Lofting Shape Copies--Bug in v5.1?

Lofting Shape Copies--Bug in v5.1?

Post by mm » Thu, 03 Jul 2003 03:04:22



I attempted to make a loft object using a series of shapes.  I first
made a shape then copied and scaled the shape to produce the series of
individual shapes (using copy, not instance or reference).  Then I
created a path and attempted the loft.  The problem is, no matter
which shape I selected, only the original shape is used.

Is this a bug in 5.1 or am I missing something.

--Mike

 
 
 

Lofting Shape Copies--Bug in v5.1?

Post by Conny Klasso » Thu, 03 Jul 2003 04:16:57


Yes you're missing something.
Scale doesn't change the object, it just makes it appear at another size.
Just like Move, it just makes it appear at another place.

And the transformations (Move, Rotate &Scale) are performed last
in the "graphic pipline". You need to inwoke the scaling into the
object's modifier stack so the scaling takes effect before the lofting.

Reset the Scale transformation.
Apply XForm (Transform) modifier.
While Xform is selected in the modifier stack,
redo the scaling, now it should work in the loft object.
Or use the "Reset XForm" utility to convert the
transformation into a XForm modifier.

Never use the Scale transform to "modify" objects.
Unless:
A. You operate at mesh sublevel. Scaling selected vertices is safe.
B. Use the XForm modifier to hold the scaling in the stack.

To really prove my point, follow this short tutorial:
1. Create two equal cylinders.
2. Increase the height of first cylinder. Make it twice as high.
3. Non-Uniform-Scale the second cylinder to the same height.
4. Apply the Bend modifier to both cylinders, set the bend angle
to something predictable like 180 degrees.

Notice how the scaling of the second cylinder takes effect AFTER the
bending.

Conny



Quote:> I attempted to make a loft object using a series of shapes.  I first
> made a shape then copied and scaled the shape to produce the series of
> individual shapes (using copy, not instance or reference).  Then I
> created a path and attempted the loft.  The problem is, no matter
> which shape I selected, only the original shape is used.

> Is this a bug in 5.1 or am I missing something.

> --Mike


 
 
 

1. Lofting two shapes into one shapes without severe twisting

    I'm in a situation where I am trying to loft a two pronged fork
using the appropriate series of shapes. This requires, at the end, two
points (circles), a base of divergence, and a handle. I understand that
lofts can extrude along a path with any number of shapes, provided that
each shape contains the same number of splines. In order for the handle
splines, etc. to be compatible with the points i have broken them into
two(splines)  while retaining their shape. The problem lies in the
really ugly twisting that occurs when base forms into the two prongs.
One side seems to form correctly, but has a few faces stretching out to
form into the other pronged side.

    I know one inherent problem is that you have a cylinder shape
forming into two points. Something needs to happen to the middle of
cylinder.... but any shape going from enclosed to two separate shape
produces a twisting.

    There's a pic of this prong fork in Inside 3d Studio Max 2 Vol 1 at
pp353 (fig. 9.8). The same book discusses how this techniques works on
page 363. And it works (abstractly), but the severe twisting makes it
unusable. I'm pretty annoyed that they didn't cover this technique with
a brief tutorial and was hoping for some help. :)

sincerely,
Hel?Atropos

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