closestPointOnMesh to edges

[djtomservo]

I've been using closestPointOnMesh recently and I noticed that while it returns faces, it doesn't return any other component type. Does anyone know how to take a point and see what edge it's closest to or what edge it lies on?

[jeffd]

I have a script that I use closestPointOnMesh to get to a vertex. Basically, I get the face then I iterate through that faces verts to find which is closest. Possibly the same approach could work for edges.

--JeffD

[naughty]

let's have it then Jeff!!

[jeffd]

Heh heh

Well, it is a small part of a much larger script. And, of course, I have it cleanly coded into its own proc, right? Um....oops.

I have a pretty readable piece of code I could post, but it would probably be just as easy to write it yourself. Get the verts, distance check each, keep the closest one.

Unfortunately, the original question was asking for the closest edge, which is obviously a much harder problem since an edge is not a single point.

--JeffD

[naughty]

Well I wrote a script called "snapVertexToNearest" (I'm sure you can guess what it does) but, although it works, it has to check your selected verts against every other vertex in the scene and this can take upwards of 5 minutes on some vertex-heavy scenes... I can't think of a way to just check those vertices within a smaller, limited distance away... without having to do the whole checking process again on every vertex in the scene...?

does that make sense? I want to reduce my check list of verts before I start checking which is closest.. any ideas how I do this fast (and accurately)?

at present, I'm using the distanceBetween node and changing it's inputs between every combination of vertices in the scene in a for..loop. Could I use the closestPointOnSurface node in some way instead? (I got the impression it was a NURBS thing only...)

:nathaN

[jeffd]

Definitely, you should try using closestPointOnMesh. I used it for the same reason. This guaranteed that, on a triangulated model, I would never have to check more than three verts. Here is a piece of code ripped from my script...

////////////////////
//Get the verts of closest face to this point
int $closestFace = closestPointOnMesh -ip $vertexInDataSplitFloat[0] $vertexInDataSplitFloat[1] $vertexInDataSplitFloat[2] -q -f $selectedObject;
select -r ($selectedObject + ".f[" + $closestFace + "]");
PolySelectConvert 3;
string $closeVerts[] = ls -sl -fl -l;

	//Which vert is closest? -- simple distance check on each
	string $closestVertName = "";
	float $closestVertPos[2];
	float $closestDistance = 1; //arbitrarily high number to ensure the first distance check succeeds

	for ($modelVert in $closeVerts)
	{
		//Get position of modelVert
		float $modelVertPos[] = `pointPosition -w $modelVert`;

		//Distance to data point
		float $x = ($modelVertPos[0] - $vertexInDataSplitFloat[0]);
		float $y = ($modelVertPos[1] - $vertexInDataSplitFloat[1]);
		float $z = ($modelVertPos[2] - $vertexInDataSplitFloat[2]);
		float $testedDistance = sqrt (($x*$x) + ($y*$y) + ($z*$z));

		if ($testedDistance < $vertMatchTolerance)
		{
			if ($testedDistance < $closestDistance)
			{
				$closestDistance = $testedDistance;
				$closestVertName = $modelVert;
				$closestVertPos = $modelVertPos;													
			}

			//DEBUG
			//print ("tested distance = " + $testedDistance + "n");
			//print ("closest distance = " + $closestDistance + "n");		
		}
		//DEBUG
		//else
			//print "---Failed tolerance test---n";
	}  //end for-in $closeVerts

///////////////////////////////

Hopefully it will be readable for you. I didn't bother changing var names and you can see I am also doing a distance tolerance check in there. Just ping me with any other questions you might have about it.

--JeffD

[djtomservo]

Hmm. . .have you maybe thought about doing something like expanding the selection first? Say have the script take the vert you select, then expand the selection and just use whatever that returns as the test set?

[naughty]

unfortunately my script's primary purpose is to ensure the exit vertices of one room align exactly with the entrance point to the next room. so the verts I want to snap to will always belong to a different, unspecified object.
There isn't much practical use for snapping a vertex to it's nearest in the same object (in the context of my script and our working practices I mean).

consequently I've realised that closestPointOnMesh is not going to help my script's speed either...

If I did want to do that though, expanding the selection would be the most sensible first step you're right.

[warpcat]

Little OT but... am I missing something? I can't seem to find the "closestPointOnMesh" mel command. Is it generated through a plugin? Was it in 4.5 and not 5.0? Thanks.

[macaronikazoo]

its a plugin that comes with the bonus game tools. i haven't looked to see if its standard in maya 5 yet, but yeah, download the bonus game tools to get it.