Why use sprites at all

WooHoo 2 posts in one day.

I have read several discussions on sprites and single surface stuff but dont seem to be any the wiser. If I have read correctly, when you create a sprite, its actually a quad (2polys) that you are creating, if thats the case, then why not just create a quad and forget about sprites.

The reason I am mentioning this is because I want to create a halo/corrona around lights I have created, and i have been informed that I should do this with sprites. If I use a textured quad and copy the entity ( I presume this would be equivalent to single surface) would this not be faster.

After reading back over what I have wrote, I realise that I dont really know what Im talking about.

Please help.

One reason you might want to make a sprite instead of a Quad is because making a quad is more difficult. Blitz isn't a language only for pros who know how to transform points and construct meshes from scratch. :-)

Another reason is for z sorting. If you have objects with alpha in your scene, like trees, then if all your quads are in one mesh, then they will all use the same point (the center of the mesh) to dtermine what z order to draw in. So they'll all draw in front of certain trees and all draw behind certain other trees.

But if you have srpties then they're all seperate objects and will each use their own center to dtermine draw order.

Plus it's easier to fade them out as needed as a sprite, though if you're clever you can fade them out with vertex colors so that's not a major reason to use them.

Plus, with sprites, it's much easier to get them to constantly face the camera, of course.