Custom selection tool

ArunYoganandan

Hi All,

As some of you might be familiar, I'm building an immersive version of Sketchup. One of the custom tools I'm building is a 3D selection tool. i.e, you select objects that lie within a cuboid in 3D rather than a rectangle drawn in screen space.

The selection algorithm basically walks through all the entities in the active_model.entities and checks to see if the bounds of the entity are intersecting/contained with that of the selection cube or not.

One of the difficulties I'm facing is with curved surfaces like a cylinder. My algorithm seems to be selecting every edge on curved surfaces, rather than the just the surface.

Here is a screenshot. To the left is the effect of using Sketchup's native selection tool and to the right is the one I wrote. SU's native tool selects 72 entities, while mine selects 96. On comparing the entities, the extra ones I have are edges on the curved surface.

I have two questions.

a) Is there a way to differentiate these edges on curved surfaces from others, so I don't include them in selection.

b) My performance is really slow with curved surfaces. Does SU have a region selection mechanism? or is there a better algorithm I can use than what I described above. I can post code snippets if needed.

Thanks in advance for your help
Arun

sdmitch

As for question 1,the "dashed" lines defining the edges of the faces that make up the surface should be excludable by testing edge.soft? and edge.smooth? and ignoring it if either is true.

As for question 2, the only thing in the SU API related to this is the Geom.point_in_polygon_2D which is useless in this case. If you would care to post the code you are currently using, maybe I or someone could offer an openion on what might be done to speed things up.

Dan Rathbun

One thing is you should be iterating the active_model.active_entities collection, to be sure and only select items in the current editing context. (Which could be the entire model.)

ArunYoganandan

@sdmitch said:

As for question 1,the "dashed" lines defining the edges of the faces that make up the surface should be excludable by testing edge.soft? and edge.smooth? and ignoring it if either is true.

As for question 2, the only thing in the SU API related to this is the Geom.point_in_polygon_2D which is useless in this case. If you would care to post the code you are currently using, maybe I or someone could offer an openion on what might be done to speed things up.

edge.soft? and edge.smooth? did get rid of the dashed lines. Thanks so much!

Here is the function I'm using

		def selectInVolume( view)
	
		#Add the corners from the 3D selection box into a selection volume
		selectionVolumeBBox = Geom;;BoundingBox.new
		selectionVolumeBBox.add @corner1
		selectionVolumeBBox.add @corner2
		selectionVolumeBBox.add @corner3
		selectionVolumeBBox.add @corner4
		selectionVolumeBBox.add @corner5
		selectionVolumeBBox.add @corner6
		selectionVolumeBBox.add @corner7
		selectionVolumeBBox.add @corner8
		
		
		sel = Sketchup.active_model.selection
		
		universalList = Sketchup.active_model.entities
		
		universalList = universalList.to_a - $unSelectableList
		
		universalList.each{ |b|

			if(b.class != NilClass )

				if(b.visible? == true)
				
					allCornersLieWithin = true
					boundBoxObject2D = b.bounds
					
					resultantboundBox =  boundBoxObject2D.intersect selectionVolumeBBox
					status = resultantboundBox.empty?
					
					if(status)
					
					else
						if(selectionVolumeBBox.contains?(b.bounds.center))
						
							for i in 0..(7)
								pt = (b.bounds.corner(i))

								if(!selectionVolumeBBox.contains?(pt))
									allCornersLieWithin = false
									break
								end	
							end
	
							if(allCornersLieWithin == true)
									sel.add b
							end
						
						else
							#if center doesnt lie within, then no point in checking for corners. the object clearly is not completely within
						end
					end

				
				end

			end				
		}
	
	end

ArunYoganandan

@dan rathbun said:

One thing is you should be iterating the active_model.active_entities collection, to be sure and only select items in the current editing context. (Which could be the entire model.)

Thanks for the suggestion. I revised my code to active_entities. Doesn't seem to make much of a difference in performance right now, but I see your point as to how it could in other situations.

sdmitch

Using the BoundingBox certainly works as long as the selection box is not rotated which will cause BoundingBox to be much larger than the selection box.

I see no reason why the selection process should be any slower on a curved surface. It should only matter how many total entities there are in the model.

ArunYoganandan

@sdmitch said:

Using the BoundingBox certainly works as long as the selection box is not rotated which will cause BoundingBox to be much larger than the selection box.

I see no reason why the selection process should be any slower on a curved surface. It should only matter how many total entities there are in the model.

Yea. That is the same thing I'm confused about as well. Unless SU has a way of selecting the cylindrical surface as one unit or a collection rather than add each face of the curved surface one after the other(which is what my code does). Also, all my conditionals could be slowing things down as well.

The selection box is axis aligned, so the they bounding box and the selection box should pretty much be the same size.