Nearest neighbor filtering under DirectX

Munger · Post by **Munger** » Fri May 04, 2007 4:19 am

I was just trying to turn off bilinear filtering using something like this:

node->setMaterialFlag(EMF_BILINEAR_FILTER, false);

It works under OpenGL, but neither the DirectX 8 or 9 renderers work - bilinear filtering remains on. Any ideas?

Munger · Post by **Munger** » Fri May 04, 2007 4:23 am

BTW, GeForce 7900GS under XP, current drivers

vitek · Post by **vitek** » Fri May 04, 2007 5:16 am

Probably because the code in the D3D8/9 drivers for filtering configuration is wrong. Notice how the following code doesn't even look at the filtering values other than anisotropic...

Code: Select all

if (material.BilinearFilter || material.TrilinearFilter || material.AnisotropicFilter)
{
  D3DTEXTUREFILTERTYPE tftMag = ((Caps.TextureFilterCaps & D3DPTFILTERCAPS_MAGFANISOTROPIC) && material.AnisotropicFilter) ? D3DTEXF_ANISOTROPIC : D3DTEXF_LINEAR;
  D3DTEXTUREFILTERTYPE tftMin = ((Caps.TextureFilterCaps & D3DPTFILTERCAPS_MINFANISOTROPIC) && material.AnisotropicFilter) ? D3DTEXF_ANISOTROPIC : D3DTEXF_LINEAR;
  D3DTEXTUREFILTERTYPE tftMip = material.TrilinearFilter ? D3DTEXF_LINEAR : D3DTEXF_POINT;

  for (u32 st=0; st<MaxTextureUnits; ++st)
  {
    pID3DDevice->SetTextureStageState(st, D3DTSS_MAGFILTER, tftMag);
    pID3DDevice->SetTextureStageState(st, D3DTSS_MINFILTER, tftMin);
    pID3DDevice->SetTextureStageState(st, D3DTSS_MIPFILTER, tftMip);
  }
}

I think it should be...

Code: Select all

if (material.BilinearFilter || material.TrilinearFilter || material.AnisotropicFilter)
{
   D3DTEXTUREFILTERTYPE tftMin = D3DTEXF_LINEAR;
   if (material.AnisotropicFilter && (Caps.TextureFilterCaps & D3DPTFILTERCAPS_MINFANISOTROPIC))
      tftMin = D3DTEXF_ANISOTROPIC;

   D3DTEXTUREFILTERTYPE tftMag = D3DTEXF_LINEAR;
   if (material.AnisotropicFilter && (Caps.TextureFilterCaps & D3DPTFILTERCAPS_MAGFANISOTROPIC))
      tftMag = D3DTEXF_ANISOTROPIC;

   D3DTEXTUREFILTERTYPE tftMip = D3DXF_POINT;
   if (material.TrilinearFilter && (Caps.TextureFilterCaps & D3DPTFILTERCAPS_MIPFLINEAR))
      tftMip = D3DTEXF_LINEAR;

  for (u32 st=0; st<MaxTextureUnits; ++st)
  {
    pID3DDevice->SetTextureStageState(st, D3DTSS_MAGFILTER, tftMag);
    pID3DDevice->SetTextureStageState(st, D3DTSS_MINFILTER, tftMin);
    pID3DDevice->SetTextureStageState(st, D3DTSS_MIPFILTER, tftMip);
  }
}

Travis

Spintz · Post by **Spintz** » Fri May 04, 2007 10:21 am

ummmm, shouldn't this -

Code: Select all

pID3DDevice->SetTextureStageState(st, D3DTSS_MAGFILTER, tftMag); 
pID3DDevice->SetTextureStageState(st, D3DTSS_MINFILTER, tftMin); 
pID3DDevice->SetTextureStageState(st, D3DTSS_MIPFILTER, tftMip);

be this -

Code: Select all

pID3DDevice->SetSamplerState(st, D3DSAMP_MAGFILTER, tftMag); 
pID3DDevice->SetSamplerState(st, D3DSAMP_MINFILTER, tftMin); 
pID3DDevice->SetSamplerState(st, D3DSAMP_MIPFILTER, tftMip);

I think D3DTSS stuff is old, maybe it should be that for DX8( I don't use it ), but DX9 is definitely D3DSAMP and SetSamplerState.

vitek · Post by **vitek** » Fri May 04, 2007 10:59 am

Yes, D3D8 uses SetTextureStageState() and D3D9 uses SetSamplerState().

hybrid · Post by **hybrid** » Fri May 04, 2007 11:39 am

I think the two fragments from vitek are the same besides the Caps check for the trilinear support. So there will be no more filter support than before!? So to say: It was correct and should have worked in all Irrlicht versions AFAIK.

vitek · Post by **vitek** » Fri May 04, 2007 5:17 pm

Haha, that's hilarious. I didn't even read the code I had in my copy of the video driver. I just blindly copy/pasted it. I remember there being an issue with these flags before 1.3, but never checked to see if it was fixed. Apparently now it is exactly the same as what I have, just formatted differently.

Munger · Post by **Munger** » Sat May 05, 2007 3:33 am

I never really thought about it, but looking at the code it seems filtering is set for all layers of a material. It would be nice to have per layer filtering. I'm sure it would be useful for something (although nothing springs to mind).

In my current project I'm using a character that's from the 8-bit generation so he should look like pixellated. It's no big deal for me to stick with OpenGL, but I'm not imagining things.

hybrid · Post by **hybrid** » Sat May 05, 2007 8:46 pm

Per-layer setting will come soon. If I can keep the API compatible with the old one (i.e. only extending the old one) it will be in the next version, otherwise it will be in the next API-breaking one.
But as said in the previous posts the filtering should work for both accelerated drivers!