selecting vertex based off its color

[James Kim]

Hi there,

I'm trying to figure out how to select a vertex based off its color value.

so far this is what i have but 

vNum = cmds.polyEvaluate(v=True)

vertexList = cmds.ls('pCube1.vtx[:]',flatten=True)

for i in vertexList:

if cmds.polyColorPerVertex(r=0.5):

cmds.select(i)

any suggestions? Thank you

[Michael Boon]

polyColorPerVertex returns a value, so you need to compare that to 0.5.

You'll want something like:

for v in vertexList:
    if cmds.polyColorPerVertex(v, q=True, r=True) == [0.5]:
        cmds.select(v, add=True)

Also, polyColorPerVertex gives a RuntimeError sometimes, I think when the vertex has no color, so you'll want to handle that too.

[James Kim]

Thank you so much! It worked!

[James Kim]

So i've come across an interesting problem. 

it seems maya can only select vertexes with color index 1.0 or 0.0. i cannot seem to get the code to select from any ranges inbetween. I've tried the other flags on the polyColorPerVertex and nothing seems to work.

as an example

import maya.cmds as cmds

sel = cmds.ls(sl=True)[0]

vNum = cmds.polyEvaluate(v=True)

vList = cmds.ls('pPlane1.vtx[:]', flatten = True)

for i in vList:

if cmds.polyColorPerVertex(i, q=True, r=True)==[1.0]:

cmds.select(i,add=True)

will select all the verts with color info 1.0

but

import maya.cmds as cmds

sel = cmds.ls(sl=True)[0]

vNum = cmds.polyEvaluate(v=True)

vList = cmds.ls('pPlane1.vtx[:]', flatten = True)

for i in vList:

if cmds.polyColorPerVertex(i, q=True, r=True)==[.456]:

cmds.select(i,add=True)

will give me nothing. 

Thank you

[Michael and Amanda]

I'm off work for a couple of weeks so can't verify anything, but you can do some checks to find out the cause.

Each time through your loop, instead of using polyColorPerVertex in the if statement, assign its result to a variable, then print it out, then use it in the if statement. Something like:

col = cmds.polyColorPerVertex(i, q=True, r=True)[0]

print col, col == 0.456

if col == 0.456:

    etc

That will tell you if you're actually getting the colours you expect, and also tell you if Python thinks the value is close enough to 0.456 that it considers them equal. It may be that you need to check if col > 0.456-0.001 and col < 0.456+0.001 because it might be really close but not quite equal.

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[James Kim]

Thats what i thought so i used the actual query value before but it still wouldnt work. I'll try your method as well and see the results. 

[Marcus Ottosson]

if cmds.polyColorPerVertex(i, q=True, r=True)==[.456]:

I suspect a precision problem, where e.g. [0.4560001] == [0.4560002] would return False. Try clamping it before comparing.

if map(round, cmds.polyColorPerVertex(i, q=True, r=True), [2]) == map(round, [0.456], [2]):

This’d compare the two values using two decimal places. round is a native Python operator, that takes two values, round(0.123, 2) and returns the first at the second number of decimal places, in this case 0.12. You could also int(value * 100) as an alternative.

On Sun, 23 Dec 2018 at 10:53, James Kim <james...@gmail.com> wrote:

Thats what i thought so i used the actual query value before but it still wouldnt work. I'll try your method as well and see the results. 

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