[RichG]

Hi - I'm in the very early stages of testing for a job where I need to create some neon and I've hit an unexpected snag with Maxwell. I've created a very simple tube shape and applied my emitter material but it only emits on the tips of the tubes. To test I replaced the materials with basic luminous Cinema materials and did a standard Cinema 4D render so you can see the problem:

http://www.loopcorp.com//Miscellany/Neon_Test_0006.jpg

So it isn't down to the mapping, is it something to do with there not being enough energy in the light to show on the whole surface? I tried ramping up the exposure and there isn't a point where it starts to appear. I simplified the model down to a 6-sided tubular shape but that didn't help. I also exported the model out as obj to Modo where it rendered fine and reimported that to Cinema (ie: to kill the procedural nature of the sweep nurbs object) but still no luck. The test object is only about 50cm wide so it's not a matter of being modelled too large. Any ideas?

Cinema 4D R13.029
Maxwell_for_Cinema_4D-2.5.1.8

[JDHill]

It is caused by applying the same emitter to geometries of differing area; if you check in Studio, you'll see that a Sweep NURBS produces its sweep and cap geometries as separate pieces. For an emitter of N watts, then, the caps will shine more brightly than the sweep, according to the ratio of their respective areas. To get around this, you would not need to export/import: you could run Current State To Object on the Sweep NURBS, then Connect on the resulting hierarchy. Alternatively, depending on your requirements, you could simply disable the caps on the Sweep NURBS, so that you only have the sweep geometry.

[RichG]

I did try that. And I connected all the parts and optimised geometry to make sure. Then, as I said in the first post, I even exported as obj and re-imported so I was sure it was very basic geometry but it still didn't work.

However, I just did a test switching off the end cap altogether and that does work, but it's not going to be possible to model that way for the actual job.

[JDHill]

I did try that. And I connected all the parts and optimised geometry to make sure. Then, as I said in the first post, I even exported as obj and re-imported so I was sure it was very basic geometry but it still didn't work.

"didn't work" is a bit ambiguous: does it mean that after joining everything together, the end caps were still over-bright? If so, I don't see how that's possible, and would recommend taking a look at the scene in Studio. If not, in what way did it not work?

[zdeno]

flip normals ?

[RichG]

"didn't work" is a bit ambiguous: does it mean that after joining everything together, the end caps were still over-bright? If so, I don't see how that's possible, and would recommend taking a look at the scene in Studio. If not, in what way did it not work?

That first render is the result of the troubleshooting I'd already done so that's raw geometry, not a sweep nurbs object. So yes, after joining everything together, the end caps were still over-bright. However, see next message...

[RichG]

flip normals ?

Bingo! Thanks Zdeno. I knew it would be something I should have already checked. I've never noticed a converted sweep nurbs having inverted normals before but here it is, correct on the caps but inverted down the length:

http://www.loopcorp.com//Miscellany/Normals.jpg

[zdeno]