How to get circumferential grids by selecting a node using TCL
Altair EmployeeHi,
I have a meshed cylinder (2d) on which i want to give an option to select a node to user. Once the node is selected, and clicked on proceed button it should display all the circumferential grids having a user defined number to the grids. Let's say i select a grid having ID as 122. Now, i want to display all the circumferential grid starting from 123 on the same station location where user has picked the node. I want to do it using TCL/ TK.
Thanks
Answers
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Is that node located on free edge?
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Altair Forum User said:
Is that node located on free edge?
It's located on the circumference anywhere the user selects.
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It's not easy I think
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Do the nodes form a circle or an ellip possibly?
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You said a cylinder so the nodes will be planar
You can select them by createmark 'on plane'
You have to detect cylinder axis vector, with base node is selected one, will define a plane, as args of createmark
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Altair Forum User said:
You said a cylinder so the nodes will be planar
You can select them by createmark 'on plane'
You have to detect cylinder axis vector, with base node is selected one, will define a plane, as args of createmark
I think there is a bit of confusion here. Refer the image, as can be seen i have a node selected using '*createentitypanel node'. Now, as the black circles shows circumferential node locations on the same axial station. I want to get their IDs as stated in the problem. Or just if i can get any info for all the nodes on that circumference.
<?xml version="1.0" encoding="UTF-8"?>
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Yeh. I do talk that
You can get ids by createmark 'on plane'
Can you fetch axis vector of the cylinder?
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Altair Forum User said:
Yeh. I do talk that
You can get ids by createmark 'on plane'
Can you fetch axis vector of the cylinder?
I'm not sure about it. I'll need to try that. But how would you suggest the approaches if i can fetch the axis vector or if i can not fetch the axis vector?
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Another way: get normal vector at the white node, get 2 intersected points of this with cylynder, get mid point, then get closest nodes to midpoint
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You can fetch axis vector by surf lines, one of them is parallel to axis
If noone is, create parametric lines which will be parallel to axis
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Altair Forum User said:
Another way: get normal vector at the white node, get 2 intersected points of this with cylynder, get mid point, then get closest nodes to midpoint
Which APIs i can use to get normal vector and do the following?
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use hm_getsurfacenormal nodes $your_selected_nodeid
the node must be associated to surface.
if the node is not associated, use hm_getsurfacenormalatcoordinate
to find intersection points between normal vector and surf, use *nodecreateatplaneintersection
and to find mid node of 2 intersected nodes, use *createnodesbetweennodes
to find nodes closest to the mid node, use hm_getclosestnode
I think it is better to get it by *createmark 'on plane'
like this:
*createmarkpanel nodes 1 'Pick a node on cylinder:' set Node1 [hm_getmark nodes 1] if {[hm_entityinfo exist nodes $Node1]} { set SurfId [hm_getentityvalue nodes $Node1 surfaceid 0] if {[hm_entityinfo exist surfs $SurfId]} { *createmark lines 1 'by surface' $SurfId foreach LineId [hm_getmark lines 1] { if {[hm_getlinetype]==2} { lassign [hm_getlinetgstartpoint $LineId] Vx Vy Vz eval *createmark nodes 1 {'on plane'} [expr [hm_nodevalue $Node1]] $Vx $Vy $Vz $Tolerance 1 1 *createmark nodes 2 displayed *markintersection nodes 1 nodes 2 if {[hm_marklength nodes 1]} { *numbersmark nodes 1 1 } *clearmarkall 1; *clearmarkall 2; break } } } }
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Altair Forum User said:
use hm_getsurfacenormal nodes $your_selected_nodeid
the node must be associated to surface.
if the node is not associated, use hm_getsurfacenormalatcoordinate
to find intersection points between normal vector and surf, use *nodecreateatplaneintersection
and to find mid node of 2 intersected nodes, use *createnodesbetweennodes
to find nodes closest to the mid node, use hm_getclosestnode
I think it is better to get it by *createmark 'on plane'
like this:
*createmarkpanel nodes 1 'Pick a node on cylinder:' set Node1 [hm_getmark nodes 1] if {[hm_entityinfo exist nodes $Node1]} { set SurfId [hm_getentityvalue nodes $Node1 surfaceid 0] if {[hm_entityinfo exist surfs $SurfId]} { *createmark lines 1 'by surface' $SurfId foreach LineId [hm_getmark lines 1] { if {[hm_getlinetype]==2} { lassign [hm_getlinetgstartpoint $LineId] Vx Vy Vz eval *createmark nodes 1 {'on plane'} [expr [hm_nodevalue $Node1]] $Vx $Vy $Vz $Tolerance 1 1 *createmark nodes 2 displayed *markintersection nodes 1 nodes 2 if {[hm_marklength nodes 1]} { *numbersmark nodes 1 1 } *clearmarkall 1; *clearmarkall 2; break } } } }
What if there are no surfaces and lines in the model. There are only elements and nodes. any suggestion?
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It is even easier,
/emoticons/default_rolleyes.gif' title=':rolleyes:' /> from free edges, find elems 'by adjacent' until selected elems contain $your_selected_node
Within each searching loop, save old nodes and subtract them at next search to get expected nodes
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Altair Forum User said:
It is even easier,
Within each searching loop, save old nodes and subtract them at next search to get expected nodes
Can you please elaborate using code? i am unable to write the logic...
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Like this
-select a node on comp
-find edges of comp
-turn off comp
-get edge elem list
-createmark 1 edge elem
-appendmark 1 by attached
-turn on comp
-loop:
-createmark nodes by elem mark 1
- check mark if contain selected node
-markdifference nodes 1 nodes 2
-return nodes in mark 1
-else
-createmark nodes 2 by elems in mark 1
-append mark elems 1 by adjacent
-endloop
Is that enough logic?
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Altair Forum User said:
Like this
-select a node on comp
-find edges of comp
-turn off comp
-get edge elem list
-createmark 1 edge elem
-appendmark 1 by attached
-turn on comp
-loop:
-createmark nodes by elem mark 1
- check mark if contain selected node
-markdifference nodes 1 nodes 2
-return nodes in mark 1
-else
-createmark nodes 2 by elems in mark 1
-append mark elems 1 by adjacent
-endloop
Is that enough logic?
What if the selected node is not on free edge? what if it's somewhere in the middle?
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If it is in middle, the loop will find it
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Altair Forum User said:
If it is in middle, the loop will find it
Hi Tinh,
Thanks for your help. I'll need a little different thing now as per change in requirement.
1. Before iterating i need to find, whether the node is created using Cartesian coordinates or cylindrical!
a. If it's a cylindrical system, then i should follow the above approach and then define coincident grids.
b. else if it's Cartesian i need to define RBE elements.
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I don't understand.
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Altair Forum User said:
I don't understand.
See if i query for a selected node, i get the coordinates x,y,z. But i want to check if these nodes were created using cylindrical coordinate system (r,theta,Z)[local CSYS] or Cartesian (x,y,z) [global WCS]. and then if it is the second one, then do the above steps, means to select all circumferential grids.
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So you ought to ask 'how to check input system type of a node'
You had node id, then:
set UseCartesian [expr ![hm_getentityvalue nodes $NodeId inputsystem.type 0]]
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Altair Forum User said:
So you ought to ask 'how to check input system type of a node'
You had node id, then:
set UseCartesian [expr ![hm_getentityvalue nodes $NodeId inputsystem.type 0]]
Yes exactly. Thanks for your help.
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Hi Tinh,
For the above discussion, if i want to get all the nodes in circumference where user will select a single node (having local r,t,z) values, how can i write the logic?
I tried this way,
1. Select a node, get r,t,z values.
2. Write a loop varying t value from 0 to 360, keeping r and z same and use *getclosestnode and pass these 3 values to get the node lying on these passed coordinates.
Problems: 1. hm_getclosestnode doesn't give me the exact node for which the coordinates were passed. (Not sure which closest node it finds)
2. I don't have idea which API should i use to get all those circumferential grids.
Can you please help me resolving my issue, i am new to customization. It'll also be helpful if we need to write any other logic.
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You have to define problem logically and do not change initial conditions
I guess you cannot do it because each time I guide you then you change assumption, i would not waste my time if you make clear at beginning
Now i want you to confirm what you want? what is input data that you have?
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Hi,
assumption:
- you have a cylindrical mesh (not have surf)
- mesh is quad only, equally
then, the proc below will select a circumference nodes base on a preselected node not lay on ends of cylinder
you can modify it to select nodes at 2 ends of cylinder (it's easy)
proc ::p_SelectCircumferentialNodes {{PreselectedNodeId {}}} { if {![hm_entityinfo exist nodes $PreselectedNodeId]} { *createmarkpanel nodes 1 'Pick a node on cylinder:' if {[hm_marklength nodes 1]!=1} return set PreselectedNodeId [hm_getmark nodes 1] } #we will find 4 quads attached to the node: *createmark elems 1 'by node' $PreselectedNodeId if {[hm_marklength elems 1]!=4} {*clearmarkall 1; return -code error 'not valid cylinder'} if {![string equal 104 [lsort -unique [hm_getmarkvalue elems 1 config 0]]]} {*clearmarkall 1; return -code error 'not valid cylinder'} lassign [hm_getmark elems 1] Elem1 Elem2 Elem3 Elem4 set nx1 [hm_getentityvalue elems $Elem1 normalx 0] set ny1 [hm_getentityvalue elems $Elem1 normaly 0] set nz1 [hm_getentityvalue elems $Elem1 normalz 0] set NodeList [hm_nodelist $Elem1] set nx 0; set ny 0; set nz 0 set TripleCosMin 1 foreach ElemId [list $Elem2 $Elem3 $Elem4] { if {[llength [lsort -unique [eval linsert [list $NodeList] end [hm_nodelist $ElemId]]]]==6} { set nx2 [hm_getentityvalue elems $ElemId normalx 0] set ny2 [hm_getentityvalue elems $ElemId normaly 0] set nz2 [hm_getentityvalue elems $ElemId normalz 0] set TripleCos [expr abs([hm_triplecos $nx1 $ny1 $nz1 $nx2 $ny2 $nz2])] if {$TripleCos<$TripleCosMin} { set TripleCosMin $TripleCos set nx $nx2 set ny $ny2 set nz $nz2 } } } if {!$nx&&!$ny&&!$nz} {*clearmarkall 1; return -code error 'not valid cylinder'} set vx [expr $ny1*$nz-$nz1*$ny] set vy [expr $nx1*$nz-$nz1*$nx] set vz [expr $nx1*$ny-$ny1*$nx] list $vx $vy $vz *appendmark elems 1 'by attached' *findmark elems 1 1 1 nodes 0 2 lassign [join [hm_nodevalue $PreselectedNodeId]] x y z *createmark nodes 1 'on plane' $x $y $z $vx $vy $vz 0.1 1 1 *markintersection nodes 1 nodes 2 hm_highlightmark nodes 1 h *clearmark nodes 2; *clearmark elems 1 }
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Altair Forum User said:
Hi,
assumption:
- you have a cylindrical mesh (not have surf)
- mesh is quad only, equally
then, the proc below will select a circumference nodes base on a preselected node not lay on ends of cylinder
you can modify it to select nodes at 2 ends of cylinder (it's easy)
proc ::p_SelectCircumferentialNodes {{PreselectedNodeId {}}} { if {![hm_entityinfo exist nodes $PreselectedNodeId]} { *createmarkpanel nodes 1 'Pick a node on cylinder:' if {[hm_marklength nodes 1]!=1} return set PreselectedNodeId [hm_getmark nodes 1] } #we will find 4 quads attached to the node: *createmark elems 1 'by node' $PreselectedNodeId if {[hm_marklength elems 1]!=4} {*clearmarkall 1; return -code error 'not valid cylinder'} if {![string equal 104 [lsort -unique [hm_getmarkvalue elems 1 config 0]]]} {*clearmarkall 1; return -code error 'not valid cylinder'} lassign [hm_getmark elems 1] Elem1 Elem2 Elem3 Elem4 set nx1 [hm_getentityvalue elems $Elem1 normalx 0] set ny1 [hm_getentityvalue elems $Elem1 normaly 0] set nz1 [hm_getentityvalue elems $Elem1 normalz 0] set NodeList [hm_nodelist $Elem1] set nx 0; set ny 0; set nz 0 set TripleCosMin 1 foreach ElemId [list $Elem2 $Elem3 $Elem4] { if {[llength [lsort -unique [eval linsert [list $NodeList] end [hm_nodelist $ElemId]]]]==6} { set nx2 [hm_getentityvalue elems $ElemId normalx 0] set ny2 [hm_getentityvalue elems $ElemId normaly 0] set nz2 [hm_getentityvalue elems $ElemId normalz 0] set TripleCos [expr abs([hm_triplecos $nx1 $ny1 $nz1 $nx2 $ny2 $nz2])] if {$TripleCos<$TripleCosMin} { set TripleCosMin $TripleCos set nx $nx2 set ny $ny2 set nz $nz2 } } } if {!$nx&&!$ny&&!$nz} {*clearmarkall 1; return -code error 'not valid cylinder'} set vx [expr $ny1*$nz-$nz1*$ny] set vy [expr $nx1*$nz-$nz1*$nx] set vz [expr $nx1*$ny-$ny1*$nx] list $vx $vy $vz *appendmark elems 1 'by attached' *findmark elems 1 1 1 nodes 0 2 lassign [join [hm_nodevalue $PreselectedNodeId]] x y z *createmark nodes 1 'on plane' $x $y $z $vx $vy $vz 0.1 1 1 *markintersection nodes 1 nodes 2 hm_highlightmark nodes 1 h *clearmark nodes 2; *clearmark elems 1 }
Hey Tinh,
I'm sorry about change in conditions. i'll make sure that doesn't happen again. The above code works perfectly, and selects all the nodes in the circumference.
Just two questions here,
1. How do i print a list of all these selected nodes so further i can work on them as per my requirement.
2. How can i bring in the concept of axial and radial tolerances, suppose some of the nodes are slightly away from axial location and radial location from the selected node's axial and radial location within these two tolerances provided by user.
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Hi,
To print out selected nodes:
::p_SelectCircumferentialNodes
set selected_nodes [hm_getmark nodes 1]
puts $selected_nodes
To select nodes with a tolerance, You can modify proc to
proc ::p_SelectCircumferentialNodes {tolerance} {
#........
*createmark nodes 1 'on plane' $x $y $z $vx $vy $vz $tolerance 1 1
#........
}
About radial tolerance, could you try moving a node radially and confirm it is sensitive or not? It will affect to element normals but i am not sure how to estimate it affection
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Altair Forum User said:
Hi,
To print out selected nodes:
::p_SelectCircumferentialNodes
set selected_nodes [hm_getmark nodes 1]
puts $selected_nodes
To select nodes with a tolerance, You can modify proc to
proc ::p_SelectCircumferentialNodes {tolerance} {
#........
*createmark nodes 1 'on plane' $x $y $z $vx $vy $vz $tolerance 1 1
#........
}
About radial tolerance, could you try moving a node radially and confirm it is sensitive or not? It will affect to element normals but i am not sure how to estimate it affection
Hey Tinh,
Will try that. Thanks a lot.
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Hi Tinh,
I've got a problem here. This code works fine only for few axial stations. Sometimes, it's just getting 2 or even single node on the circumference.
What could be the reason?
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