Cg projective & non projective texture query

I have tried searching on google but to no vail, could any1 please tel me the difference between projective and non projective texture query.

Also, how does texRect work? using that I presume I can bind textures with width and height of not power 2.

Thanks for your help.

It is all in the reference…

Nonprojective texture lookup queries a texture using (s, t, r) coordinates as they are passed to a fragment program.

Projective lookup uses (s/q, t/q, r/q) lookup(projective transform). This allows you to do some special tricks, like projection a texure

texRect is sampler for GL_TEXTURE_RECT_NV

thanx a bunch…

I ws wondering another thing. I have to project a point into an image, whoses camera projection matrix I have. This point is then queried in texture.

On just multiplying, the projection matrix with point coordinates, I get negative coordinates for x and y, which is confusing me.Are these correct? if yes, then wuld just query with thses in texture give me the correct result that I want.

if not, then do i use gluProject() to get the coordinate to query. or is there any other way.

I have set the viewport to my texture size for gluProject function.

Thanks for help.