Disable FSAA for some primitives each frame? (disable it temporarily)

Disable FSAA for some primitives each frame? (disable it temporarily)

• Scott Gunn

  And it works flawlessly
  
  device.SetRenderState(RenderStates.MultisampleAntiAlias, false);
  
  Thanks
  
  
  

• Renata Yasa Putra

  Yes you have to apply the offset to the position and let the texture coordinate’s unchanged.

  If you want to draw from pixel 0 to 4 you have to use -0,5 to 3,5 as positions if you have pretransformed vertices.

  
  
  

• Sonnet

  I've tested my gui system on some cards now, the renderstate seems to work on at least these cards: 6800, 6800GT, 6800Go, 5950, and Radeon 9800Pro. The cards are very similar but I haven't had any chance on others yet, and the radeon is the only card which has the capability.

  Anyway, I've made a screenshot comparsion image that is available here:

  http://img92.imageshack.us/img92/986/gui6qp.png

  The top row shows the result with 0.5f texel offset, the bottom row does not use this texel offset. The right column uses four samples multisampling (4x antialiasing).

  We clearly see that the topleft image is looking correct, in the bottomleft image the texcoords are clearly off by a pixel. We also see that when we enable multisampling the image is worse, less pixel correct so to speak. We see this most clearly with the thinnest font lines, however the multisampling effect is about the same for both the upper and the lower row.

  
  

• JeffCurrier

  Aha
  
  Maybe I should know this but I don't... What happens if I try to set that renderstate on a system that doesn't have that capability Does it crash, throw an exception or is it just ignored / set without any effect
  
  And to add to that question, I have a similar one. I guess all cards doesn't support anisotropic filtering, what happens if I set texture filtering to anisotropic on a system that doesn't have caps for it Does it crash, throw an exception or fall back to linear filtering
  
  

• TomAStraw

  I've done a gui system using triangles of TransformedVertices instead of using sprites. My font also uses this method and furthermore I've set it to point filtering and I'm making sure that I'm drawing for example 20x20 pixels from the texture to 20x20 pixels on the screen. That way I get "per pixel correctness" just as with sprites. Now this is much faster than sprites and not that I'm sure of it but I believe I can use shaders with this user interface system but I wouldn't be able to use shaders on sprites.
  
  However, this is very neat and pixel perfect. That way small fonts are made up of 1px thin lines, these lines and the pixel perfection in general gets screwed if I add antialiasing. Thats why I would like to disable AA for the user interface but still have it on the terrain in my game, e.g. And on my card atm, it works really good.
  
  I will try to find a friend with an older gfx-card that doesn't support this state and try what happens.
  
  

• SimpleBits

  I am not sure why the newer GeForce does not report this Caps if it work. Maybe it does not work always.

  I don’t know what’s going wrong with your GUI elements but my own GUI works the same way and it is still smooth as it should with any kind of AA enabled. Have you check that you use a half pixel offset on every screen coordinate This is a common Direct3D mistake which can make the GUI blurry.

  
  
  

• benwalker

  You should read this:

  Http://msdn.microsoft.com/library/en-us/directx9_c/Directly_Mapping_Texels_to_Pixels.asp frame=true

  You don't need to look for a old card. All cards based on nVidia chips does not support this caps bit.

  
  
  

• Vimm

  If I see it right you use Managed DirectX.

  It will not crash but you should expect an exception anytime you call a Managed DirectX method but it is even possible that the runtime will ignore it silently. As exception handling is “slow” in .Net you should avoid this.

  Anyway to make sure that your program runs on as many systems as possible you will have to check the caps and don’t use anything that is not available.

  To come back to your primary question. Why do you want to disable FSAA

  
  
  

• Kirk Quinbar

  Interesting...

  First of all, I have read that document (or a version o fit ) and thats how I got my point filtered gui to work. So that is really neat but is as I said earlier kinda pointless as fast as antialiasing is applied to it. The point of the gui rendering was that it should only render primitives textured by an equal big texture area and that it should point filtering so everything would be "blocky". When filtering / antialiasing is applied the smoothness appear and it just destroys the gui look.

  Well, to the other part. I have a GeForce 6800GT and this renderstate works perfectly for me. I've also tried on an ATI card which has this capability and it (of course) works there aswell. How come this works on my nvidia card that does not have this capability

  
  

• David Streeter

  \o/ Big thanks! It works just as you said. The multisampling no longer distorts the result. Issue more than resolved.
  
  

• Lovie

  I've not tried using it myself, and it's in native-DX .. but you might want to try looking at:

  D3DRS_MULTISAMPLEANTIALIAS bool value that determines how individual samples are computed when using a multisample render-target buffer. When set to TRUE, the multiple samples are computed so that full-scene antialiasing is performed by sampling at different sample positions for each multiple sample. When set to FALSE, the multiple samples are all written with the same sample value, sampled at the pixel center, which allows non-antialiased rendering to a multisample buffer. This render state has no effect when rendering to a single sample buffer. The default value is TRUE.

  ( for the SetRenderState() calls...)

  hth
  Jack

  
  
  

• HSA4733

  But you can not count on this because this renderstate have an Caps bit associated.

  D3DPRASTERCAPS_MULTISAMPLE_TOGGLE need to be set in the RasterCaps and there are many hardware out there without this feature.

  
  
  

• Len Z.

  Have you add this offset to the texture coordinate or the position I am asking because you write texel offset and not pixel offset.

  
  
  

• Mark Asztalos

  If I want to copy pixels 0, 1, 2, 3 and 4 from the texture to the screen I use texture coords (0 + 0.5 / texWidth) to (4 + 0.5 / texWidth) so I add 0.5 to the texture coordinates. I draw it to pixels 0, 1, 2, 3, 4, without any offset.
  
  I thought that was correct, but maybe I'm doing it wrong
  
  
• Disable FSAA for some primitives each frame? (disable it temporarily)