Feeling tied up with your current modeler?
Here's how to tie the knot with Amapi :-)
by  Philip Staiger
New! Click here to skip to the bottom and see some samples of rendered images with knots.
Here's a quick tutorial for creating a knot. Select the Draw tool from the construction toolkit



Then select the Interpolated curve.



Start drawing a link from the left side, just a very few clicks.

As you can see, Amapi generates an interpolated curve, going through the clicked point locations.

Start drawing that knkot shape.
Be sure to use the arrow keys to progressively change your view.

Now looking at it from the side (from behing the starting point of the curve).
Make the curve go under itself.



And make the curve continue turn around itself and up over it, heading
for the loop opening.



this shot is from above,

There, that will do for starters.

Use the Stretch tool to move the control points a little bit in order to make
a better knot shape.

Don't spend too much time on this yet, we'll be able to further fine tune the shape soon.


Let's create a circle now, as the cross section of the rope.
Be sure to select Nurbs mode, if you want an additional level of control
and compression in memory size for use in ZAP files.



Draw a circle somewhere out there.
Make it approximately the size you'll want for the rope's thickness.



Now on to the Sweep tool.
First, click the circle to make sure it's
the current object.

   Then click the Sweep tool in the construction toolkit. 

Then click the knot's path curve (interpolated curve).

Hit the SPACEBAR to select the desired orientation of the circle against the path
(perpendicular to the curve). Use the arrow keys or the navigation trackball
at the bottom of the screen (control panel) to inspect the result.

When done, hit ENTER to generate a shaded rendering.


If there's an area which you don't like or looks too squeezed, it's easy to use the stretch tool again.

Amapi's dynamic geometry feature shows that you can choose to edit various levels of primitives, such as the meny vertices of the mesh created by sweeping, or the Nurbs control cage, or the interpolated curve and circle (construction curves of the Nurbs surface), or even the originally clicked control points of the interpolated curve (which is a Nurbs curve too). That one is actualkly the default, so it's very easy to edit a single vertex on the interpolated curve and get the whole resulting swept curve to be regenerated anew - automatically.

If your PC or Mac is too slow to handle this dynamic update, click the eye icon (top left) to disable immediate feedback. The update then happens only when you release the mouse after dragging a point.

It may help to have a floating view (View > New View > Free View )


After a few layers of texturing applied with Amapi's shader,
and a few spot lights casting shadows:

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Gallery of Images, modeled and renderd in Amapi 5.1
 

Click this icon for large view: click me
 

"Waiter, there's a knot in my glass!?!"

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