CODEWITHSUNDEEP
openglsmoothing
Phito
Phito

Reputation: 23

POLYGON_SMOOTH in OpenGL doing wierd things

I am trying to get some anti aliasing in my voxel engine, but when I enable the GL_POLYGON_SMOOTH state, I get these weird waves on the border of the polygons

Without:

  

With:

  

Do you have an idea from where this could be from?

Upvotes: 1

Views: 371

Answers (1)

Andon M. Coleman
Andon M. Coleman

Reputation: 43379

That is normal.

You need 3 things for polygon smoothing to work properly:

  1. Draw your voxels from back-to-front when you use GL_POLYGON_SMOOTH.
  2. A framebuffer that stores destination alpha (e.g. RGBA not RGB)
  3. The blend function needs to be GL_SRC_ALPHA_SATURATE, GL_ONE

If you account for all three of those things, the black and white subpixel artifacts will go away.

Since drawing the voxels in a specific order is rather tedious and GL_POLYGON_SMOOTH is deprecated, most people simply use Multisample Anti-Aliasing instead. I would actually suggest you also go that route.

Upvotes: 3

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