Get the pixel size in shader for homemade MipMap

Valmond · Post by **Valmond** » Fri Mar 06, 2009 2:22 pm

Hi

I have done an Atlasmap for my terrain created by FreeWorld3D and it works okay except that I can't create it with MipMap generation set to true (bleeding around the edges).
So I thought I'd generate the MipMaps myself which brings me to the problem on how to select the right LOD in the fragment shader??

I'v searched tons of "texel size" etc. on google and in the forum but I just can't lay my hands on that pice of code that'll give me the size of the pixel the fragment shader is suppoised to draw (well, the pixelsize in texelspace i guess).

I didn't know if I should post this in the Off-topic or not, sorry if I should have.

bitplane · Post by **bitplane** » Fri Mar 06, 2009 4:20 pm

I'm no shader whizz but I did solve a similar problem a while back, the answer was the "fwidth" function.

Nadro · Post by **Nadro** » Fri Mar 06, 2009 10:54 pm

You can also look on this (Sub-tiling):
http://www.gamedev.net/community/forums ... cyear=2008

Valmond · Post by **Valmond** » Sat Mar 07, 2009 9:49 pm

bitplane got me running for over a day and Nadro confirmed what I'v found

Thanks !

Guess you can't get the pixelsizes with 'old" shaders like the 1.2 (Nadros link says you'll need like at least 3.0 shaders)?