Parallax Map Extrusion Technique

This video was produced several years ago in preparation for my Vision 2.0 engine, but I am only now getting around to posting it online.

I was attempting to provide for steeper viewing angles and depth-correct silhouettes without increasing the geometry count. This video contains just four triangles (two triangles for the blocker object, and two triangles for the receiver).

The shadows cast by the blocker object correctly flow over the imaginary isosurface formed by the heightmap texture of the receiving object because the shadow map pixel shader reads the height of the isosurface when determining whether or not the fragment is visible to the light source.

The edges of the shadow are softened by sampling the surrounding 16 texels of the isosurface (though not apparent in the video), and checking for light visibility against the shadow map.

The rest of the effect (which provides semi-correct surface estimation even at obtuse viewing angles) is accomplished using a screen-space technique with a minor precomputation step.

Vision 2.0 used this technique on almost all bumpy surfaces, regardless of complexity - but mostly restricted it to walls in the demo. The result is seemingly high resolution surfaces that can be viewed from any angle, including edge-on.

Thanks for viewing!

You can read more about my projects at http://www.bertolami.com.

A high-res version of this video can also be found on my website.

Category:

Science & Technology

Tags:

• 3D
• Engine
• Graphics
• Direct3D
• OpenGL
• Game
• Parallax
• Vision
• Bertolami
• Render
• Heightmap
• bump
• specular
• dot
• lighting

[platunit9]

Oh, yep! Technically the rear wall is 2 polygons, and the blocker (multicolored) object is an additional 2 polygons.

In response to the performance question, I've tested it out on a number of popular models (Buddha, Dragon, Bunny) as well as a few Doom 3 levels, and haven't noticed much of any performance drop. Apologies though - I haven't profiled it close enough to comment on specifics :(

[Jinseeker15]

this is unreal! Is this still parallax map, cause it looks like a direct x11 displacement map to me applied, it's displacing the silhouette as well a lot, not a feature attainable with normal map/parallax maps if i am not mistaken.

[superkellerman8D]

so how many polygons is this? Two? you don't say! :D

[AttaKru]

yeah, impressive, have you done some performance measurement with the shaders ? how does it behave on hundreds of polys ?

[agustinbs]

impreasive!

[UCSDvislab]

No one has commented on this? Too bad...I think you've done a great job preserving the paralax!