Fast Lighting?

[Siwko]

I've been looking, but haven't found. Can anyone enlighten me or at least point me in the direction of resources on speeding up lighting for OpenGL.

I currently take a huge hit in framerate when I enable lighting for my app.

Somewhere to the effect of 50%-80% frame rate loss.

If I can get down to 10%-20%, I'd be happy.

Please note: Poly Counts of 70,000 - 500,000 are easily realizable, so I'm shooting for a solid 15 fps if possible.

Thanks

Siwko

[Humus]

I guess you would opt for a hw T&L for that.

[Siwko]

Originally posted by Humus:
I guess you would opt for a hw T&L for that.

I can't. I'm limited to PCI video cards, and they have to be consumer level to boot. Sorry, no CAD cards allowed.

[Humus]

I guess you have to reduce the polycount ...

[Siwko]

I already have reduced polys. Generally a 70% reduction. I can't go any lower or I'd be losing too much resolution.

[MikeC]

How about precalculating vertex colours for your static geometry, instead of lighting on the fly?

[Glenn Upton]

IF you are displaying your lights with quadrics with material properties of GL_EMISSION that for sure takes a performance hit.

[Siwko]

I'm using base primitives. Mostly triangle fans and strips. I'm not using any quadrics or anything fancy. In fact, I'm not even scaling, so I believe I've turned off GL_NORMALIZE.

The other thing is that I'm getting a strange effect with the light. On a cylindrical model, if I rotate the part about the y-axis (just turn the faces), the lighting spot moves to the point where it is out of sight. It implies to be that the light is moving, but it shouldn't be. Ideas?

(Its not really as important as fast lighting though)

[paolom]

Apparently, the light position is in the object space of the cylinder, so it's being transformed by the modelview.
Also, remember to update the spot direction (it is transformed by the inverse of the modelview matrix current at the time of calling glLightf).

[This message has been edited by paolom (edited 05-25-2000).]

[Serge K]

to Glenn Upton:

> IF you are displaying your lights with quadrics with material properties of GL_EMISSION that for sure takes a performance hit.

Can you explain it, please?
I always thought, that the GL_EMISSION is a simplest & fastest part of lighting calculations.