[Sidefx-houdini-list] making points to represent prims and connecting them.

Robert Kelly isstuff at gmail.com
Sun Oct 2 02:59:41 EDT 2011


...and now there is a file attached to the post.

On 1 October 2011 10:16, Robert Kelly <isstuff at gmail.com> wrote:
> I have remade compute dual!
>
> Pro Tip!
> don't remake existing tools if your short on time.
>
> when I first looked at using compute dual at making 1 point per
> primitive I missed the option to not pre triangulate the mesh so it
> looked like compute dual was not doing what i needed. So i rebuilt
> compute dual.
>
> Slower, More Complicated, Less Better!
>
> But you can probably learn a thing or two from my experiment.
>
> check it out here
>
> http://forums.odforce.net/index.php?/topic/14040-how-compute-dual-can-be-remade/
>
> On 1 October 2011 09:13, Robert Kelly <isstuff at gmail.com> wrote:
>> Yes. I took a grid and poly reduced it a little (don't pre triangulate ) to make a mess of quads and tris.
>>
>> The divide sop is all about the points, you end up with one prim for every corner between prims. you could tweak this mesh by joining some of the edges of the  Compute Dual but that is more messy than building the mesh your self. I came up with a solution last night and will build it into an asset and release it on the exchange.
>>
>> It isn't tooo slow the slowest part is the primneighbours(surface_node, prim_num, num_shared_pts) expression asking every prim who its neighbors are sharing 2 points with the prim in question. Every thing else that makes the mesh combined is faster than that node. but it will be on exchange soon enough and everyone can use / pick it apart. and maybe someday there will be a new option beside divide to do this.
>>
>> After making it i realize most of the problems can be solved with an Attrib Promote. but there will be top sop stuff that you can do with neighbor points which will effectively be  neighbor  prims that will make it useful. if you mesh moves you dont have to rebuild the mesh every frame just distort it into position.
>>
>>
>> anyway i will get this thing on line so you all can see what i am talking about.
>>
>> On 30/09/2011, at 11:45 PM, François Duchesneau wrote:
>>
>>> Hey Rob,
>>>
>>> but if you use the divide sop with Compute Dual, you've got the same number of points as you had the number of primitives. Is it because your geometry is more complex than the one I'm trying with?
>>>
>>> François
>>>
>>> Robert Kelly wrote:
>>>> I am looking to manipulate some primitive attributes as if they were point attributes in a top sop and i would like to smooth them and do other connectivity related operations to them. I have the need trick of converting primitives to points with convert_sop using "convert to circles" so i have a point per primitive. But the connectivity between the primitives is the tricky one. I need a line per edge.
>>>>
>>>> The solution probably looks like a divide sop with compute dual but i need the same number of points as there were primitives for this to be the solution.
>>>>
>>>> Any ideas?
>>>>
>>>> Maybe this is something that is worthy of a RFE think of all the tricks you could do with this. It could be called mesh premote
>>>> Robert.
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>>
>



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