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I would like to render a cut through an object using Freestyle. Is there a neat way to cut away a part of the mesh in the rendering (not for real) without using

  1. The cut tool (manipulating the mesh)
  2. Cutting the mesh with the camera (placing an orthographic camera inside the mesh) but limiting view options
  3. I got the boolean modifier to work with a remesh modifier as well, making things more complicated.

I was looking for something similar to the AltB option in the viewport. Or setting up a material on another object to render the intersection part invisible but leave the rest of the mesh visible.

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  • $\begingroup$ Why not use a boolean modifier enabled only for rendering? $\endgroup$ – gandalf3 Sep 1 '13 at 6:48
  • $\begingroup$ oha thanks thats a nice idea. At octree 9 at least the viewport will be smooth $\endgroup$ – miceterminator Sep 1 '13 at 6:50
  • $\begingroup$ What do you need the remesh for? If you only use the boolean for rendering, you don't have to worry about topology. $\endgroup$ – gandalf3 Sep 1 '13 at 6:53
  • $\begingroup$ the Mesh is not closed therefore the boolean modifier does not work without the remesh $\endgroup$ – miceterminator Sep 1 '13 at 6:55
  • $\begingroup$ I have updated my answer with another solution. I'm not sure how freestyle could help much with this problem, but I am still only learning the basics.. Another option is to make the mesh manifold manually or by applying the Remesh modifier. (or simply disable it in the viewport) $\endgroup$ – gandalf3 Sep 4 '13 at 1:07
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One way of doing this without modifying the actual mesh at all is to use a texture to define the transparency of the mesh:

Cycles:

example node setup

To create something similar to the AltB option, you could:

  1. UV unwrap using U> project from view:

    enter image description here

  2. Use the UV coordinates to define the transparency of the mesh by using this nodegroup:

    enter image description here

    enter image description here

Blender Internal:

  1. Enable Z transparency in Material settings → Transparency, and set alpha to 0:
    Z transparency
  2. To make the texture to affect the transparency of the material, enable Alpha in Texture settings → influence:
    Texture settings

Another way to do this is by modifying the mesh only when rendered.

e.g with a boolean modifier:
boolean and remesh

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    $\begingroup$ Why the down vote? Is there something wrong / inaccurate with my answer? Please say why so I can improve it. $\endgroup$ – gandalf3 Sep 4 '13 at 19:14
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I did the following:

  • Place a camera at 90° to the plane to which you want to have the cut
  • Select the camera
  • Under the camera settings, adjust the clipping start value

See how the result changes in the preview (and also in the render) when increasing the clipping start.

Clipping value 0.1 (as usual):

Clipping 0.1

Clipping value 10.2:

Clipping 10.2

Output in case of freestyle rendering:

Freestyle rendered clipping

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