Node Challenge

#1
Node Challenge #1

Hi all,

I've been thinking that it would be instructive for all to have a node challenge, where we try to push the limits of the node system and find solutions to specific problems. This way, we can all learn from each other and expand the potential of the node system.

I'm going to give 10 days for the submission of entries (until January 31st). It would be nice if the entries were accompanied by a render and a simple explanation of what you did.

The goal of this first challenge is to recreate in Cheetah3D something similar to what is explained in this blender tutorial.

I'm attaching an image to better explain myself.

Good luck to all and I look forward to seeing your solutions!
 

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archie

New member
#2
:confused:

i know in vue the boolean actually applies correctly the mats of the participants, but in cheetah i don't know a way to distinguish faces.

:frown:
 
#3
I can see that one. Just do a dotproduct on the normal vector and an axis <1,0,0>, <0,1,0> or <0,0,1> . If its really close to 1.0 then make it red otherwise blue gray.
 

archie

New member
#4
I can see that one. Just do a dotproduct on the normal vector and an axis <1,0,0>, <0,1,0> or <0,0,1> . If its really close to 1.0 then make it red otherwise blue gray.
but how do you avoid that parallel faces in the mesh don't get included ?
i tried that once and had, translated to this one, red spots on the opposite side.
 

archie

New member
#6
but how do you avoid that parallel faces in the mesh don't get included ?
i tried that once and had, translated to this one, red spots on the opposite side.
ok bugaoo wins, it works.

you start with the directional node and make the plane you want to color white, the others black.
the step node with edge=1 gives only 1 when the input is 1 (??!!!).
it mixes the mesh vs intersect color.

andreu, next one !

View attachment intersect.c3dmat.zip

Bildschirmfoto 2010-01-21 um 22.46.12.png
 
#7
you start with the directional node and make the plane you want to color white, the others black.
what if the section plane isn't aligned to x,y,z but randomly oriented?

but, first, i'm not understanding if we have to cut the object with an arbitrary and movable plane (the way SketchUp does) or with a boolean operation. or simply take an already cut object? Andreu?

BTW congrats Bugaboo and Archie, it's always hard to be the first...

cheers,
A
 

archie

New member
#8
what if the section plane isn't aligned to x,y,z but randomly oriented?

but, first, i'm not understanding if we have to cut the object with an arbitrary and movable plane (the way SketchUp does) or with a boolean operation. or simply take an already cut object? Andreu?
hi alessandro !

i never stepped into blender, so i have no idea what the guy in the tutorial was doing, what i got from it though was that in the blender node system intersections can be detected (and then colored), unlike in cheetah which lacks such input.
what you can do instead, as bugaboo pointed out, is to detect all faces with certain direction = normal values and then color them. it should be doable with tilted planes as well, only then you have to go bugaboo's way with dotprod node.
i maintain though that this method will color all faces of that directionality, including such not part of the intersection, which is highly unlikely in case of a subdivided mesh (but a cube would show).

update: come to think of it, it should be possible to use the position of the state node to exclude parallel faces not in the intersection plane...
 
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#9
Archie and bugaboo:

Sounds like you guys found this an easy challenge :) Good work there! :icon_thumbup: Archie, Would you mind posting a simple file where you demonstrate your method? Posting the material would usually be enough but I'm having a bit of trouble reproducing your results :redface: You guys know too much for me :)

@ Alessandro: either boolean or plane intersect would be nice, not sure it is doable in C3D. I think that even a simple normal direction solution would be good, although not as useful.

I already have an idea for the next challenge, I'll post it soon. I hope it gives you a headache :D

Andreu
 
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#10
Archie, Would you mind posting a simple file where you demonstrate your method? Posting the material would usually be enough but I'm having a bit of trouble reproducing your results
View attachment intersect.jas.zip

hi andreu,

the mat does color yz-plane-intersections (perpendicular to the x-axis: white color of the x-input of the directional node).

you can do y or z instead, for tilted planes i need to write sth different :wink:


update:

- just to further confuse you :tongue:

Screen shot 2010-01-22 at 8.31.50 PM.png
 
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#11
Node challenge #2

Archie, that is outstanding!!! You da man :) Thanks for providing the file, that explains a lot. You are using booleans, that makes sense. Good job!

OK, here goes node challenge number 2.
I saw this image post-processed with nodes in blender. By the way, sorry to keep referring back to blender. It's not my intention to have that program as my benchmark or anything. It's just coincidence. I just wonder if something like a glare effect would be doable with the current node system. You guys I'm sure can figure it out.

Anyway, there is this tutorial about neon lights for blender. The link is here. In the end the author uses compositing nodes to create a glare. There is a glare node in blender. I'm pretty sure this would be impossible in the current state of our node system, but maybe there is a way to fake it. Anyway, it's all in the spirit of trying new things and learning. I'm sure I'd like to have compositing nodes in C3D, but we'll work with what we have.

To clarify, you can fake it and cheat as much as you want, as long as we get a glare. Not a neon glow (that even I can do), but a glare coming off a light source or the like.

I'm attaching the image to be more specific.

Toldya it was hard :D

Andreu
 

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#12
lol andreu, that was hard :smile:

when you place an emissive object close to a wall, it will look as if there was a glow because of the diffuse reflections.
so something like in the blender pic could easily be reproduced with emissive and radiosity alone.

but of course i could add my mist from the piggy thread for some blurring.

now i realize that i cannot save the file on my imac, will try to reproduce on the macbook and post...

image.png

image2.png

View attachment glow.jas.zip

update

ok this needs more finetuning (definitely easier in front of some aged concrete) but you can see the direction:
a soft inflated shape around the emissive object and then using the i-n node, softened, into emissive and transparency blur, don't forget the render tag.

c u tomorrow !
 
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#13
Well, Iwas not referring to the glow, but a glare. A glare is an artifact created by the light hitting the lens of a camera and creating extraneous light bouncing effects, which are not in the "world." I will try to find other examples if it is not clear what I'm asking for.

Andreu
 
#17
Well, this is no attempt to win a contest or anything, but you could put a plane in front of the camera and apply a blurring transparency mat on the plane. Would that work? I did that once and simply moved the plane across the camera view to look like wind...worked well.
 
#18
Well, this is no attempt to win a contest or anything, but you could put a plane in front of the camera and apply a blurring transparency mat on the plane. Would that work? I did that once and simply moved the plane across the camera view to look like wind...worked well.
Yeah, show us a render, please. Sounds like a good idea. :icon_thumbup:
 
#19
Well, this is no attempt to win a contest or anything, but you could put a plane in front of the camera and apply a blurring transparency mat on the plane. Would that work? I did that once and simply moved the plane across the camera view to look like wind...worked well.
robert, absolutely.

this is a funny challenge:

firstly, this guy from the blender tut applied this totally unnatural motion blur effect on his render, maybe because it was available, who knows.

of course the easiest way would have been to do a second moblu layer in photoshop !

now andreu, for the sake of learning what's possible with the new cheetah nodes, posted this contest.

now everyone is challenged to avoid the obvious, an alpha mat plane ...

:smile:
 
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