[Cycles] Section - Camera Limits vs. Material

Does it make a sense to have a possibility set a “Camera Limit” for visibility by another object?
Does it make a sense proof Alt+B options?
Or section by material is sufficient?

Here are two examples of section techniques:

Blender can “section” objects by setting up camera “Limits”.

  • That sounds like great option if you need section some complicated object (like engine, house ect.).
  • Camera Limits does section throw whole object in a scene.
  • And you can see result immediately in 3D window.
  • But from this side of sectioning view it is totally usable if it can be done from camera view only.
  • Also fact that “limits” cut whole scene is not always appreciated.
  • And the biggest problem - light behave is not affected.


Note: In this time we have also “Clipping Border” Alt+B to see or hide part of object. It could solve minuses of “Camera Limits”, but “Clipping Border” doesn’t affect a render (also we can’t animate it) in this time.

Section by Material (Transparent+Backfacing):

  • You can section from any position.
  • And artifacts that were problem in 2.4x BI render looks OK in this Cycles render
  • You need to setup material to all parts manually


BTW: Can Cycles control texture coordinates by another object like BI already?

I love it. Could you share how you do the Section By Material with Cycles, because AFAIK, there’s no ramp texture for the moment.

Thanks for pointing me to this thread, the mapping of the Gradient texture is very clever. The downside is the settings of the mapping can’t be animated.

Not for now, you are right, but as whole blender also Cycles will fully animated one day.
But I hope in that time there is going to be option -control texture by another object :slight_smile:

Anyway in this time texture can’t be animated, but values in Mapping Node can be.
(I will post some anim test later.)

Between experimental builds is also Checker texture already so sharp edge works great here (I’m just a bit confused with mapping).

I want to try the Volume Shader Patch that can solve the faik limits.



An interesting thread. Bravo and a big thank you to all!

@michalis: thanks
It looks I will have to fix the title of this thread :slight_smile: zero comments to the topic -if the camera limits or clipping border (Alt+B) can be proofed to be something like Sketchups cross section tool.

Anyway, Cycles with Volume patch for textured section is going to be also interesting topic :slight_smile:

Here is the anim test:

first test of volume material
(blender build with Volume patch downloaded from graphicall.org)


Also adjust View clipping for this sort of thing - N key View Panel->Lens.

@chip4brains: thanks for note, but this option has all minuses of camera limits + 3Dview is not rendered

Here is some animation of volumetric crossection


Do you know how to get black&white sharp edge (for section factor)?
I used Texture>Mapping>Scale>X=1000.
I can’t find something like “Constatnt” option for gradient that internal has.

In your video there seems to be faded area on the ground plane that corresponds to the postion of cube when it shows the sectioning

Nice, I was looking for something like this. Need to check the volumetric patch.

For the sharp banding, use a “math” node with “greater than” 0.5. in between the “wave texture” and the “mix” shader

yes, it does! :slight_smile:

Sorry for late answer (a bit a busy life :slight_smile: )

@cnikiel: thanks man!!! that is what I was looking for :slight_smile:


@AlexDS: welcome to the club :slight_smile:

I’m impressed as sharp and heavy volume can be set via Cycles :slight_smile:
(The mesh is still cube :slight_smile: )



Yes to all three! but you need to add a subsurf modifier to view this but the “Apply Modifier To Editing Cage” isnt open to Python, AFAIK, so you can’t set a hotkey for it.
You can set up the other display options in the subsurf via hot keys though, so maybe that will be enough?
Nice work by the way!

I set up a material to be controlled by an empty. Makes it much easier to control how the limit is controlled.


limitstest.blend (516 KB)

Again you are doing wonders with the volume patch vklidu, I don’t know how many more times I need to have my jaw fixed before you stop amazing me :slight_smile:

Seconded that, very eye catching rendering. Sadly i still can not run it on AMD GPU, it will compensate a bit overall slowness.

@natew: OMG how did you get the empty work as controller of material position? I was waiting for that feature so long !!!
Even I open your blend in 2.64a (r51232) empty works, but where (or how) I can specify of what object coordinates will be used for section position? Thanks for help.

And sorry for ignoring your essential post :slight_smile:

For the material, it’s all controlled with the mapping node. What I did is set the attributes of the empty as drivers of the mapping node attributes. Sadly it all has to be done manually for now, but it works. As far as changing the object, if you look at the drivers for the mapping node, you can easily change the object, just be sure to do this for all of the attributes.

If you want, I can make a quick tutorial on setting this up.