CODEWITHSUNDEEP
c++opengltexturesantialiasingpost-processing
Predrag Manojlovic
Predrag Manojlovic

Reputation: 378

OpenGL Anti aliasing of shapes on texture after it is created

I have a transparent OpenGL texture which has some simple shapes drawn on it by OpenGL: circles, polygons, lines. They are drawn without anti-aliasing, multi-sampling, etc. Therefore, they have jaggy borders.

I don't have access to process of texture creation so I cannot enable multi-sampling . Is there a way to make those smooth AFTER drawing is done?

Upvotes: 0

Views: 775

Answers (1)

Andon M. Coleman
Andon M. Coleman

Reputation: 43359

There are image-based anti-aliasing filters such as FXAA and MLAA that will work in this situation. I hesitate to call them anti-aliasing because they do not really avoid aliasing, they just hide it after the fact. They are more akin to intelligent blur filters.

I know from your other question that you do not want to use FBOs, so that leads me to believe you are using an OpenGL 2.1 or older codebase. FXAA can be implemented in GLSL 1.20, but it works better in 1.30 (GL 3.0). The one thing I do not know about is using FXAA on an image that includes transparency, it expects luminance to be encoded in the alpha channel (or sRGB, which is not a GL 2.1 feature).

You will probably not want to apply FXAA to your texture directly, rather you would need to draw into a PBuffer and apply FXAA after you blend your input texture.

Upvotes: 2

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