noob question - What is a Cube Map?
polycounter lvl 11
I'm touching up a couple of folio pieces and one of them is involving some glass. The glass I've got looks like poo and I'd like to add some reflections/ambiance to it.
I've searched the wiki and I've got a little bit of information but I'm still quite unclear as to what exactly a cube map is, how to create one and what I'm supposed to do with it once it's created.
UE3 has some seriously complex materials attached to reflections in general, but I'm more used to just identifying some sort of picture, making the material reflect, press render and be done with it. And is there a simpler way of just adding some subtle shine/reflection/distortion to a material to make it pop in UE3?
In this 'current-gen' world I obviously have to do some more learning. Lots of searches haven't yielded me much information on WHAT it is and HOW it works. Appologies if this information is lost in a thread somewhere.
I've searched the wiki and I've got a little bit of information but I'm still quite unclear as to what exactly a cube map is, how to create one and what I'm supposed to do with it once it's created.
UE3 has some seriously complex materials attached to reflections in general, but I'm more used to just identifying some sort of picture, making the material reflect, press render and be done with it. And is there a simpler way of just adding some subtle shine/reflection/distortion to a material to make it pop in UE3?
In this 'current-gen' world I obviously have to do some more learning. Lots of searches haven't yielded me much information on WHAT it is and HOW it works. Appologies if this information is lost in a thread somewhere.
Replies
http://utmapping.wikidot.com/how-to-build-a-simple-cube-map
Source has something similar but actually more automated and all you end up doing is placing cubemap entities around the map, run it and enter a command which builds all cube maps.
also check out... http://www.debevec.org/Probes/
and its parent site, it has a wealth of knowledge of reflection maps, including a brief history.
As far as I know, cube maps are 6 images stitched and warped together to form a seamless spherical image. Like a panorama but includes up and down.
There are also half a dozen ways to build cube maps manually, including rendering them out of 3dsmax or Maya (can't find any tuts on doing this but it can be done!).
Or you can stitch them together in PhotoShop and use the Nvidia DDS plug-in to save it out. There are also some really crazy methods involving chrome spheres and camera angles...
create cubemap from a photo?
cube maps can come in different variations, a strip 1x6 (dds), a cross, or six seperate images which you link one in and the given the correct names the others are linked in automatically
Here's a nice blog post about the subject that explains the concept.
http://blogs.msdn.com/shawnhar/archive/2008/03/04/cubemaps-the-salt-of-computer-graphics.aspx
More interesting is how you sample a cubemap. Cubemaps are just a specific format for storing bitmap textures. You usually samples 2d textures with UV coordinates, while you sample a cubemap with a vector.
The output value will be the color of the texel that vector would hit if its origin is the center of the cube (http://www.paulsprojects.net/tutorials/simplebump/cubemap.jpg). Changing the vector you input and the kind of cubemap you are using can give you various results. The most common way of using this is to input a reflection vector, but it could be anything, like the normal if you want to do ambient lighting for example
Create cubemap from photo?
Plus this might help.
Reflections in UE3 (Cubes? Cameras? Tutorials?)
Vampyre_Dark, that's a great link, thanks. I remember him doing some interesting tech at Climax back in the day.