Drop Geometry to Surface - Brainstorming for methods
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I'm not sure I understand what you want to do. Is the object a ComponentInstance?
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SmartDrop does this, so maybe there are some ideas to be drawn out from it.
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@jim said:
SmartDrop does this, so maybe there are some ideas to be drawn out from it.
SmartDrop deals with the bounding box of the instances - not the actual geometry.
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@martinrinehart said:
I'm not sure I understand what you want to do. Is the object a ComponentInstance?
Drop a
GrouporComponentInstancedownwards to the surface underneath by the actual geometry inside. -
An instance will 'rest' on the surface on three points [?].
Test all instance-vertices and their intersections with the surface - getting paired points.
Take the pair with the shortest distance between them.
We'll all that instance_pt0 and surface_pt0
Drop the instance vertically onto that surface-point.
Now retest [excluding the instance_pt0, that is now zero distance away].
If at least two of the other tested vertex-points are also zero distance away you do nothing more as the instance now rests on the surface.
If not then find the nearest matched pair again = instance_pt1 and surface_pt1.
This time you can't 'drop' the instance - you need to rotate it in 3D so this second vertex is touching the surface NEAR surface_pt1 [can actually be on it!].
To do that find the
angle = surface_pt0.vector_to(surface_pt1)angle_between(surface_pt0.vector_to(instance_pt1))
then the transformation to rotate the instance
axis = surface_pt0.vector_to(surface_pt1).cross(surface_pt0.vector_to(instance_pt1)) tr = Geom::Transformation.rotation(surface_pt0, axis, -angle) ### it's untested! or maybe +angle ??? instance.transform!(tr)
Now we have the instance rotated so that instance_pt0 and instance_pt1 both touch the surface...
Retest for nearest matched pair again - this time omitting the 2 vertices that touch the surface.
If there is at least one pair at zero distance do no more since you have three touching vertices; if not you need to re-rotate the instance again so that the third [nearest paired] vertex instance_pt2 again touches the surface NEAR the intersection at surface_pt2.
We need a pivot_point relative to surface_pt0 and surface_pt1...
vector01=surface_pt0.vector_to(surface_pt1) line01=[surface_pt0, vector01]
Find the point on line01 nearest surface_pt2
pivot_point = surface_pt2.project_to_line(line01)
Find the vectors from pivot_point to surface_pt2 and instance_pt2 and the angle between them
etctetcyawn!
'cross' the vectoro1 and the vector pivot_point.vector_to(surface_pt2) to get the rotation_axis.
again transform rotation the instance about pivot_point and rotation_axis by ang [or -ang???] and you should now have at least 3 points of contact ?????????????
I ran out of steam during the last few bits of code but you get the idea...........
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That's the thing - is brute force the only method? Testing all kinds of combinations?
Another issue: say you find three points that rest of the surface, now, it could be that they are very close together - say a chair's leg, you might end up with the chair resting on one foot and the remaining three legs in the air.
I guess we are then talking about taking mass and gravity into account - a whole lot more complicated?One way I was pondering about was - brute force iterate over various combinations and see in which combination the most points are closest to the surface ... ?
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not really sure how krill is doing this but maybe it's related?
http://forums.sketchucation.com/viewtopic.php?t=24676
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@unknownuser said:
not really sure how krill is doing this but maybe it's related?
http://forums.sketchucation.com/viewtopic.php?t=24676
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Never noticed that plugin before.
It's not doing what I'm trying to do though - but still interesting. It subdivides the selected group and makes it fit to the surface underneath. Nearly like vacuum forming. Could come in handy. -
@thomthom said:
I'm able to find the points facing the surface underneath - but then what?
Any clever way of fitting the object to the surface?There's a theread over at GG, where a guy and I discussed this a few days ago.
He had a different purpose of course.
contour seen from above
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Maybe kirill2008 Stick groups to mesh can inspire
http://forums.sketchucation.com/viewtopic.php?t=24676 -
@notareal said:
Maybe kirill2008 Stick groups to mesh can inspire
http://forums.sketchucation.com/viewtopic.php?t=24676Same as Jeff's link.
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