UDT Commands in Rhino

UDT Commands in Rhino

UDT stands for Universal Deformation Technology. The UDT tools allow you to deform meshes, lines surfaces, polysurfaces and solids without worrying about the integrity of the object. You can access some of the UDT commands under the transform menu, or by right-clicking in an empty area next to a toolbar and selecting the default.UDT toolbar

The commands include the following

Maelstrom Splop Stretch

Cage Edit

Twist

Bend

Flow Along Surface

Taper Flow Along Curve

Stretch As the name implies, the stretch command allows you to stretch an object. After selecting the object you want to stretch, you specify the stretch axis start and end points. These points dont have to be on the object itself, but deciding where the axis starts and stops can have a dramatic influence on the result, as whatever falls between these two points will be affected. For instance, choosing two points at the extremes of the object means that the entire object will change

If we dont want the spheres at the ends to shrink, we must start and stop our stretch axis short of them

End of axis Start of axis The ability to decide where you want the stretch to occur gives this tool advantages over the more basic 2-D Scale command. Of course, there are many additional options for this command (see help file for more info). Bend In some cases, its easier to create a shape as a flat object, and then apply one of these transformations to it after wards. For these situations, we have the bend command. The bend command allows you to bend an object along a spine which you define. Starting this command, we select our object, and then specify the start and end of the spine

Start of spine End of spine

Like the stretch command, the position of our spine determines where the bend occurs on our object. To have the bend occur for only part of the object, we specify that area when we define our spine

When the spine falls somewhere in the middle of the object, using the Symmetric option ensures that the bend occurs symmetrically on both sides of the spine

Original Spine

Without Symmetric option With Symmetric option

he faucet below is a great example of a situation where this command is used properly. We have added all the detail to our faucet (i.e. applied fillets, booleaned verything together so it is a solid) all that is left to do is apply our bend to the neck

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I have drawn a line (red in the image) that passes through the center of the faucet and which will serve as a guide for snapping to once we start the bend command.

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We start the bend command. We select the faucet as the object to bend. For the start of the spine, we snap to the bottom of the red line, and for the end of spine, we snap to the top of the line. Turning on only your end snap makes it easy to make these selections. You can select the line from which ever viewport gives you the best view (front view

ed best for me).

Having defined the spine, you are now in bendtill you like what you see. If you arent getting e result your options set as follows ( Copy=No Rigid=No LimitToSpine=Yes Angle Symmetric=No ): When you left click, the command will end.

Start of Spine End of Spine

mode. Go into the right viewport and drag th you expect, make sure you have

Start the command, select the object, then dr

Taper The taper command allows you to taper an object.

aw the start and end for the taper axis.

By default the command will create a curved taper

To create a flat tapper, to

ggle the Infinite option to Yes

As with other commands, where we start and stop our taper axis will determine where the ansformation occurs

There is one drawback to using these commands. They add many control points to the resulting surfaces. These added points slow th oftware down, especially when multiple objects are involved. Deciding when and how to use these commands must be decided on a case by case basis. Ideally, you want to use them in moderation - to fine tune a design after most of the modeling is complete. Cage Edit Cage edit works by creating a cage that con rols the objects shape. The control points of the cage essentially become the control po ts of the object. Having a regular spacing of points in a predictable shape is very useful as it allows for smoother transitions

n (or go to Transform > Cage Editing > Cage dit). It asks us to select our Captive Objects (the object we want to edit), so we select e object in the viewport. Next, it asks us to select how we will control this object. This

cage that perfectly fits the object. For the Coordinate System, use the CPlane ption. At the Cage points option, you specify how many control points you want in each

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between areas of an object than could be achieved with normal surface-based control points. Also, you can edit polysurfaces without worrying about separate surfaces becoming un-joined. To start, left-click on the Cage Edit buttoEthwill create aodirection, and the degree of influence each point will have on the surrounding surface (lower numbers will create sharper transitions; a setting of 3 is default)). Accept the defaults for now and click Enter.

You should now see a box (the cage you just created) surrounding your object While still in the c ult for the region to edit and hit enter.

ou should now see control points on the cage you created.

ommand, accept the Global defa

Y

We can now modify the shape by selecting specific points and dragging them

t any time, you can hit ESC to hide the points and F10 to make them visible again.

ith a few more clicks we get the following

A W

Before and after cage editing

When you are done editing the cage and want to remove it, hit esc to exit out of control

oint mode, then select the cage and delete it.

There are many options and variations on the cage command. We will cover a few more here. For this example, we will again run the Cage command, but this time lets use the Line option as our control object After drawing the line, the prompt will allow us to define the degree of the line and the PointCount (just like we did for the BoundingBox in the example above). Again, this will establish how many points of control we will have and how extensive the influence of each point will be on the caged object. Accept the default settings and hit enter. Accept the Global setting for region to edit, and after clicking enter, you should see the line you created with its control points visible.

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Moving control points away from or towards each other parallel to the line will stretch the object. Any other change in position of the control points will result in a curved distortion Curving in two directions

Had we increased the number of control points of our control line, we would have a finer degree of control over how and where distortion takes place.

One final example using the Cage Edit command involves editing only a small area of an

Start the Cage Edit command, use the Line option for your control object, and draw the line on the object itself

object.

rag one of the control points. The preview looks sort of odd, but when you release, the eformation occurs as we would expect, relative to our control line

Dd

This is similar to the bend command we looked at earlier, but we can bend the object in all three axis.

Run the Cage Edit command but, this time, choose the Rectangle command after

rawing a rectangle around your selection, you now have a rectangular cage with which control your object

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he rectangular cage is somewhere between the full 3d cage and the line in terms of

aelstrom This command deforms an object in a spiral motion. Start the command, and select the object you want to deform

Tcontrol and complexity. M

Next, we specify the center of the distortion. Then we specify the two radii. The space between these two circles is the area we want to have affected by the maelstrom.

First Radius

Second Radius

We can then set the amount of distortion by dragging the mouse and viewing a preview

he shape a

T fter the maelstrom command

Twist You can use the twist command to twist an object. For this example, we will use the following extruded profile

After starting the command and selecting our object, we define a twist axis. This doesnt

iews (front in this case). Also, if you want your bend to be in multiples of 90 degrees, nd you are dragging rather than inputting a numeric angle, I suggest you turn on Ortho aps or hold down the shift key BEFORE you left click to start your first reference point r rotation.

did 3 full revolutions (1080 degrees) and then ended the command

have to be parallel to the piece it doesnt even have to BE on the piece, but we will use an edge of the piece to keep things simple for this example.

Start

End

We can now interactively bend the shape. I found it easiest to do this in one of the plan vasnfo I

here we place our twist axis will determine how the object is twisted. Placing this axis ght through the center of the object (as opposed to on the edge as in the example above) roduces a twist that is symmetrical with the object...

etermines over what distance the twist takes place. If you want the bject to twist constantly throughout, toggle the infinite to yes. With the option set to no, the twist will blend in and out at the ends

W

Front view during preview

Twist Axis

Twist Axis

rip

The infinite option do

Using the infinite yes option will apply the twist to the entire object, even if the axis is shorter than the object. Like the other commands, the twist can be applied to select areas of an object. The twist will start and stop where our twist axis starts and stops, provided we set the infinite to no

Infinite set to no

Twist blends at the ends

Infinite set to yes

Twist extends to the ends

Twist axis end

Twist axis start

plop The Splop command allows you to copy, rotate For this example, we will use an organic suwith more points).

S

, scale and wrap an object to a surface.

rface (create a plane and rebuild it rebuild it

Start the command and select the star shape as the object to Splop. We need to create a here that will become a reference when we lace copies of the object on our surface. For is shape, I used the 3Point option.

hen we are done clicking, we see a preview of a wireframe sphere. We now select the rface we want to splop onwe left click to start the center of our object, then move the ouse away from this point to determine the scale, left click again and a copy is

spth

Wsumcreated

After Sploping a few more stars

gle the flip option to yes if it appears upside down on the surface. lso, by default, the object will deform in order to remain perpendicular to the surface. ou can toggle this to rigid, so it doesnt deform

You may need to togAY

Rigid = Yes

Rigid = No

Rotation of the object is specified after you pick the Splop drop point by simply movingaround the drop point

he center of rotation is the same as the center of the reference sphere you create.

T The equator of the reference sphere determines how far down the object sits on the surface. Everything from the equator of the sphere and above will show above the surface

Splop works with curves as well

hese curves reside exactly on the surface, so using the trim command we can edit the rface with the curves

inally, Splop also accepts surfaces as input

Tsu

or

F

think about volume, surface and line, and ow you go about designing an object. Using the Splop command can greatly simplify

g Curve allows you to re-align an object or group of objects to a curve.

The Splop command can really alter how you hhow you create complex geometry. Flow Along Curve Flow Alon For this example, lets start with a circle and an extruded shape

Start the Flow Along Curve command. Select the extrusion as the object to flow along the urve. The next prompt asks for a base curve. Select the Line option. Turn on your End ap and snap to the top two corners of the extrusion

tch option is set to yes. s to complete the curve. Now click on the circle. If all went well, curve

csn

Start of line

Make sure your Stre

End of line

This will ensure that our extrusion stretche

a copy of your extrusion now flows along the

Our first and second picks for the line determine whether the extrusion sits inside or utside of the curve

o

2nd pic

1st pick

k

1st pick

he circles are stretched because we ha

we dont want the circles on our extrue stretch set to no

2nd pick

T Ifth d the stretch option set to yes.

sion to stretch, we can re-run this command with

Without stretching, our extrusion is too short to completely follow the curve.

o what if we want to not dis s? We need to make the extrusion the same ngth as the curve. We can find out how long the curve is by Going to Analyze > Length

nd selecting the circle as the curve to measure. In the command prompt, Rhino tells me:

t, to copy this value, then create a new extrusion by pasting this value with CTRL-

), and re-run the Flow command without the stretch option, the extrusion now ompletely follows the curve

S tort the circlelea If I make my extrusion using this length (i.e. highlight the value in the command prompCTRL-C Vc

the area where one end of the extrusion m spacing when I remade the extrusion and there was some material left over.

The hole spacing is regular until you come toeets the other. This is because is kept the same

Larger gap

Smaller gap

Larger gap

Smaller gap

If we really wanted to make spacing regular, we would need to change the spacing of the oles to ma

he Between Snap

ne more detail to consider. When specifying your base curve, if the spot you want is not snappable, like the center of a face for instance, you can use the Between snap to ecify a location that is between two snappable points.

ets demonstrate this by dropping a point on the center of a face. Start the Point ommand. For location of Point, notice that there is no direct way to snap to the middle f the end face of our extrusion. Now turn on the mid snap, then hover over the snap olbar area and hit the CTRL button

h tch the length of the extrusion. T Osp Lcoto

Regular Snaps

Bonus Snaps when CRTL key is pressed

Between here (first click) And here (second click)

A point is created between the clicks above The between snap works anytime you are asked for a location. Also, it lasts only for one

put, so if you are defining an axis, you will need to run it twice. in