Sandbox - show only sections that are inside an object?


#1

Hi all

Sketchup newbie here. I’m trying to achieve a certain interaction between an object (a cone) and a sandbox which is probably a bit unusual. The best way to describe it is to imagine the cone is a light source and I only want to display the parts of the terrain that fall inside that cone. I want this to respond to changes I make as I edit the objects (eg changing the distance between them, editing the terrain with the Smoove tool etc etc.

Is there any sensible way to achieve what I’m after?

Some example images attached below. Thanks in advance for any tips!


#2

You could intersect the terrain object with the cone object, and then permanently remove the “outside” terrain.

But what you’re asking for is something that works more like the section planes, but is a section cone instead where you decide to hide everything inside or outside the cone. (In your case you wish to hide the outside.)

SketchUp only has section planes at this time, but you might be able to use two crossed section planes that could approximate the intersections where a cone intersects the terrain. The planes would cross at the apex point of the cone. You might even be able to use the cone for inferencing when placing the section planes.

The tricky issue is that only one section plane can be active for each entities context, at a time. So one of the planes could be in the model’s global entities context, the other plane you’d need to insert inside the terrain group’s entities context. [Double-click to enter into a group or component instance context.]


The only other way I can think of is to have a scriptlet you trigger by menu, that makes a unique copy of the terrain object, and does a boolean intersect or subtract, then hides the cone and full terrain group.

Whenever you make adjustments you run the menu command which deletes the old intersect, and makes a new one.


#3

Thanks Dan. A lot of this is way beyond my current understanding of the application, but maybe we can start with your first suggestion and see how far that gets me.

So, how would I go about intersecting the terrain with the cone as you suggest? I’ve not used the Intersect tool before, but I just tried grouping the sandbox and using the tool. When I hover the mouse over the sandbox I get a “Not a solid” tooltip. Is there something I should do to make the sandbox play nice with the intersect tool?

Thanks again


#4

I’m trying to follow what you intend to do but it isn’t clear to me.

But for better understanding please don’t use the word ‘Sandbox’ for the terrain (grouped or not) for ‘Sandbox’ is the name of one of SketchUp’s toolbars with various tools.

Could you give a few screenshots with several end results of what you are after?


#5

If I could get to the end result, I wouldn’t need to ask how to do it! :smile:

Sorry - I thought the term for a terrain object was Sandbox (since I started by using “create a sandbox from scratch”. What should I be calling it instead?

If you look at the lower of the two images above, the end result I’m after would be that all the terrain outside of the blue semi transparent area would be hidden. Only the terrain inside of the cone shape would be visible.


#6

It sounds as though you’re confusing the Solid Tools and the Intersect command
Learn about the Intersect command.


Then have a look at this example model.
Intersect Cone and TIN.skp (344.8 KB)


Intersect Command


#7

Geo, thanks a million - that was exactly what I needed to know! It had completely thrown me that there are two different commands both called Intersect (I’m a user interface designer by trade, and this kind of thing gives me nightmares…)

So, I’ve now managed to produce what I wanted:

Thanks to all for the help!


#8

see next quote, (what trows me off):

I thought you wanted an interactive (changable) cone intersection. Hence my asking for say two endresults. :smile: :smile:
You can do the intersect operation but it is for just one unchangable (direction-wise) result.

One intersect command (in the right click context menu) is the basic one that needs some cleaning up afterwards. It is also in the Free (Make) version of SketchUp.
The other intersect command is from one of the ‘Solid’ tools, only available in SketchUp Pro (or trial the first month). It does the cleaning up autamatically. It performs the operation on two intersecting SketchUp solids, not on just any intersecting geometry.


#9

Well “intersect” is a basic verb in geometric manipulation. The “Intersect Faces” command in SketchUp (on the right-click mouse context menu or the Edit menu,) is the original one. It came into being sometime before SketchUp v6.

The “Solid Tools” are Pro only boolean tools added in SketchUp 8. (Naturally there has to be an boolean Intersect tool in this feature set as well.) But these tools only work on “manifold solids” in SketchUp, not faces nor meshes.

:bulb:

So,… we aught to be referring to them differently. I think of them, as “Intersect” and “Solid Intersect.”


#10

Or maybe “Intersect Faces” and “Intersect Solids”?


#11

Perhaps, but I suspect the name of the original was changed at some point ~v8 ?


#12

Thanks guys. The main problem from my perspective was that when searching for “intersect” in the knowledge base, it wasn’t clear to me that the results were from two different tools. I happened to read the description of the solid version first, and that was what let to my initial post since I couldn’t get it to work.

I’m still in the free trial of Pro at the moment, so it’s worth me investigating the solid tools whilst I can. Having an interactive intersection would save me a lot of time for sure. So, on that basis is there an easy way I can convert a TIN to a solid?


#13

Taken that each of the four side curves of the TIN are curves in one plane:
From each four corners of the TIN draw an edge down to a large rectangular face underneath.
Connect their open/unattached endpoints to ccreate the four sides of the “terrain” box.
Delete what is left out of the bottom face, the outher four edges.
Tripple click your “terrain” box geometry and group it.

p.s.
1 and 2 should be drawn inside the terrain group to have SketchUp create the side faces.
No need to group the “terrain” box in the end. Since it was a group in the first place.


#14

Ah - I was working from your instructions prior to you adding the diagram. I may have misinterpreted what you said, but I drew a rectangle directly underneath the four corners. I then drew new rectangles across the four “walls”, and then did a right-click intersect with the TIN to remove the unwanted sections. I think I should have ended up with the same result you have in your example, but the shape intersect tool is still showing the “not a solid” tooltip:

I’ll upload the file in the next post…
(edit - maybe not… It’s 24MB)


#15

Forum file size limit is 3MB
Have you Purged the file? … Window > Model Info > Statistics > Purge Unused and then File > Save

If it’s still too big, then upload to the 3D Warehouse and post the link.
File > 3D Warehouse > Share Model


#16

In the end all geometry should be in one environment (editing contex of group or component).
Does your group have a bottom face?

A SketchUp Solid has no stray edges inside or outside the space of the “terrain” box and the should nod be any openings in the entire skin. Yust two simple rules that define all there is to it.

ThomThom has a plugin “Solid Inspector” that you can download and install from within SketchUp. See the button to Extention Warehouse.


#17

Okay guys - here’s the newly compressed file, weighing in at a slimline 930k :smile:
Terrain to solid.skp (930.4 KB)


#18

Click … Window > Outliner > Expand All (little blue arrow icon)
Notice the Grouped named ‘Terrain’ is nested inside the Group named ‘Terrain box’
Explode the Grouped named ‘Terrain’ and the Group named ‘Terrain box’ will then become a Solid.

A Solid is a single Group or Component … Not an assembly of Groups or Components.



#19

Cool - I now have my solid intersection:

Only question now is, how can I access the original objects again to edit them? I would want to play around with their relative positions and see the results in the intersection. I also need to hide the cone itself when producing some 2D output images for use in my project. I see that I now have a single “Intersection” group in the Outliner. If I explode this it explodes the intersection itself, but doesn’t give me access to the component parts.


#20

In the model you shared…
You built the geometry of the Terrain and made it into a SketchUp Entity called a Group.
Then you built the geometry of the Cone and made it a Group.
A Group is a unique entity. When you edit a Group, you are permanently editing the “original object”.

To preserve the original geometry of the Terrain Group and Cone Group, don’t edit them.
Simply move them off to the side and then make copies of them for use in each experiment.

OR

Make the original Terrain and Cone each into a SketchUp Entity called a Component.
Right Context Click on a Component > Save As to save a reusable copy.


Terrain to Solid - Components.skp (907.7 KB)


Components