Find Closest UV to a Point

[homunculous1964]

Given a point in world space and a surface within the same scene, how can I find the closest point on the surface to that point in space? I want to be able to get the nearest point on that surface and the cooresponding uv coordinate. I want to do it with polygons, but if it's easier with NURBS, that will do.

I could not find a MEL command to find the nearest surface point (which surprises me because many commands have to find the closest uv point on a surface as part of its implementation, eg. normalConstraint). However, I found the MEL command "createNode closestPointOnSurface," which creates a node that should take in an input surface and a point in space, then give you the nearest uv. The problem is the attribute editor refuses to let me input anything into the space asking for a surface! How can I solve that?

I just want to be able to get the closest uv coordinate. Help, please!

[jeffd]

Hmmm.

When closestPointOnMesh was released for v4, it had a bunch of good docs on how to use it. It seems those haven't made it into the Maya5 docs anywhere.

closestPointOnMesh can also be used as a command not just as a node. do a "help closestPointOnmesh" in the script editor to get a better list of flags and usage as a command.

Here is an example of how I have used it in a script to retrieve the closest face to an arbitrary input point...

int $closestFace = closestPointOnMesh -ip $vertex\_x $vertex\_y $vertex\_z -q -f $selectedObject;

The -ip flag is where I put in the xyz location.
-q puts me in query mode
-f tells it to return a face index number
$selectedObject is the object I want the point on.

There are also flags for querying the closest point's UV value.

If you need I also have a little bit of code which takes this closest face and finds the closest actual vert, if you need it.

Hope this helps...
--JeffD

[homunculous1964]

Thank-you very much for the reply! That's exactly what I need! The problem is that when I type in "help closestPointOnMesh" in the script editor, it says, "There is not command named 'closestPointOnMesh.'" The command also creates an error when I try to use it. I have Maya5 Unlimited version. Any ideas why that would be?

It's frustrating that it's not there because that is perfect for what I need!

[jeffd]

Yep. For whatever reason, this very useful tool doesn't auto load so you need to go to the plug-in manager and load the closestPointOnMesh.mll and set it to auto load for future use.

Sorry, I should have mentioned this last time. In fact, in my script which uses this, I do a check that it is loaded...

int $pluginLoaded = pluginInfo -q -l closestPointOnMesh.mll;
if (!$pluginLoaded)
error "You must load the plugin closestPointOnMesh.mll!";

--JeffD

[homunculous1964]

closestPointOnMesh.mll is not in the plugins with my version of Maya (I cannot find it in files and folders, anyway). Is there anywhere it's available for download?

[homunculous1964]

I did find a Visual C++ file for building the .mll file. I tried compiling it, but there are some errors linking:

Linking...
LINK : fatal error LNK1104: cannot open file "Foundationd.lib"
Error executing link.exe.

closestPointOnCurve.mll - 1 error(s), 0 warning(s)

Any experience on this? How can I solve this error? I cannot find a Foundationd.lib

[jeffd]

Whoops. My bad again. I thought for sure that these plug-ins had been rolled into the core package for 5.0. You need to get the BonusTools pack of scripts and plug-ins. The plug-in is with all of that stuff. There at least another dozen useful things in that pack also.

--JeffD

[homunculous1964]

Thankyou thankyou Jeff!! You have been most helpful. I can take it from here to search out the plugin.

If you or anyone does not mind one more question, does the BonusTools pack come with Maya or does it need to be purchased somewhere?

Thanks again!

[jeffd]

It is a free download from the Alias site.

--JeffD