Automatically create 3D model from intersection of volumes

[lois]

Negative-Positive-Intersection GH.3dm (1.8 MB) Hi,

I’m currently designing a 3D model from the “negative” spaces.

So instead of starting with walls, roofs and slabs, I’m starting with the negative spaces. Everything I design is the negative volume of the future result. I then have a positive volume (exterior), which then is subtracted by the negative space, creating a normal building. So my workflow goes as follows:

Negative > subtract Negative to Positive > Result volume with interiors

I’m currently working with Autocad 3D, since my volumes are very primitive. But I want to pass it on to Rhino and do something very specific, which I’m guessing Rhino is capable, but I don’t know how, I will describe it:

I want to keep designing from negatives, but I want to check out in real-time how the final result is becoming. So if I create a negative of a window, then I want to see a hole appearing in a separate model.

Maybe Grasshopper can do the job. For example, tell GH to copy all negative volumes (in-realtime) from a certain layer to a fixed position x distance from negative volumes (red), which will be superimposed with a positive model (green) of the exterior. Then tell it again to subtract those models to the positive model and create the final result. If real-time generation is not possible, at least a one-click version would be nice, because having to copy all volumes, joining them, then subtract them manually, every time is very time consuming. But I have no idea, how could I achieve this?

I’ve managed to do some GH work, but I don’t think it’s working. Why does Brep replicate the volumes? In which layer does the new GH breps go? Why the result appears transparent? (PS: volumes are 75m from each other)

I made a conceptual image to show what I want.
Thanks!!

Rhino+GH file: Negative-Positive-Intersection GH.3dm (1.8 MB)
GH file: GH file.gh (13.0 KB)
Autocad file: Positive-Negative-Intersection RF.dwg (3.9 MB)

(The model I show you in the image above is a simple example for demonstration only, not the actual model I’m working on, which has hundreds of intersecting volumes. At the moment I use Autocad, which is very basic, and this process is very slow if I need to check out how the positive final result is turning out to be. I must copy all negatives to the side, join them using union tool, then subtract it to the bounding volume. It’s a tedious process, so I rarely do it. I thought that Rhino could handle it so thinking of going to Rhino, but my Rhino knowledge is somewhat limited. I need some directions.)

[lois]

I had posted this in the Rhino section before, but I figured it made more sense if I posted in the Grasshopper section.

Automatically create 3D model from intersection of volumes

I found this video which explains part of what I want, but in a very simplified way. I think it’s a good start. https://www.youtube.com/watch?v=A-C2fYLS5G0 But I don’t know how to associate solids I have modeled in Rhino to the GH window. In this tutorial, they only show basic solids created within GH. My logic: Have Negative volumes, Positive volumes and Final result in separate layers (Layer N and layer P and layer F). The bounding working limits are a box with 20x20x20m. Any solid create…

[inno]

by moving the geometry to be subtracted 75 units along X axis I get this result:

but on the opposite side there is no visible effect:

by incrementing the X-movement to 76 units, I got this:

so I guess the workflow works, the only problem is that your geometry to be removed might be a little too small

I scaled it up by 5% on XY and here is the result:

Boolean.gh (478.1 KB)

generally speaking, for booleans subtraction to work correctly, don’t be afraid to be “abundant” with windows/door extension, make them even unreasonably longer than required

the most important thing is that those blue closed polysurfaces fully go through the green solid to create a succesfull boolean subtraction, any excess (in this case) doesn’t matter

[lois]

This is awesome! I’m slowly getting there, thanks for the help.
I have some questions:
Is the union operation necessary? I’d like to keep volumes separated.
Why the final result becomes transparent?

My current problem is that this is still not an automatic process. If I had a negative volume (red), then I must update the brep. This is why I to use breps from a whole layer and not by selecting multiple volumes, so that if I make a new volume in that layer, it automatically enters the GH operations.
I just don’t know how to achieve this.

EDIT: and i will make sure volumes are extruded over the limits

[inno]

you can use geometry pipeline components to directly input geometries from your layers

but you will always have to bake the GH results in Rhino (right click → Bake or through plugins)

@lois

Is the union operation necessary? I’d like to keep volumes separated.

about this, I think you mean the green Positive surfaces, yes it can be removed top get separate solids

[at first sight I thought I should also graft the A input of boolean difference, but I see it works ok regardless…]

Boolean_2.gh (10.3 KB)