Basic Splinemanship II (Revised 2/11/00)

More Working With Hash Splines

©1999 By Jeff Cantin aka TinCan on IRC

In this section of Basic Splinemanship, we will explore more of the tools, how to create primitives on the fly, and then combine them to make simple models. Let's all set AM's properties to match what I'm using: Launch AM, open the Tools, Options, Units Tab and set the Units to Centimeters and the Paste/Extrude X Y offsets to zero. In the Modeling Tab, type in 8 cross sections (the default) if it has been changed. (I also changed the size of the CP display just to clarify the screen shots.)

Reason: we want copy/pasted mesh to be exactly where the original was. (you'll see later)

Caveat: Pasting exactly over the original can cause double geometry if you're not careful -- it is hard to see any tell-tail signs when this occurs.

All righty then, let's begin... Open a new model window and expand it to fill the workspace. We're going to use the add mode, add-lock, extrude, copy/paste and snap-manipulator buttons a lot, as well as these short-cut keys:
<o> Smooth
<p> Peak
<,> Complement Spline (comma key)
<.> Complement All (period key)
</> Group Connected (slash key)

If you aren't sure what these do, now is a good time to drop back to the first section of Basic Splinemanship, if you decided to continue -- they should start to make sense with use.

Draw a spline using the add mode from approximately 15, 5 to 15, -5 hi-lite the whole thing, right click and select snap to grid. Since we already have the lathe tool set to 8 sections, click on one CP and whack the lathe button. Now we have an open ended tube. Change to birds-eye view and we will elegantly close the top and bottom. I say elegant because we will use a method that keeps the patch count small and still not create internal patches (for more info on internal patches, read my tut on the subject Internal Patches).

Select any CP on the bottom spline, hit the <,>key to easily select the whole bottom spline, then extrude and resize the new spline ring smaller via the yellow handles of the selection and whack the delete key. Now we should have spline tails to work with. Select any two adjacent "tails" and delete them. Join the pair next to those and delete that CP, do the same to the next pair, and then delete the final two tails. You should have three 4-point patches closing the bottom.

Now do the same thing on the top spline ring, only choose a different location to delete the first set of tails. See? Fully closed and no internal patches! I call this closure elegant! :-) Ok, so it looks funny, because the side to top splines are smooth and need to be peaked. Hi-lite the whole thing and hit <p> then select the bottom spline ring and with the <,>key select it all and hit <o>. Do the same for the top spline ring. Render to see our new hockey puck! LOL

Because this is a tools tutorial, we did it this way to demonstrate a lot of tool use, i.e., <,> <o> & <p> keys. We could have closed it off with add mode splines as well -- and still have had to peak & smooth. Or, we could have used the add-lock mode and drawn (4) four CP splines, connecting the inside two CPs to the bottom and top spline rings and skipped extruding, peaking and smoothing. I want you to try those methods now, before going any further. The resulting mesh will look the same, render the same, have the same number of valid 4-point patches, but the last method will have a different arrangement and number of splines, not that it matters for our purposes.

Note: multiples of 4 in the cross-sections all close nicely, give it a try with the lathe tool set to 12 or 16 and remember to close the top slightly different than the bottom -- avoiding internal patches.

Now let's play with the Scale Tool!
Let's save now and while still in the birds-eye view, select all <ctrl A> and copy (don't paste) then click on the scale mode manipulator button or press the <s>key. Man! We got all kinds of colored handles and doohickies on the screen! Don't get overwhelmed, if you look at the color coded handles and peek at the bottom left corner of the screen you'll see what each handle does. Move your cursor over all the hot spots, including the common yellow ones. Now grab any non-yellow handle that says "scale" in the status bar and slide it around. Do the same with the dual-colored handles (like the red/blue scale in X Z). Be brave and really move them about, if you have the normals turned on, you should notice they flip once you drag a handle clear across to the other side! Don't worry about bringing it back to our puck shape, when you're ready to continue hit the delete key and press paste. :-)

Turn on the scale mode again, this time when you grab the red/blue handle, hold down the shift key while dragging. You should see the circle retains it's shape and does not turn into an oval, or to say it another way, the aspect ratio is constrained. Again, try the other multi-colored handles & shift until you are familiar with how the scale manipulator works. When finished, delete and paste.

Well, now I hope you can see our puck could be a pole, a thin coin, or an oval thingy! Same model, same mesh -- just scaled differently. We will use this a lot in our quickie model making, that is, copy a section of mesh and change it's scale to fit our needs.

By selecting just the top spline ring and scaling, it beveled the sides. I slapped a Darktree texture on it and have a kewl plaque style stand. So, don't think ya have to always scale the whole mesh -- test out the scale tool on your own stuff or protions of models from the A:M CD. Using this tool could make a long face into a more rounded one.

Next, we play with the Rotate Tool!
The Rotate Tool has the same multi-colored handles, but has more stuff -- hidden. Select all, then click on the rotate button or press the<r>key. We have just entered the rotate mode, notice on the rings of the rotator are the color coded handles, they match the axis but also notice the status bar lower left and the how the cursor icons change when you move the mouse over the hot spots. If you grab a colored handle you can only rotate on that axis, try it yourself. Remember, you can always delete and paste to get back to our "default puck shape." Next, grab anywhere on the rotate sphere when the status bar says "free rotate." This is like a virtual trackball and you can rotate in any direction.

Did you notice when you grabbed it by the handles the rotator kinda snapped in small degrees, but when you free rotated everything moved smoothly? When using the colored handles the rotator snaps to the number of degrees set in the Tools, Options, Units Tab where the default is 5 (degrees). Change it to 45 for a few minutes and go back and rotate via the colored handles again, you may have to move your mouse farther to get it to snap. Get the idea? Suppose you wanted to rotate your mesh exactly 12.5 degrees in any direction, simple! Just type 12.5 into the Units Tab! Ok, another tip... if you had the properties panel opened you can watch in real time the values change as you rotate the mesh. So, if you had set the units to 12.5 but this one time you wanted to rotate 18 degrees, just type it directly into the appropriate box in the prop panel and hit <Enter>.

OK! Take a break (look at some pretty images on my homepage ;-) and when you're ready we will learn some kewl copy/paste flip on the axis tricks.

Kewl copy/paste flip on the axis tricks...
Now that you can take our shape and scale it at will, let's do something with it. Select it all, rotate it so it's pointing to the front, er, red handle 90 degrees :-) Change to the scale manipulator and scale it in the Z axis and then scale in the X-Y with the shift key. We don't care exactly how much, but make it longer and thinner. Kinda like this.

Change to the front view <Keypad 2> and click on the "Snap Manipulator to Grid" button. Press the up arrow cursor key twice, and the left arrow cursor key thrice... Whack copy, whack paste, and while the mesh is still hi-lited, tap the right arrow cursor key 6 times. Notice how the whole thing moves in grid units, grab that portion and move it with the mouse -- same thing, it snaps to the grid, ok reposition it 6 units to the right of the first one. Kewl! Paste again, and while it is still hi-lited, rotate it up and down, red handle 90 degrees. De-select, group select the very top of that piece, and cursor it down to the center of our "pod." Now, select the bottom and cursor it up towards the pod, stop about 3 grid units away.

Whack the </> key to select the whole group and <s> for the scale mode and scale it long and narrow, kinda like this:

Change to the rotate mode <r> and from the from view <keypad 2> grab the very center handle of the rotator's icon thingy (look at the status bar lower left and it should say "translate pivot") and move the pivot's position to match the top of the hi-lited mesh. The rotator icon will re-draw in the new location sometimes expanding off the view screen, if this happens just use the zoom tool and zoom out a tad. You can do this without de-selecting the mesh. Grabbing the blue handle on the ring, rotate the mesh towards the green axis line, I did mine to -40 degrees, but you can do -35 to -45. Notice how moving the pivot point helped swing this piece into position! It will come in very handy in your quicky modeling.

Note: Whenever you group select the software will try to put the pivot point to the center of the mesh, if you move the pivot and de-select, the pivot's new location is gone. But wait! There's more... When you group select you can make a named group, now if you move the pivot the new location of the pivot will be retained in that named group. So while that mesh is still hi-lited, name the group, be creative. Now, let's test this; de-select, then group select the same mesh, the pivot is back at the center, ok click on the group's name on the PWS -- Yuppers, the pivot is right where we moved it to (pivot is easier to see in rotate mode)!

Back to our modeling, display the prop panel, select our named group and in the pivot tab type in "0" (Zero) for the X axis, press copy, then right click on the hi-lited mesh and choose flip (not copy/flip/attach) and on the smaller menu flyout click on X Axis, then whack paste... Way kewl, now you can see why we wanted to set the copy/paste off-sets to zero in the main options panel! This makes for fast duplicating left/right model parts. OK, your model should look some thing like this:

(Two more lathes and we're done... anyone guess where we're going with this?)

Let's change the lathe sections to 12, and make a new tube like we did before. This time we want to close the back end with one of the alternate closure techniques. Draw a 4 CP spline and connect the inside 2 CPs to to wall of the tube. Select a tail CP and whack the <,> key, copy & paste, then translate (move) the new spline a tad, attach -- repeat 'til the rear is closed. See image below. OK, Why?

Remember from Basic Splinemanship I tutorial, connecting the end CPs of two splines creates one contiguous spline... Well, we wanted to make sure that didn't happen -- this method ensures nice peaked joints when we intentionally want them that way. Ok, now delete all the tails. Select our new tube, change views as needed and rotate this tube to match the direction of our two smaller ones, then hide everything else <h> key. If not in the front view then go to the front view <keypad 2> key. Notice that the closure splines are slightly diagonal, I want you to rotate the tube so that these splines are parallel to the X- Axis (should be Blue handle 15 degrees). See below, first panel:

Group select pairs of CPs from the side view and with the cursor keys move them towards the other end, as shown above, panel 2.

To be continued.... (soon)

If you learned something from this tutorial, please drop me an E-mail at Jeff Cantin
This is an important step, I track the number of visits to "thank you" notes, I need to know my time and my web space is well spent.

I have other tutorials linked from my hobby homepage. Give those a try too when you are ready.