NV_texgen_reflection software equivalent

OpenGL OpenGL: Advanced Coding
1

Since GL_NV_texgen_reflection is not supported on older cards I have to fallback to software texcoord generation if this ext is not supported.
I have searched all the web but found nothing except Brian Pauls Mesa3D library. But you know this library is so Messy, that I cant figure out whats going on.
I anyone could drop me a link with valuable information about generating normal and reflection map I would be very thankful.

mk

2

Just do;

For every vertex, calculate vertex to eye vector, and reflect that in the normal, and use that as the cubemap tex coords.

3

Isn’t it just a normal reflection calculation?

R = 2(N•L)N - L , where you replace the Lightvector(L) to the EyeVector instead?

But what use can you have of it on older HW:s? it makes a lookup in a cubemap if i understand it correctly, and older hardware that doenst support NV_reflectiom ( or similar) doesnt support cubemaps either…

4

Thanks Mazy. (N?L) means (N dot L)?

But what use can you have of it on older HW:s? it makes a lookup in a cubemap if i understand it correctly, and older hardware that doenst support
NV_reflectiom ( or similar) doesnt support cubemaps either…

NORMAL_MAP can be used also with 2D textures. I use NORMAL_MAP for simple light reflections on objects. My app will probably be run on a laptop, with very poor card, that doesnt support this extension.
Thanks

5

? looks like a dot in my browser

isnt the 2d equalent of reflection just a simple sphere_mapping?

6

Originally posted by Mazy:
[b]? looks like a dot in my browser

isnt the 2d equalent of reflection just a simple sphere_mapping? [/b]

Really? I have to check it tonihgt. I thought that sphere mapping doesnt use normals. And now it shows up that it does!