<p>I am trying to model an organic object using OpenSCAD. However this will need to be ported over to older software. This restricts the primitives I can use (only cone, cylinder, torus, sphere and cubes) and the operations I can perform (difference, union, intersection, scaling and transformation). However modeling with these restrictions gives very unnatural looking objects. I need to somehow implement by hand, using only these primitives/operations the hull and minkowski operations to give my models a more organic look. Does anybody know how this could be done?</p>

CC BY-SA 3.0
2016-03-15T17:35:16.007Z
Given this and your previous answers is there a reason why you do not use nurbs and B-Rep?
joojaa
CC BY-SA 3.0
2016-03-16T08:14:08.810Z
Yes. Whatever I build must then be uploaded in CSG format to a very old piece of software that then does raytracing on it. And the old software is setting up some STRONG restrictions on functions. However I seem to have found a workaround. As soon as I get approval on the figures I'll post my current solution.
RCountZero
CC BY-SA 3.0
2016-03-16T08:28:55.827Z
Yes but if you could tell what the old ray tracer is then we can come up with better solutions. I mean first you tell use it has to be torus and sphere cylinder etc. than you relax it to hull and Malinowski functions. Neither one of those alone are perfect solutions. But given artificial restrictions that are there because you think you are restricted in this way is not effective communication.   B-Rep is for most part CSG.
joojaa
CC BY-SA 3.0
2016-03-16T09:19:58.120Z
You are indeed correct. The final object must be constructed in Craig E. Kolb's Rayshade program and it must be inputted as a text file. I am still not allowed to use commands such as Hull or Minkowski since they are not available in Rayshade. I was looking for a way to simulate them. Up to now I've had (in my opinion) relative success by taking three projections of the objects and then intersecting them.   Documentation about Rayshade can be found in here: http://graphics.stanford.edu/~cek/rayshade/doc/guide/guide.html
RCountZero
CC BY-SA 3.0
2016-03-16T10:32:09.303Z
Howabout using sweptsph that gives you quite some options.
joojaa
CC BY-SA 3.0
2016-03-16T12:58:44.057Z
It turns out that intersecting the projections from three different views gives me an acceptable quality. I will check swepthsph if I need extra smoothness in the figures but for now the method I'm using is enough. Thank you very much for taking the time to help.
RCountZero
CC BY-SA 3.0
2016-03-18T10:07:37.767Z
The reason nobody suggest the 3 projection boolean is because it does in fact not work for nearly any sensible case.
joojaa
<transformations><3d><model>
OpenSCAD Hull/Minkowski function by hand?
RCountZero
# OpenSCAD Hull/Minkowski function by hand?

(Asked by: username_0 on 2016-03-15)

I am trying to model an organic object using OpenSCAD. However this will need to be ported over to older software. This restricts the primitives I can use (only cone, cylinder, torus, sphere and cubes) and the operations I can perform (difference, union, intersection, scaling and transformation). However modeling with these restrictions gives very unnatural looking objects. I need to somehow implement by hand, using only these primitives/operations the hull and minkowski operations to give my models a more organic look. Does anybody know how this could be done?

**Tags:** transformations, 3d, model

> **Comments:**
> **username_1**: Given this and your previous answers is there a reason why you do not use nurbs and B-Rep?  
> **username_0**: Yes. Whatever I build must then be uploaded in CSG format to a very old piece of software that then does raytracing on it. And the old software is setting up some STRONG restrictions on functions. However I seem to have found a workaround. As soon as I get approval on the figures I'll post my current solution.  
> **username_1**: Yes but if you could tell what the old ray tracer is then we can come up with better solutions. I mean first you tell use it has to be torus and sphere cylinder etc. than you relax it to hull and Malinowski functions. Neither one of those alone are perfect solutions. But given artificial restrictions that are there because you think you are restricted in this way is not effective communication.   B-Rep is for most part CSG.  
> **username_0**: You are indeed correct. The final object must be constructed in Craig E. Kolb's Rayshade program and it must be inputted as a text file. I am still not allowed to use commands such as Hull or Minkowski since they are not available in Rayshade. I was looking for a way to simulate them. Up to now I've had (in my opinion) relative success by taking three projections of the objects and then intersecting them.   Documentation about Rayshade can be found in here: http://graphics.stanford.edu/~cek/rayshade/doc/guide/guide.html  
> **username_1**: Howabout using sweptsph that gives you quite some options.  
> **username_0**: It turns out that intersecting the projections from three different views gives me an acceptable quality. I will check swepthsph if I need extra smoothness in the figures but for now the method I'm using is enough. Thank you very much for taking the time to help.  
> **username_1**: The reason nobody suggest the 3 projection boolean is because it does in fact not work for nearly any sensible case.  

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## 0 answers

