Parasolid kernel

Dear McNeel,
I use Rhinoceros since it was created 25 years ago.
I started my cad design experience with Autocad 2.6, then I moved to Rhinoceros and I partecipated to the beta testing when the program was free.
I daily use Rhinoceros (and I love it) but I follow all the new technologies around the cad-design world.
Sometimes I use Spaceclaim to repair 3d models. Some clients of mine use Siemens NX and I create lightweight models from exported parasolid files.
After 25 years of Rhinoceros use, I decided to ask you: Why don’t you want to add the parasolid kernel?
You have 30 years of programming experience, why don’t you develop your direct modeling kernel?
Why do I have to spend a lot of money to buy Solidworks or Spaceclaim to convert parasolid files?
I always dreamed for a direct modeling feature in Rhinoceros.
Sometimes, after having created complex shapes, I have to use Spaceclaim to repair the model or to delete a fillet.
I know that the parasolid license has a cost but I prefer to invest my money for McNeel instead to purchase other programs.
I can’t understand how the person (developer) behind Plasticity was able in just one year to implement the 90% of the parasolid features inside his app. Probably he is a genius. He has created what McNeel created 25 years ago…a new milestone.
I can’t imagine what he can do in 2-3 years…
If McNeel needs more money for a Rhinoceros version with direct modeling features I’m willing to pay more.



Most of our users are not.

My guess is adding the parasolid kernel to Rhino would require a major rework of the Rhino code, with the probability of numerous bugs and unintended consequences. That would be in addition to the licensing cost.

Pro users can afford more than 1.000 euros for a 3d app…

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Let me rephrase this question you are asking McNeel, so you better understand it, because they already understand it very well:

“Why do you own this old Honda that takes you, and us, everywhere, when you could be leasing a Mercedes S-Class? A few people like me will be happy to pitch in for the gas when we take a few rides a year with you!”


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What does that question even means?

Parametric software surely have huge amount of code and know-how.
Rhino installer is 300MB, installed is 600MB.
Programs like NX easily need 10+ GB!

Rhino have its wonderful, incredible, magic code that can fit in half of a CD… but that code can run behind and “breath on the neck” of dozens of other hugely bigger software … and often even win!

After building up 300MB in 25 years (as you say) you ask: “Why you don’t write some other 10x code?” … to compete against giants? In their own field/specialization?

Might as well ask Norway to build its own space industry to compete with NASA/CNSA !

I am not informed and I am totally speaking out of ignorance, but I guess McNeel aim to compete by pushing Rhino strong points…
Starting developing a parametric core/“kernel” today would mean slow down developing the other parts that made Rhino what is today and let competitors eat the market…

My phone has 512 GB of ram…
I don’t want to have the same NX capabilities, I don’t want a parametric modeler.
I need only some direct modeling features that we can find in Inspire Studio, Form-Z, Shapr3D, Plasticity.
These modelers aren’t expensive.
As I wrote before, I’m a Rhinoceros user for 25 years. I also used Solidworks, Solidedge, Fusion360 and Spaceclaim.
Currently I’m using Spaceclaim to repair some complex 3d models created in Rhinoceros through many boolean operations. I can delete holes, fillets, chamfers, move/rotate the faces without destroy the model. In Rhinoceros we have to rebuild the model from the start.
On the market there are other direct modeling kernels, cheaper than the parasolid.
Regarding the car I prefer to drive faster with a Ferrari Purosangue than slow with a Honda…
My clients don’t know what tools I’m using, they need asap my 3d designs.

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As others have mentioned, the problem is not necessarily the potential extra cost - assuming it could be a paid add-on, nor really the file size - which doesn’t matter all that much these days.

The main problem is - as mentioned above by @davidcockey - would be the integration of the parasolid kernel to work alongside and with Rhino’s native geometry engine. This could potentially take a long time and lots of work to figure out and get working correctly - and those costs would need to be borne by the probably limited number of users of the add-on. Or they would have to be passed on to all, meaning higher prices or lower profits.

However, in my mind, it is not necessarily the economics of the operation that are the most problematic. Assuming you have parasolid kernel created/controlled objects coexisting with Rhino kernel created/controlled objects in a Rhino document - how do they interact? Being able to go back and forth is probably the stuff that nightmares are made from.

Also consider this: Parasolid is a 3rd party library. As such Rhino would become (partially) dependent on what that third party develops and decides what to do with their product (including pricing!). If there are bugs or limitations one has to wait until the third party decides to fix them or not and release a new version. New versions could potentially break some existing functionality when integrated into Rhino.

Right now McNeel has pretty much complete control over its geometric engine. This allows developers to fix bugs and add new features as fast as possible without relying on an outside entity. It allows McNeel to determine its own design direction. This independence is (IMO) a large part of what makes Rhino what it is today.


You confuse RAM with SSD.

geometric modeling kernels:


This makes sense IMHO.


It’s sad to see Plasticity having signed a contract, when the narrative of the war shown to the public is probably not the whole truth.

Within a few years the narrative will probably be much different.

Hopefully the contract and direction wont be too big of a tangent for very many years.

Parasolid is probably fine though. But seems kind of like a trap for users to become hooked.

I am not a programmer and maybe what I say isn’t correct but showing the video from Plasticity “what is a geometric kernel” I’ve seen the same software work with 3 different kernels. So I suppose, and I said probably I am wrong, that it’s not impossible to implement it. About the cost again I haven’t any knowledge, but from the plasticity side, I saw that it will not create a huge difference. The most expensive version of plasticity is about 300 dollars. I am sure most of the rhino users, if not all, will be happy to pay more for an implementation like this. I think that long term that maybe reduce the cost for McNeel.
I feel that it’s more like an obsession from Mcneel’s side. They want everything to be in-house. But I think if they always try to invest in the wheel they will miss the bus.

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That is not true and it’s easy to investigate it.

I’ve already asked the Plasticity developer to create a plugin similar to the one available for Blender.
I currently use Spaceclaim to repair some Rhino geometries, unfortunately it uses only the Rhino 5 format, the plugin was developed before that Ansys acquired Spaceclaim.
Rhino 8 Beta works good on some push/pull transformations but there is no way to have curved surfaces controls or push/pull edges to create fillets and chamfers.
I think the worst part of the Rhino kernel is the hidden lines command. I always use Spaceclaim to create 2d drawings from Rhino 3d models. It’s precise for sections, details, automatic hatching.
Probably the Rhino push/pull command is the start point for a new realtime modeling kernel developed by the McNeel team.
Fingers crossed.


if Rhino were equipped with an interactive tool (like push and pull) to create fillets/chamfers it would be a blast!
Easier said than done.


Go for it, we’d love to see what you come up with.

We’ll compare your data with our decades of sales and pricing research and data and happily see where the opportunities lie. Bob is remarkably gifted at looking at detailed financial info and analysis.

If it comes back we can actually double or triple the price of Rhino, can we tell everyone it’s because of you? :wink:


This looks like a job for @Joshua_Kennedy the wizard behind push pull…

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Personally I love McNeel’s philosophy of having everything independent. You can check out latest news on game engines and see how depending on a non-open source engine can turn out badly. From user persective it’s easy to crtitisize these decisions, because you are not the one taking the risk, but McNeel is.


you need to double or triple the price for adding Parasolid kernel? How plasticity price 99 dollar for the indie version and 299 for the full version for a product with this kernel?

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The same way zbrush was dirt cheap for years then sold to Maxon and then screwed it’s entire user base 3 months after the sale (me included) …

They are not making software, they are making a software company to sell. You are confused about what they are actually making. You are not a customer, you are an asset to be sold later to a higher bidder. The low prices you are getting now will go up after they sell sometime down the road.

I’m more than happy to have this discussion when Plasticity celebrates their 25th anniversary of continuous operation like we are doing this year.