Making A Value Change Based On Amount A Normal Is Facing "up"?

[sawasawa]

Hope this topic title isn't too confusing

I know with the samplerinfo utility you can specify a camera-dependent facing ratio to make values change based on how much the point is facing towards the camera.

Is there a method of making a value change based on how much of the point is facing "upward" or towards positive y value in world coordinates?

A real world example would be dust accumulation since the "top" of objects would accumulate more than its side or bottom

thanks!

[joojaa]

take the surfacenormal dot your vector.

[sawasawa]

thanks. would I be using the surfacesampler in cojunction with vectorproduct utility to do this or is there a different utility needed?

I tried hooking the "normal camera y" ouput of samplerinfo into "input 1 y" of vectorproduct1 node and then using a hard-coded value of 0,1,0 for input 2. dot product was the operation. I also hooked "matrix eye to world" of samplerinfo into matrix input of same vectorproduct1 node(was this wrong to do?)

I then took the "output y" of vectorproduct1 and hooked it into "value y" of "set range" utility with a min of 0 and max of 1 to clamp out negative colors

I took the final result from "set rage" and hooked it into the red component of my phong materials color input.

I get a y gradient color result on my test spheres by it is still camera-dependent! the gradient moves with camera

QUOTE(Joojaa @ 10/08/06, 10:12 PM) [snapback]249514[/snapback]
take the surfacenormal dot your vector.

[drblacksnake]

try snow texture

[joojaa]

camera y is allways upwards in your camera space so* if you tilt your camera your texture tilts also. Use world normal.

That is when you hit render everything in the scene is flattened as if theyd lie in the cordinate sytems of the camera (al

[sawasawa]

thanks for posts!

Snow shader does what I was looking for but not sure I can output it properly to what I need -will look into it more!

-Joojaa. is "world coordinate" a new option in Maya? I am using Maya 6.5 and don't have any world-based vector options or "world coordinate" options in my surface sampler ouputs that I can see(I only see world position).

[sawasawa]

got it to work. it needed to use vector matrix product operation under vector product utility. unfortunately it only works in Maya software renderer and not mentalray -perhaps mentalray doesn't recognize all of the feature of vectorproduct utility?

thanks again

[joojaa]

Use samplerinfo node!n The surface sampler dont work with mr very well.

[sawasawa]

"The surface sampler dont work with mr very well."

that sux!

thank again for help

[joojaa]

Everything thats not a shading node is omiitted form export. Maya sw reads all nodes but if you wnated them to work in MR youd need to wirete am mr node wiath same info but because the mr does not necceserily see teh same kiind of data ist not entirely trivial to do so.