Hand editing anisotropic maps to fake perspective?

Petethegoat · Dec 2016

A couple of years ago I either thought of or read about faking perspective on textures using aniso filtering.

Since we can infer the perspective from the particular mip level that's being picked, we can modify our texture to take advantage of that- basically going from the grass texture on the left, to something like the texture on the right; (both found on google)

Image: http://www.telekineticfrog.com/junks/grassTile01.jpg

Image: http://semiseriousgames.com/blog/wp-content/uploads/2013/05/grass_x1.png

In short I'm wondering if anyone has tried this, if it's been used anywhere, and also any opinions on if it could actually be useful. I'm assuming the answer to all those questions is no.

Eric Chadwick · Dec 2016

I don't see how this would produce a good looking result?

The first texture is meant for a semi-horizontal ground surface, but the second is meant for a vertical billboard (with alpha). How would you expect to transition between these?

We have an example here of adding color to lower mips to fake fog or fresnel.
http://wiki.polycount.com/wiki/MIP#Mip_Fading
But typically this is not worth the authoring effort, and runs into other problems like other nearby meshes not matching the same look.

ZacD · Dec 2016

Rocket League kinda stacks those 2 textures in a # like grid.

Eric Chadwick · Dec 2016

You mean an atlas?

Petethegoat · Dec 2016

Eric Chadwick said:

The first texture is meant for a semi-horizontal ground surface, but the second is meant for a vertical billboard (with alpha). How would you expect to transition between these?

Sorry, I'm not expressing myself very clearly. Ignore the alpha on the billboard- here's a quick mockup of some (very) abstract blades of grass.

The middle image is equivalent to our traditional grass texture, and on the right is what the first aniso mip might look like.

Eric Chadwick · Dec 2016

That would only work if you had a game with a locked isometric camera angle.

If you used a perspective camera and you tiled that on the terrain, the texture would not create any parallax between bottom of grass stem and tip, so it would look bad anywhere but exactly in the middle of a straight-aligned camera.

If you panned the camera left or right, I think it would also break.

Best thing is to try it and see. Nothing beats actually experiencing it, opposed to just theorizing.

JedTheKrampus · Dec 2016

https://www.artstation.com/artwork/lDQEV

Take a look at the article about 2.5d texturing in Vertex 3.

Obscura · Dec 2016

Yep, 2.5D could be the way depending on your camera setup. The another thing that could work and would be fairly cheap is the "ryse moss technique" Or even parallax with a few steps\iterations. Or a more simplified implementation of that - See "Bump offset - Unreal Engine"

gnoop · Dec 2016

Nothing is wrong actually with making it the way you suggested. It's one of the basic tricks with texturing that is in use since very beginning. Yes. it would look good only within a certain camera angles. Certain range of view angles to be more specific. But at least within that range it would be looking right , while with opposite direction of view it would be same bad as flat stamped in your first example. The trick only is to choose right angle , right dominant direction on the scene, right place where such view dependent projection is logical etc. Not necessary with isometric games only. Just do it not too stretched. It's a matter of taste and feeling the limits.

Hand editing anisotropic maps to fake perspective?

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