Active Camera To Lightinfo.worldmatrix...?

[aspectdigital]

Gang,

I have a lightinfo node attached to a camera driving a change in material on an object as the camera approaches it. Unfortunately the lightInfo node only connects to one camera, but id like this effect to occur for all (5) cameras i have in my scene. SHort of saving a different version of the file with each camera connected separately in each file, id like to know if there's a way to use something (similar to a triple switch or something) to tell the renderer to find out which camera is actively being rendered, and connect that camera to the lightInfo node prior to rendering a frame.

Note: we've tried this but it doesnt work:

string $panel = getPanel -wf;
string $cCamera = modelPanel -q -camera $panel;
connectAttr -f ($cCamera + ".worldMatrix[0]") lightInfo1.worldMatrix;

Any and all help much appreciated

neX:)

[joojaa]

theres no panels when you render. NOTHING related to gui exist during that time. SO obviously you cant querry panels either.

But yes you can querry what the render globals is tied to. But i do suggest you put a switch node in place it makes this so much easier.

Also theres simpke trivial way too just run the renders form a batch and pass mel along with the render. Im supprised people dont use this more often.

[aspectdigital]

Jooja,

Hey thasnks for the feedback. Yes we were suspecting as you say the Panels are not active during CLI rendering.

I thought of the Switch node idea, but cannot connect it... either to a triple or quadruple switch, it just wont connect even if i try and force it. have you successfully done this? if so, would you possibly be able to elaborate on the procedure for me?

And with regards to "pass mel along with render..." i have NFI what you mean there? Could you explain a little further? Sorry im a bit of a n00b at this stuff, but im enjoying learning more and more... hopefully one day I can help someone else!! lol

Cheers

neX:)

[joojaa]

no shading switches (shading switches are for surface shapes ONLY) are something different altogether. IM was talking of a choice node (there are atleast 5 different choise type nodes in Maya that can reroute input output), again im a bit swapmed at the moment but ill have looksee at my luchbreak.

But now that i think of it your more interested in the sampler info node instead oif light info specifically point camera

[aspectdigital]

Jooja,

That sounds very interesting. However i cant for the life of me find the other type of switch/choice node you speak of. Could you please advise me where i might find one and what its' called?

Cheers

neX:)

[joojaa]

Ahh see its not listed in yoru hypershade... its still nonetheless there (you will have to amke it usiong mel, wich means it will not negotiate ito mr netwroks unless its the graph rank 0 item). BUt you dont actually need it use sampler info instead.

Could you tell me exactklly what your netwrk does and ill tell you how to convert this to using sampler info. (offcourse samplerinfo casn allso give the cvurrent cameras matrix if really really need be but its a bit awkward)

[aspectdigital]

OK,

so we discovered a kind of a solution for this issue (sorry jooja im a n00b at maya, and have nfi how to use the SamplerInfo node).

so what we've done (well, my colleague m@b has done), for anyone interested, is attach the WorldMatrix of a locator to the WorldMatrix of the lightinfo node.
We then point-constrained the locator to each camera, and set the weight to 0 for each constraint.
Then we can run a -preRender MEL command like "setAttr "treeLODdist_pointConstraint.cam_cameraW2" 1" to control which camera is affecting the texture.

Jooja, ill try and explain the puropose: We have avery large scene with a pretty terrible aerial image draped over some terrain. The aerial looks good from up high, but is horribly pixelated/blurry at close inspection. So we want to use the lightinfo node and a setrange to drive a ramp going inot the alpha of a layered texture which has the aerial at one extreme and a nice grass texture at the other. That way we can use the setrange to say, tell it to fade the aerial to a grassy texture from 400m to 800m away. I hope that make sense. Our problem is we have multiple cameras and want to link the lightinfo to the current camera without having to save off different files.

Im still pretty keen to hear how this sampler info node could be ised in a similar fashion.

Cheers

neX:)

[joojaa]

Then deifintely use sampler info. Sampler info has a output called point camera this gives out the camera space coordinates. Hook this output to a set range node (note camera space is aligned so that distances are in negative ranges) connect thet to a ramps u value connect the ramp as alpha.

Not only is this always smack on camera at all times no matter what camera your using its also faster to compute, becuse the data is computed anyway whereas the light info trick isn't. Sewcond it works in z-space distances not on curved space ones, and while curved space works okay it can have some nasty side effects on wide cameras mainly because the normal CG camera does not really work in curved space.

Sampler info is easier to hook up than the lightInfo is in the same category, so i cant really think of a reason why you couldn't use sampleInfo when you can use lightInfo (samplerInfo is the most important node for shader designers by the way). Its ain the same category as light info.