Author Topic: cylinder in different ucs  (Read 3004 times)

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David Hall

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cylinder in different ucs
« on: November 17, 2006, 02:52:08 PM »
OK, i have stumped myself again.  Im trying to define a new ucs and draw a cylinder in that ucs, not the wcs.  here is my code so far
Code: [Select]
Public Sub ucstest()
    Dim ucsObj As AcadUCS
    Dim origin As Variant
    Dim xAxisPnt(0 To 2) As Double
    Dim yAxisPnt(0 To 2) As Double
    Dim ucsorigion(0 To 2) As Double
    ' Define the UCS
    origin = Null
    origin = ThisDrawing.Utility.GetPoint

    xAxisPnt(0) = origin(0): xAxisPnt(1) = origin(1): xAxisPnt(2) = origin(2) - 1
    yAxisPnt(0) = origin(0): yAxisPnt(1) = origin(1) + 1: yAxisPnt(2) = origin(2)

    ' Add the UCS to the UserCoordinatesSystems collection
    Set ucsObj = ThisDrawing.UserCoordinateSystems.Add(origin, xAxisPnt, yAxisPnt, "New_UCS")
    ThisDrawing.ActiveUCS = ucsObj
    ThisDrawing.ModelSpace.AddCylinder origin, 1, 3

End Sub

I think I need to transform my coords somehow, but I have never done that, so any ideas what I should do?
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David Hall

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Re: cylinder in different ucs
« Reply #1 on: November 17, 2006, 02:53:20 PM »
the cylinder uses this
Quote
RetVal = object.AddCylinder(Center, Radius, Height)

Object
ModelSpace Collection, PaperSpace Collection, Block
The object or objects this method applies to.

Center
Variant (three-element array of doubles); input-only
A 3D WCS coordinates specifying the center of the bounding box.

Radius
Double; input-only
The cylinder radius. Must be a positive number.

Height
Double; input-only
The cylinder height. Must be a positive number.

RetVal

3DSolid object
A 3DSolid object as the newly created cylinder.
the variant is in WCS, and i think that is my problem
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David Hall

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Re: cylinder in different ucs
« Reply #2 on: November 17, 2006, 02:55:46 PM »
Or for those that want the big picture, what I really need to do is
Quote
1-draw a circle
2-rotate3d the circle to horizontal or vertical based on extrude direction
3-extrude circle along a path
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Bryco

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Re: cylinder in different ucs
« Reply #3 on: November 17, 2006, 03:51:47 PM »
When you insert the circle it is inserted in world coordinates but it will assume the normal of the currnt ucs. Set the circle.normal to 0,0,1 then transform the circle using your ucsmatrix

CADaver

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Re: cylinder in different ucs
« Reply #4 on: November 17, 2006, 04:23:21 PM »
If you just wanna draw a circle and extrude, carry on...

... but

There is the cylinder command that asks for the first end center and radius, then prompts for "height of cylinder or [Center of other end]" and it allows you to place the center of the other end anywhere in space regardless of UCS.  Might be worth an investigation.

David Hall

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Re: cylinder in different ucs
« Reply #5 on: November 17, 2006, 04:34:56 PM »
its really dirty, but my brain is shutting down.

This works, but there are a few quirks:
1-you pick a line that defines where the cylinder goes
2-you pick the midpoint of the line b/c the cylinder gets placed by the centroid
3-you have to pick a third point perp to the line (ortho/polar on is a good thing)


Code: [Select]
Public Sub ucstest()

    Dim origin As Variant
    Dim xAxisPnt As Variant
    Dim yAxisPnt(0 To 2) As Double
    Dim ucsorigion(0 To 2) As Double
    Dim objcyl As Acad3DSolid
    Dim dblLength As Double
    Dim objLine As AcadLine
    Dim varpick As Variant
    Dim obje As AcadEntity
    ThisDrawing.Utility.GetEntity obje, varpick
    Set objLine = obje
    dblLength = objLine.Length
    origin = Null
    origin = ThisDrawing.Utility.GetPoint
    xAxisPnt = ThisDrawing.Utility.GetPoint(origin)

    Set objcyl = ThisDrawing.ModelSpace.AddCylinder(origin, 1, dblLength)
    Dim ang As Double
    ang = 90
    ang = ang * 3.141592 / 180#
    objcyl.Rotate3D origin, xAxisPnt, ang

End Sub

More cleanup required on Monday
« Last Edit: November 17, 2006, 04:39:34 PM by CmdrDuh »
Everyone has a photographic memory, Some just don't have film.
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Bryco

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Re: cylinder in different ucs
« Reply #6 on: November 18, 2006, 05:50:27 PM »
Here's a couple of examples.
The first 2 work with the normal and the third uses a ucs
Code: [Select]
Public Sub CylinderFromLine()

    Dim oCyl As Acad3DSolid
    Dim oCircle As AcadCircle
    Dim oLine As AcadLine
    Dim varpick As Variant
    Dim Ent As AcadEntity
    Dim N, oReg
    Dim RegEnt(0) As AcadEntity
    Dim V(2) As Double
    Dim Unit As Double
    Dim Vn(2) As Double
    Dim P1, P2
   
    ThisDrawing.Utility.GetEntity Ent, varpick
    If Not TypeOf Ent Is AcadLine Then Exit Sub
    Set oLine = Ent
   ' V = oLine.Delta 'Don't use the treacherous delta
    P1 = oLine.StartPoint: P2 = oLine.EndPoint
    V(0) = P2(0) - P1(0): V(1) = P2(1) - P1(1): V(2) = P2(2) - P1(2)
   
    'Normalise the vector(It's length=1)
    Unit = Sqr(V(0) * V(0) + V(1) * V(1) + V(2) * V(2))
    Vn(0) = V(0) / Unit: Vn(1) = V(1) / Unit: Vn(2) = V(2) / Unit
   
    Set oCircle = ThisDrawing.ModelSpace.AddCircle(oLine.StartPoint, 1)
    oCircle.Normal = Vn
    Set RegEnt(0) = oCircle
    oReg = ThisDrawing.ModelSpace.AddRegion(RegEnt)
    Set oCyl = ThisDrawing.ModelSpace.AddExtrudedSolid(oReg(0), oLine.Length, 0)

End Sub

Public Sub CylinderFromPoints()
    'this mimics the Cylinder command
    Dim oCyl As Acad3DSolid
    Dim oCircle As AcadCircle
    Dim Rad As Double
    Dim P1, P2
    Dim N, oReg
    Dim dLength As Double
    Dim RegEnt(0) As AcadEntity
    Dim Util As AcadUtility
   
    Set Util = ThisDrawing.Utility
    P1 = Util.GetPoint(, "Specify center point for base of cylinder:")
    Rad = Util.GetDistance(ToUcs(P1), "Specify radius for base of cylinder:")
    P2 = ThisDrawing.Utility.GetPoint(ToUcs(P1), "Specify center of other end of cylinder:")
    Dim V(2) As Double
    V(0) = P2(0) - P1(0): V(1) = P2(1) - P1(1): V(2) = P2(2) - P1(2)
    Dim Unit As Double
    Dim Vn(2) As Double
    'Normalise the vector(It's length=1)
    Unit = Sqr(V(0) * V(0) + V(1) * V(1) + V(2) * V(2))
    Vn(0) = V(0) / Unit: Vn(1) = V(1) / Unit: Vn(2) = V(2) / Unit
   
    dLength = Sqr(V(0) ^ 2 + V(1) ^ 2 + V(2) ^ 2)
    Set oCircle = ThisDrawing.ModelSpace.AddCircle(P1, Rad)
    oCircle.Normal = Vn
    Set RegEnt(0) = oCircle
    oReg = ThisDrawing.ModelSpace.AddRegion(RegEnt)
    Set oCyl = ThisDrawing.ModelSpace.AddExtrudedSolid(oReg(0), dLength, 0)

End Sub

Public Sub CylinderFromUcs()
    Dim oUcs As AcadUCS
    Dim Orig As Variant
    Dim xAxisPnt(0 To 2) As Double
    Dim yAxisPnt(0 To 2) As Double
    Dim oCyl As Acad3DSolid
   
    Orig = ThisDrawing.Utility.GetPoint
    Set oCyl = ThisDrawing.ModelSpace.AddCylinder(Zero, 1, 3)
    ' Define the UCS
    xAxisPnt(0) = 0: xAxisPnt(1) = 0: xAxisPnt(2) = -1
    yAxisPnt(0) = 0: yAxisPnt(1) = 1: yAxisPnt(2) = 0
    Set oUcs = ThisDrawing.UserCoordinateSystems.Add(Zero, xAxisPnt, yAxisPnt, "New_UCS")
    oUcs.origin = Orig
    oCyl.TransformBy oUcs.GetUCSMatrix

End Sub


Function ToUcs(pt As Variant) As Variant
    ToUcs = ThisDrawing.Utility.TranslateCoordinates(pt, acWorld, acUCS, False)
End Function
   

David Hall

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Re: cylinder in different ucs
« Reply #7 on: November 20, 2006, 12:32:54 PM »
Bryco, those work perfectly.  :-D :-) :-D

 Now, can you explain what is happening so I know what is happening so I can use that in the future?  Great job.
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Bryco

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Re: cylinder in different ucs
« Reply #8 on: November 20, 2006, 12:59:26 PM »
Thanks CmdrDuh. I was going to try an article on this stuff but it's going to take a little while.
Beware of the Ucs method for objects other than cylinders, for some reason a cylinder works a little different than other entities.
Help says "Creates a 3D solid cylinder whose base is on the XY plane of the WCS." Usually you insert something in world, make sure the normal is 0,0,1, then transform it to the ucs (or matrix) you want.

Fatty

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Re: cylinder in different ucs
« Reply #9 on: November 20, 2006, 03:36:13 PM »
Bryco, I enjoyed with your code again
Thanks for elegance
(Ya da ..)

:)

Fatty

>'J'<

David Hall

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Re: cylinder in different ucs
« Reply #10 on: November 20, 2006, 03:46:31 PM »
Couple of things, on the last example, it bombs on using "Zero' as undefined.  Probably a snippet from somewhere else.

on to better things:
I think I have figured out part of the math.  The P2-P1 part is calculating the delta X, delta Y and Z right?  I drew some lines using known XYZ coordinates, and that's what looks like is happening.
now here is where I am not entirely sure whats going on
Code: [Select]
    'Normalise the vector(It's length=1)
    Unit = Sqr(V(0) * V(0) + V(1) * V(1) + V(2) * V(2))
    Vn(0) = V(0) / Unit: Vn(1) = V(1) / Unit: Vn(2) = V(2) / Unit

After talking with the resident math guru here at work, my question is wouldn't the oCircle.Normal work with V or Vn?  I tried it, and it  does in fact work.  So,  my final question is why did you have to normalize the vector?
Everyone has a photographic memory, Some just don't have film.
They say money can't buy happiness, but it can buy Bacon and that's a close second

Bryco

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Re: cylinder in different ucs
« Reply #11 on: November 20, 2006, 05:20:58 PM »
CmdrDuh, Zero is a property that I use that I am very proud of (Some people are easy)
Property Get Zero() As Variant
    Dim Z2(2) As Double
    Zero = Z2
End Property
this is public so I never have to write
dim insPt(2) as double
Now all my insertion points are just Zero.

Normals, normals are rather finicky so I guess I just normalise them as habit.
When you use the normal in making a transformation matrix you need to normalise it as well.
But you are right no need to do unnecessary math.

Fatty, thanks mate.