Question about 3D terms

[SasoDuck]

I haven't really focused on effects really before, so I'm not really sure what things are called. Like, I went to google how to make an explosion for real time with planes that are always faced towards the camera, but I had no idea what that's called. (at least I think that's how it works...)

I was just thinking of how to make the electricity on my sniper rifle (http://www.polycount.com/forum/showthread.php?t=76732) and was looking at how the explosion of a Halo plasma grenade (http://images1.wikia.nocookie.net/__cb20100406191403/halo/images/c/cf/Explosion_study.jpg) worked. The plasma dust and little electric parts looked like that's how they functioned.

[cryrid]

planes that are always faced towards the camera
Billboards.
http://forums.xna.com/forums/p/19034/99481.aspx
http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series4/Billboarding.php

Wiki also thinks it's now commonly just called sprite.

More often sprite now refers to a partially transparent two dimensional animation that is mapped onto a special plane in a 3D scene. Unlike a texture map, the sprite plane is always perpendicular to the axis emanating from the camera. The image can be scaled to simulate perspective, rotated two dimensionally, overlapped with other objects, and be occluded, but it can only be viewed from the same angle. This rendering method is also referred to as billboarding.
-http://en.wikipedia.org/wiki/Sprite_(computer_graphics)

[SasoDuck]

thanks

[SasoDuck]

oh, so it requires coding?

[cholden]

In a game, this would be handled via a particle system (billboarded sprite particles). Making particle effects can be a load of fun or extremely frustraighting when it's not working out. For art renders you can fake it by placing planes where it looks good in the image.

[cryrid]

so it requires coding?
Depends. Some engines might have instant support for it, others might require a quick script/bit of code. If you just want the effect in your 3d application's viewport, you can constrain it to the camera there.

[Eric Chadwick]

The plasma grenade electricity effect looks like a real-time procedural-animated texture on a billboard. But procedurals require some careful shader optimizing to make sure they're efficient enough to not slow down the scene too much.

More likely though it's a pre-created bitmap with an animated alpha-test threshold. Here's an example... thru the shader you just scroll a threshold value...
http://dl.dropbox.com/u/5913234/procedural_gradient_electricity.gif