I'm wanting to indicate various things using a "pie slice" sort of shape as below. Similar to vision cones in stealth game minimaps, or targetting indicators in RTS type games for frontal area attacks. Something generic enough to be used for both would be ideal.

I need to be able to procedurally (and efficiently) change things like the slice width and length, color, transparency, position in the world, etc. For my particular situation, there's no concern with elevation, funky terrain, or really any third axis at all as far as this element is concerned.

I have two first inclinations on how to accomplish this: 1) Manually generate the vertices for a main triangle, (possibly two, superimposed to get the border effect), a handful more to approximate the arc at the end, and roll it into a mesh.

2) Use some sort of 2D drawing library to create a circle and mask it off at the right angles, render to texture, and use that.

For reference, I have some experience with Ogre3D, but I'm not attached to it as this is a mostly academic pursuit at the moment. Other technologies that might be better at accomplishing this are more than welcome.

Finally, I'm kind of curious about how to do a "flashlight" or similar 3D effect that could produce the same result, but on all surfaces in the lit area.