Artifacts with DE rendering

[3dickulus]

http://www.fractalforums.com/fragmentarium/problem-with-maps/msg89110/#msg89110

Code:

/// in a frag this should create a mipmapped texture with 1000 levels
uniform sampler2D myTexture; file[test.png]
#TexParameter myTexture GL_TEXTURE_MAX_LEVEL 1000
#TexParameter myTexture GL_TEXTURE_WRAP_S GL_REPEAT
#TexParameter myTexture GL_TEXTURE_WRAP_T GL_REPEAT
#TexParameter myTexture GL_TEXTURE_MAG_FILTER GL_LINEAR
#TexParameter myTexture GL_TEXTURE_MIN_FILTER GL_LINEAR_MIPMAP_LINEAR

...but I don't think this will cure the aliasing 
you are using v1.0.0
this wasn't added until v1.0.10 so after this version you should see all of the available texture parameters in the menu...

Edit->
         Insert Command->
                                      Host Preprocessor Commands

the default is no mipmaps if user has not set it in the frag as above

[Crist-JRoger]

So i downloaded last fragmentarium and played with TexParameters. They do worse. All height-mapped area has artifacts... GL_LINEAR_MIPMAP_LINEAR, GL_LINEAR_MIPMAP_NEAREST...GL_NEAREST_MIPMAP_NEAREST... - nothind helps. Any ideas?

[Crist-JRoger]

Added a lot of dither noise  but still aliasing 

Code:

float dt = FDither*(rand(q.xy*(float(subframe)))/1000);
hcolor = texture2D(tex, htextoff+(q.xy)*htexturespeed)*hintensity-dt;

And another thing - in this image i used white pic with red squares. But heightmapped image has red-black-white transition (not from AO). I think that black is from dither noise. How to correctly use dithering?

[3dickulus]

...but I don't think this will cure the aliasing 

...the default is no mipmaps if user has not set it in the frag as above

for the heightmap texture I think "no mipmaps" is correct because the texture represents an object of fixed geometry, unless you are accessing the mipmap layers directly for something

the aliasing artifact I see is on the columns under the "height" pixels, someone correct me if I'm wrong on this please, this part of the image/object is generated by the heightmap frag code and would not have anything to do with how the texture is wrapped, clamped or mipmapped, but has everything to do with how the facet is calculated between height pixels. In the case of using a mipmapped texture, when reading pixels to use as a heightmap you would still see these artifacts between pixels of varying height, you just wouldn't see single pixel columns unless the texture is accesed @ 1/1 scale

the mipmap settings do exactly what they are supposed to do regarding texture rendering, left = no mipmaps, right = mipmaps

[Crist-JRoger]

All that I understood - these texparameters have no relation to the subject.

[Patryk Kizny]

Crist, I think we pointed out the problem earlier. Height-maps rendered within DE function will not be clean because "de = p.z + something" is not a true DE, but a rough approximation. The more height you add, the more artifacts you'll see. You'd need to go for bruteforce or other raymatching instead of DE.

[Crist-JRoger]

I was hoping to solve the problem exactly to DE...

[3dickulus]

The pixellated pattern you see is a result of mipmaps issue.

perhaps this issue would best be served by introducing a geometry shader instead of piling more (unnecessary) work on the fragment shader

heightmaps usage <a href="https://www.youtube.com/v/v2b4yQ61lKI&rel=1&fs=1&hd=1" target="_blank">https://www.youtube.com/v/v2b4yQ61lKI&rel=1&fs=1&hd=1</a>

[Crist-JRoger]

heightmaps usage

I would like to users will see something like this in Fragmentarium 

[Patryk Kizny]

Sounds like a way to go. I don't see a point doing 'normal' terrain in fragmentarium.

[Crist-JRoger]

We need GLSL-guru