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Chuckles_UK
Journeyman III

Sprites rendered with Alpha Test On do not render if Multisampling

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Hi,

I've got a bug where rendering sprites with alpha testing (but no alpha-blending) doesn't appear to work when rendering to an anti-aliased frame buffer.  I'm using OpenGL and the card in question is an HD5670, but this may apply to other cards too.  The same code works fine on a number of other (non-ATI) graphics cards, so I'm guessing the problem is either:

  1. A bug in the ATI driver
  2. A 'feature' of OpenGL that is supported differently by different platforms - the documentation surrounding the use of Framebuffers and the reporting of errors seems to be sadly lacking.

Does anybody have any suggestions?

Cheers,

Charles

Charles Blessing

Senior Programmer

Team17 Software Ltd.

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1 Solution

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gsellers
Staff
Staff

Re: Sprites rendered with Alpha Test On do not render if Multisampling

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Hi Charles,

We reproduced the problem on older drivers, but found that it was already fixed a couple of months ago by one of my engineers. The change has already made the regular Catalyst posting. If your users update their drivers to the most recent release (12.2 at time of writing), you should find that the issue is resolved.

Let me know if you have any other issues.

Cheers,

Graham

View solution in original post

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4 Replies
gsellers
Staff
Staff

Re: Sprites rendered with Alpha Test On do not render if Multisampling

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Hi Charles,

Alpha testing and MSAA should be orthogonal. Keep in mind that this depends on what you're rendering and what your shaders do. Do you have a test case you can share, or is it simply enough to use alpha test + MSAA together to see the issue?

Cheers,

Graham

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Chuckles_UK
Journeyman III

Re: Sprites rendered with Alpha Test On do not render if Multisampling

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Hi Graham,

The game is currently released on Steam - I could get you a license key for it if that would be helpful?  Stripping out a simple test case could be tricky (although not impossible) if a key for the game doesn't help.

Cheers,

Charles

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gsellers
Staff
Staff

Re: Sprites rendered with Alpha Test On do not render if Multisampling

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Absolutely - a Steam key for the product is fine. You can email me directly at my<dot>name<at>amd.com.

Cheers,

Graham

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gsellers
Staff
Staff

Re: Sprites rendered with Alpha Test On do not render if Multisampling

Jump to solution

Hi Charles,

We reproduced the problem on older drivers, but found that it was already fixed a couple of months ago by one of my engineers. The change has already made the regular Catalyst posting. If your users update their drivers to the most recent release (12.2 at time of writing), you should find that the issue is resolved.

Let me know if you have any other issues.

Cheers,

Graham

View solution in original post

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