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Thursday, 28 November 2013

Geometric Patterns from Parametric Revit Stars

In my previous post I showed how to make a parametric star in Revit - one that has a variable number of points.  Here are some examples of how that might be used in a parametric pattern.  I have shown something a little like this previously and also in my RTC 2012 presentation, but that was done using a fixed number of points in the star, although it changed shaped parametrically.

Repeater Star Patterns in Revit

Since the parametric stars are made as adaptive components, they can be placed on a node of a divided surface (in a conceptual mass or another adaptive component)
Once the star has been placed it can be arrayed using the "Repeater" command to form a geometric pattern

By changing the radius of the circular rig in the adaptive star, it changes the size of the star and hence the pattern
Once the stars overlap it gives a completely different effect

Going back to the original size, the number of points on the star can be changed.  however, a five pointed star does not result in an interesting pattern once they overlap each other.  Likewise, 4 or 3 pointed stars don't look good (crosses and triangles)
Increasing the number of points to seven, does work reasonably well, although it looks a bit messy as the overlap increases!

An eight point star works well on a square grid pattern:

You can also change the background grid on the divided surface.  In this example one of the grids is rotated by 30 degrees:

The resulting patterns can be triangular or hexagonal in nature:
Just by changing the size of the star (radius of underlying crcle) you can get radically different patterns.

I hope that someone finds a use for this flexible way to create parametric patterns in Revit (2013 or later).

Sunday, 3 November 2013

Circular repeater geometry in Revit

In previous posts I have described how easy it is in Revit to use a circle as a rig to host regular geometric shapes like squares and hexagons.  It occurred to me the other day that circles would also be ideal hosts for parametric stars;  put that together with Repeaters and you get some interesting possibilities . . .

Here is how to create a parametric star:
• Create a new adaptive component;
• Place a point at the origin; make its reference planes visible
• Set the horizontal ref plane as the work plane
• Place a reference line circle onto the point
• Make its radius dimension into a parameter
• Select the circle
• Divide Path
•  It will create a divided path on top of the circle with 6 nodes
• Place two points, and make them adaptive
• Place a line between the points, remembering to enable "3D Snapping" first
• Save the second family (eg. as "AC 2pt Line")
• Load it into the first family
• Place one of the components onto two non-adjacent nodes

• Select the two-point component and click on the Repeat command
• You should end up with a triangle
• NB.  if you placed the two-point adaptive line component onto adjacent nodes you'd get a hexagon
• Actually, a triangle is only half of what we want, but we need to backtrack to get the correct result - so, UNDO the repeat command
•  Select both lines and click on Repeat
•
•  You should end up with a six pointed star, which is now a "Repeater"
• Select the divided path, and change the number of nodes to 5, giving you a five pointed star
•  Change it to 4, which gives a cross (not so useful)
•  Change it to 3 for a triangle
•  Change it back up to 7
•  And then to 8 - this gives an eight pointed star that could be useful in tiling patterns when repeated itself on a divided surface
•  As the number of nodes increase, the shape becomes closer to a circle
• Now all you need to do is turn the number of nodes into a parameter to get yourself a one-point adaptive parametric star component
• Oh, one more thing - you need to make the nodes of the divided path not visible otherwise they will show up when this component is placed in a project or another family

How useful is this going to be?  We'll investigate that in a future post . . .
Here is one possible use - geometric patterns