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Bitmapping a lathed cylinder
This
tutorial describes the process of wrapping a bitmap
material around the outside of a cylindrical lathed
object. This, much like extrusions, tends to give some
Swifters a lot of grief trying to line the image up
correctly.
The most common use for this would be to bring realism
and life to such things as bottles, cans and basically
any tubing/cylindrical shape that requires a full graphic
coating.
For this tutorial we will concentrate on the soft drink
can.
So how do we do it? |
Step
1 - Creating the object
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Creating
the object is very simple. To create the cylinder we
only need to draw a profile of half of the can in the
lathe editor.
Work
in either the top or bottom quadrant as this will affect
the material location when we apply the bitmap material
later on.
The
sweep angle is set at 360º, smoothing is on and
if you want a high end finish, set the segments to 64.
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By
jumping between the lathe and main editors you can refine
your bezier points of the lathe until you are satisfied
you have a well proportioned object. |
Step
2 - The
bitmap
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When
using a bitmap it is important to note that the program
squares up your image.
e.g. - A 200x100px image will become 200x200px. That
isn't the actual size it becomes, I am merely trying
to convey that the image becomes a square shape. I have
supplied the bitmap I used so you can continue the tutorial
without scouring the web for a decent image.
The
image on the left is 512x502 px in size and can be downloaded
here.
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Step
3 - Creating the
material
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Go
to - Setup > Materials.
Highlight "Bitmap"
from the list and select "Add Material...".
Give your new bitmap texture a Name (e.g. 'diet coke'
). In the Finish sub-panel, open
the Ambient Color picker - select
white. In the Color sub-panel, select
"Bitmap Image" from the Pattern
drop down menu. When prompted to select a
file - select the diet_coke_material.bmp file. Select
"Cylinder" from the Wrap
drop down menu. Check the Scale box.
Leave all other settings at their default values!
Hit
"OK" and "Done"
respectively. You can view the full panel image with
all settings required .
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Step
4 - Applying and aligning the material
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To
understand the way bitmaps are wrapped around the
surface of a lathe, I have put together a demonstration
as shown on the left, of where the bitmaps are positioned
within the lathe editor. As you can see - each quadrant
has it's own image and it always starts at absolute
centre. That's 0,0 position co-ordinates.
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From these positions the program starts to wrap around
the lathe object. I have created 4 lathed objects with
sweep angles of 180º, 270º, 320º and
360º. See how each time they start from the centre
and wrap out along the lathe. Now the most important
thing to remember in this tutorial and what you are
looking at in the left image is this: The manual says
the default setting for the scale of the bitmap material
is 1:1. This is not quite correct. It is off a bit.
By selecting the Scale radio box when
creating your material it scales it to 1:1. Do not adjust
the slider. This is where all the problems stem from
when trying to wrap. So now it will make the bitmap
start at the beginning of the sweep and end at exactly
360º. A perfect fit. |
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As proof, the two lathed objects on the left are identical.
I then created and placed a material on the left one
which has the Scale radio box selected.
The other one has a copy of the same bitmap material
but with the Scale radio box deselected.
Does the latter image looks familiar when you tried
to wrap?
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To
continue, you simply apply (drag and drop) your newly
created bitmap material to the lathed object and it
will fit. If the image carries on past the bottom or
top of the object - go back to the lathe editor and grab
the bottom/top of the lathed object and drag it up or
down to bring it back in line with the bitmap material
now that you know where it is sitting in the lathe editor
window. Use the height scale to bring the object back into proportion if needed. |
Step
5 - Completing the scene
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For
my demonstration I moved the lights around and darkened
them slightly to reduce the glare coming off the objects.
The whiteboard marker was created in the exact same
way the can was. The table is just a round cornered
extrusion with a wood grain material applied. The
background is another extrusion with an image of some
chairs on it.
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