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Author Topic: "Solid" staircases  (Read 536 times)

SO3070

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"Solid" staircases
« on: April 07, 2016, 09:58:02 PM »
Hello,

would it be possible to create stairs not only by duplicating the treads, but also deform them so they go all the way down to the floor, something like the "box"-option in the 3ds Max straight stair object? Or even better: until they reach a spline curve to create an arch under the stairs? To clarify what I mean please have a look at the attached image. The part the girls is standing on would have treads on one side and be boxed up around, the staircase in front of her has an arch underneath.
Is it possible to create such things directly with RailClone?

Thanks,
Bob

Paul Roberts

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Re: "Solid" staircases
« Reply #1 on: April 08, 2016, 12:12:14 PM »
Hi Bob,

You should be able to achieve both those things with RailClone. Here's how:

Solid Staircase
1. To create a solid staircase, use a single tread as the segment and set the Deform mode to Stepped. Set the Alignment to Top.
2. Wire the segment to a Transform operator and export the Z Fixed Size property.
3. Wire an Arithmetic node to the Z Fixed Size property and change the mode to Expression.
4. Open the Expressions editor and enter XSplineCoords.z. This will now scale the segments between the RailClone gizmo's location on the Z axis and base spline.



Staircase with Arch

This is a little trickier because RailClone can't currently scale a segment between two splines. The workaround is to use two generators - one for the top of the stairs and one for the bottom. You then combine them using a clipping spline to slice at the point where they intersect. To do this:

1. Draw a spline for the stair angle but complete it so that it's a closed shape - like this

2. We're going to use this spline for both the path and for clipping so we need to tell RC to only put stairs on the angled section. To do this, select the spline segment and change the Material ID to 1, change the remaining segments to ID 2.
3. Create a generator for the top of the stairs and wire the spline to both the Spline and Clipping Spline inputs.
4. Go to Properties > Limits and activate material ID. Leave it at the default value of 1. This will now only create steps on the angled spline with the same ID
5. Add the tread segment and set the Deform Mode to Stepped and the Z Alignment to Top.
6. Adjust the Z Fixed transform to push the step above the spline, we're going to cut off everything below the spline in the next steps.
7. Change the generator's clipping mode to Exclude and set the axis to X or Y depending on the view you created your spline in. You'll now have the top of your stairs like this:



8. To create the bottom we'll do something similar. Create another generator and two new spline objects. Wire one to the Spline input and the other to the Clipping Spline input.
9. For the clipping spline, pick the same spline as we created in step 1. For the path Spline pick a spline to define the bottom of the stairs. The start and end points must align exactly with the top stairs spline.
10. Set the Clipping projection to X or Y and set the mode to Include
11. Add the step segment and set the mode to either Vertical or Stepped depending on the effect you'd like to achieve.



The final graph actually looks pretty simple:



As always, it's easier to see these things in action so I've attached a sample file with this example and a couple of other facade elements based on the use of the same technique.



I hope that helps, please let me know if you have any further questions.

Many thanks!

Paul
« Last Edit: April 08, 2016, 01:34:52 PM by Paul Roberts »
Paul Roberts
iToo Software

SO3070

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Re: "Solid" staircases
« Reply #2 on: April 08, 2016, 01:25:44 PM »
Hi Paul,

great, thanks a lot for this astonishingly fast, detailed and profound answer! That helps a lot, I still have to dive deeper in how everything is connected. It is interesting, that the facade examples do not use clipping at all, I will try to understand them as well but probably need a moment. :)

Just in case someone else wants to follow these instructions as well, here is what I as a beginner stumbled upon at first:
Solid Staircase:
The step Z-alignment has to be set to top, otherwise the expression does not work as expected.

Arch:
1. The first spline should be drawn in a side view (left, front).
3. Wait with wiring the clipping input until (7.), otherwise it is hard to set the other things since everything is clipped and therefore invisible.
11. If the arch-segments do not lign up with the treads, try to reverse the arch spline.

Again, thanks a lot!

Bob

Paul Roberts

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Re: "Solid" staircases
« Reply #3 on: April 08, 2016, 01:42:18 PM »
Hi Bob,

Glad we could help out, thanks for adding the extra tips. I've amended the first point to include setting the alignment.

Hopefully I can explain why the Facade elements don't use clipping. This is because they can be split into halves  horizontally, so I can just butt two arrays on top of one another. Stairs on the other hand, due to their shape, can't use this approach as the split has to be diagonal. So in this case I've used a clipping spline.



I hope that helps to clarify.

Many thanks!

Paul
Paul Roberts
iToo Software

SO3070

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Re: "Solid" staircases
« Reply #4 on: April 08, 2016, 01:57:35 PM »
Ah, I see, makes perfect sense, thanks for the clarification!

As I just retried to build it on my own, I forgot one thing in my beginner stumble-list for the solid staircase: The Fixed Size in the Transform operator is off by default and has to be activated of course. :)

Thanks,
Bob


TL1895

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Re: "Solid" staircases
« Reply #5 on: April 09, 2016, 02:22:53 PM »
good post, and of course, excellent answer!