Attached Link: http://www.ac3d.org/

BTW, if anyone is interested, you can get an overview of AC3D V6, and a 14-day time-limited trial at the above link. AC3D is a modeller only. It doesn't do much else. But it's simple and easy to use, it's shareware (relatively cheap) and includes a manual... (.PDF file). And it has greebles..:-))

This is a method to make a spiral staircase, in AC3D, for absolute beginners.

Some basic, introductory info:

When AC3D starts up, it defaults to "Group" selection and "Move" mode. That's just fine for now.
You can select objects you create by clicking on them. What you actually select depends on the selection mode (the top 4 buttons on the LH side).

The 4 modes are Group, Object, Surface and Vertex.

Once something is selected you move the cursor into the bounding box and the cursor will change shape. If you're in Move mode (default), the cursor will change to a "cross-with-arrows".

Click and drag to move something.

(This mini-tut. will only be using Move mode).
You can modify the size and shape of the box by dragging the bounding-box "handles" (the green squares).

You can also select by dragging the cursor to create a selection-box.
If "Select through" is off, then only visible things are selected. If Sel-thru is on then (especially in Vertex-selection mode) all vertice that are within the selection box are selected (visible or not), More on this later..

You can deselect by clicking on any unselected part in any of the views, or by selecting something else, or via the "None" button in the tool-bar at the top of the screen.

You'll see (and use) some of the above in the following mini-tut..

On to the tut...

1. Turn on Gridsnap if necessary. This helps ensure that the RH face aligns exactly wiith the Y-axis. Also, turn on "Select through" (this will be useful later).

2. Click the Draw Box Tool.

3. Draw the box. use the bounding-box handles to fine-tune your box (easiest done using the Front/Side/Top views). Make sure that one side touches the Y axis.

4. Also make sure (using the side view) that the box is exactly centred on the Y-axis (you will need to make sure your side-view has an even number of "units").

• All the playing around with the Y-axis alignment isn't strictly necessary, but makes thing a lot simpler later on..
• Re. the grid. There are actually 2 grids there, the one with dark lines and the smaller-scale one with lighter lines. The smaller one is the snap grid.
    Don't worry if your setup isn't the same as mine (I can't remember off-hand what the default is), but it shouldn't really matter.
    You can, if you wish, change the grid sizes via the menu File->setting, in the General tab. The top two boxes (Grid Major and Grid Minor) control these two grids. Mine are currently set at 1.0 and 0.1 respectively.

next.. making the step wedge-shaped.

1. Switch to Vertex selection mode.

2. In the front view, drag a selection around the top right vertex. Note that because "Select Through" is on, both the vertices (the near one and the far one) get selected.
      The info line above the front view should say "Vertices seldected:2". If it says anything else you've done something wrong, so undo (ctrl-z) the selection and try again...
   -  An aside, AC3D suports multiple undos, although there are some actions which cannot be undone or otherwise clear the undo list (saving in native file format is one of these, alas..)

3. Go to Menu->Vertex->Snap Together. The top Right 2 verts will snap equally towards each other, appearing as a single point (althought there are still 2 verts there - we'll clean that sort of stuff up later).
      The result will look a little odd...

4. Repeat steps 2 & 3 for the bottom right vertices.
      You should now have a nice, clean wedge-shape (see the BG of the pic..).

On to the fun bit...

This will probably take some experimentation to get right, especially the angle to rotate by.
If you've copied my shape exactly, (which may not be possible, I may not have given enough info for that), then the figures given in the pic should work.
If not, either be very good at trignometry, or play with the angle to see what works.
When doing that I usually just replicate once, and undo if the reult isn't right.
Note that the Replicator is a sort of macro, it actually does several steps in one. When undoing, you have to undo each step.
Or just delete the replicated object...

1. Switch to Object Mode. If your wedge isn't selected, select it now.

2. Go to Menu->Tools->Replicator.

3. Fill in the values.

Notes:

• Number of copies: Well that's up to you. As noted above, if you're fiddling about getting the rotation value right, then set this to 1. That way you only have 1 copy to undo, not lots..
• The Translation, Rotation and scale lines each have 3 boxes. These are X, Y and Z values (in that order).
• Translation. We're only going to be moving each replication upwards, so set x & Z to 0.
    Check the W(idth), H(eight) and D(epth) values displayed above the Side View. For the wedges to line up exactly, enter the Height displayed there into the Y box.
• Rotation (the fun one). Again, we only want to rotate about the Y axis, so that's the only place a value should be entered.
• Rotate about the origin. (That was why all the fuss of getting the original box lined up with the Y axis.
• Scale isn't used in this little exercise, so lave as 1.0, 1.0, 1.0.

When you're happy, hit "Go".
Instant (well nearly) spiral staircase:-))

Almost there.
But we need to do a bit of tidying up....

Tidying up.

When the Replicator did its stuff, it created a separate object for each wedge.
That may or may not be what you want.

To merge all the objects into a single object:

1. Switch to Object Mode if necessary.
2. Select everything (easiest done by clicking "All" in the toolbar above the Front view).
3. Go to Object->Menu->Merge

Done. A single object. But we're still not quite finished.

Remember when we snapped together the vertices to make a wedge? Those vertices doubled vertices were also replicated.
Plus, if the Y-translation for each wedge was exact enough, the point where will contain 4 identical verts.
To rectify, go to Menu->Object->Optimise Vertices...

And that's about it, really.
Save you file (if you haven't already) and File->Export in a format of your choice (I usually use .obj).

You may want to add a cylinder, move it so it's centred on the Y axis and scale it for a centre pole.
If you do do that, I strongly suggest giving it a different colour (from the strip down in the bottom left). This will make it a lot easier to add separate materials/textures later.

If the object is going to be used in Poser, you may need one extra step.
Fire up Poser and import the staircase. Is it "bloated"?
If you have Poser 6, then you may be able to get rid of this using the crease angle etc.

If not, then Run the .obj through Steve Cox's UV Mapper and split Verts (remember to save under a new file-mane).

It's taken me far, far longer to write all this and illustrate it than it did to create the staircase originally, but that's to be expected.

I know it's all very simple stuff, but I was aiming it with the "absolute beginner (in AC3D)" in mind.

Hope you liked it.

Cheers,
Diolma

PS: Any C'n'C regarding the way this tut has been laid out welcome. Was it informative? Did it show enough detail? Was it too cluttered? etc...