to modify the projection matrix, adding small translations in x and y”. Does this mean I need to be constantly moving the same line extremely quickly, or drawing the same line multiple times?
  • Secondly, the article says “To compute a jitter offset in terms of pixels, divide the jitter amount by the dimension of the object coordinate scene, then multiply by the appropriate viewport dimension”. What’s the difference between the dimension of the object coordinate scene and the viewport dimension? (I’m using a 800 x 480 resolution)

Now, based on the information given in that article the ‘jitter’ coordinates should be relatively easy to compute. Based on my assumptions so far, here is what I have come up with (Java)…

float currentX = 50;
float currentY = 75;

// I'm assuming the "jitter" amount is essentially
// the amount of anti-aliasing (e.g 2x, 4x and so on)
int jitterAmount = 2;

// don't know what these two are
int coordSceneDimensionX;
int coordSceneDimensionY;

// I assume screen size
int viewportX = 800;
int viewportY = 480;

float newX = (jitterAmount/coordSceneDimensionX)/viewportX;
float newY = (jitterAmount/coordSceneDimensionY)/viewportY;

// and then I don't know what to do with these new coordinates

That’s as far as I’ve got with FSAA

Anti-Aliasing with textures

In the same document I was referencing for FSAA, there is also a page that briefly discusses implementing anti-aliasing with the use of textures. However, I don’t know what the best way to go about implementing AA in this way would be and whether it would be more efficient than FSAA.

Hopefully someone out there knows a lot more about Anti-Aliasing than I do and can help me achieve this. Much appreciated!

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1 Answer

  1. Editorial Team

    The method presented in the articles predates the time, when GPUs were capable of performing antialiasing themself. This jittered rendering to a accumulation buffer is not really state of the art with realtime graphics (it is a widely implemented form of antialiasing for offline rendering though).

    What you do these days is requesting an antialiased framebuffer. That’s it. The keyword here is multisampling. See this SO answer:
    How do you activate multisampling in OpenGL ES on the iPhone? – although written for the iOS, doing it for Android follows a similar path. AFAIK On Android this extension is used instead http://www.khronos.org/registry/gles/extensions/ANGLE/ANGLE_framebuffer_multisample.txt

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