Revit Repeaters - RTC 2013 Competition Entry

Revit Repeater artwork

This image was part of my  entry for the drawing competition at RTC 2013, in the innovation category.  It was created using 100% Revit, without the use of Dynamo or any add-in APIs.  It was done to demonstrate some of the capabilities of the new "Repeater" command that was added to Revit 2013.

The museum building wall was created as a mass family, consisting of a curved spline in plan, extruded upwards to represent the outside facade;  its surface was divided into a rectangular grid.  A five point adaptive component panel was placed on one rectangle of the grid, with one of its points snapped to a common control point off the surface of the wall;  the panel was then repeated across the entire facade;  the size of the window in each panel was controlled by its distance from the control point - using the "reactor principle" described on Zach Kron's Buildz blog (a complex formula defined a sine-wave pattern for the change in window size).  Hopefully I will get time to document the technique on this blog eventually!

The artwork on the wall was done using two-way repeater pyramids that change shape depending where they are in the pattern - refer to how-to-schedule-panel-locations.

The people were single-point adaptive components consisting of lofted circles that had parametric diameters at various heights up the body, used to create different body shapes for each family type. The people outside were turned into repeaters by hosting six of them on divided splines, then using the repeat command - thus forming queues of people snaking into the museum entrance.

The signage on the roof of the museum was done with adaptive component (model text) repeaters that automatically rotate to face the camera - refer to my Mona-lisas-eyes-follow-revit-camera blog post.

The ground surface texture was done by creating a divided surface with slightly distorted adaptive components placed in a pattern of four and then repeated.

For more on this competition entry see the outdoor image of the museum

Revit Repeaters Index Page

When Revit v2013 was released it gave us the first version of a great new feature:  Repeater.  Repeaters are an alternative way of creating arrays in Revit, but they only work in the conceptual massing environment (Adaptive Components and Massing) where the tradional Revit array tool is not available.

I presented a paper on the topic "Divide and Conquer: Adaptive Components in Revit 2013"  at Revit Technology Conferences in May 2012 (Wollongong, NSW), June 2012 (Atlanta, USA).  When I submitted the abstract v2013 had not been released so I wasn't able to use the word "Repeater" in the title!  I followed this up with further presentations at RTC in 2013: "Fractal Fun with Revit Repeaters" - May 2013 in Auckland, July 2013 in Vancouver and September 2013 in Delft (Netherlands).  In the process of researching these topics I have tried to explore the capabilities and also to uncover the mysterious rules of Repeaters.  I have written a number of blog posts on the subject, so it might be useful to list those here.

Revit Repeater Index

• New Divide and Repeat Tools at RTC 2012
• RTC 2012 - Repeaters for Space Planning videos 1
• RTC 2012 - Repeaters for Space Planning videos 2
• RTC 2013 - Fractal Fun with Revit Repeaters
• RTC 2013 - Modeling the roof structure of Santiago Calatrava's Gare do Oriente (Lisbon):
• Step 1  Creating the rig for one structural column
• Step 2  Putting roof panels on top of the rig
• Step 3  Creating the structural elements and placing on the rig
• Step 4  Adding Struts to the structure
  Step 5  Assembling the Array of Structural Columns
   

• RTC 2013 Europe - Fractal Fun Report
• RTC 2013 NA - Drawing Competition Entry - Indoor image 

• RTC 2013 NA - Drawing Competition Entry - Outdoor image

Repeater Theory

• Single Point Repeater Patterns
• Multiple Point Repeaters on Divided Surfaces
• Two-Point Repeaters on Multiple Hosts
• Step Pattern repeater - part 1
• Step Pattern repeater - part 2
• Indent Repeater on a Divided Surface 
• Schedule Repeater Location within Pattern 
•    Alternative Method to Schedule Repeater Location
• Circular Repeater Geometry
• Divided Path / Surface Node Visibility (Hidden Commands)
• Instance Properties of Repeater Components
• Selecting Individual Components in a Repeater  
• 'Remove Repeater' - Dissolve a repeater so you can use it to create a form

Fun Examples

• Flexing Star Repeater Adaptive Component - videos
• Repeater Star Patterns

Adaptive Components Index

Adaptive components are a vital part of Repeaters, so here are a few posts on them as background:

• Traditional Family Editor vs Adaptive / Conceptual Massing Environment
•     A Dozen Reasons Not to Use Adaptive Components
•     Reasons to Use Adaptive Components
• Swept Blend using Profile in Adaptive Component
• Egress Path using Adaptive Components (Life Safety Plan)
• Egress Path (Update) and Shape Handle Points
• Mona Lisa's Eyes Follow The Revit Camera
• Adaptive Component Origins
• Zero Length Lines are Possible in Adaptive Components

 

Before Repeaters - Traditional Revit Arrays

 

• Random Colour Patterns

• Reactor Principle & Colour Patterns
• Two Directional Arrays - part 1
• Two Directional Arrays - part 2 
• Two Way Array Patterns with Voids

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).

How to Schedule Panel Locations on a Flat Rectangular Surface in Revit

This post demonstrates how it is possible to schedule repeater component cell numbers on an orthogonal pattern within the Revit Conceptual Massing or Adaptive Component environment:

To set this up, first you need a rectangular surface, which has been divided; then you need to place an adaptive component onto the node(s) of the surface; once arrayed in two directions using the repeater function you can schedule the cell (column and row) numbers on the divided surface.  Of course it isn't that simple - the adaptive component has to be aware of its location relative to a fixed point, by doing some calculations:

• The example here is perhaps a little more complicated than it needs be to demonstrate the principle, but it does a few other fun things too.
• The adaptive component to be repeated must be set to “Shared” so it can be scheduled;  it needs to use shared parameters so they can be scheduled too.
• In this case it is a 5 point adaptive – one for each corner of the base of a rectangle placed on each cell of the divided surface;  the fifth point works as a “Reactor” – it tracks the distance of the component from a base point.
• This rectangle is made more interesting by having a pyramid on top that has an apex that moves depending where it is in the repeater pattern.

To create the adaptive component:

1.  Start a new generic adaptive family.

• Place four points in a rectangular shape;  make them adaptive

• Join the four points with reference lines (make sure 3D snapping is on)

2.  Set up the geometry for the pyramid (optional):

• Place a point on each line  (if correctly hosted it displays as a small point)
• For each point assign a (Shared) parameter to its “Normalised Curve Parameter” – for the notional Y axis point, make it “Y_Ratio”;  its point on the opposite side will have its “Measure From” value set to End, rather than beginning, so that they line up.
• Assign a parameter “X_Ratio” to the notional X axis points (one from beginning, one from end, depending on which direction you drew the reference lines)

• Join the two opposing points with reference lines
• Place another point on one of the linking reference lines
• Select the point and the option bar should show:

 

• Click on “Host by Intersection”, then select the opposing reference line;  it should move to the intersection of the reference lines
• Set the “Show Reference Planes” property of the point to Always.
• Set the work plane to the horizontal plane of the hosted intersection point (it only shows as a single line)
• Place another point on top of the one on the intersection (ensure 3D snapping is on);  ignore the error message about duplicate points;
• Select the new point and drag it up in the zed axis – its ”Offset” property should change.  If you are lucky, it should be a positive value (if it is zero, then the workplane or hosting went wrong);
• Assign a “Height” parameter to it – if it was a negative value you’ll need to assign an interim parameter then convert it to positive with a formula, for the end user to understand.

• This point becomes the apex of the pyramid;  
• Join the point to the four corners of the base with four reference lines;
• Flex the X_Ratio and Y_Ratio and Height parameters
• Create a Form (surface) on each of the four sides of the pyramid

3.  Setting up the “Reactor” controls (Important):

• Place a fifth adaptive point to the left of point 1 (bottom left corner of rectangle)
• Use a reference line to join it to point 1
• Join points 5 and 4 (Bottom right corner of rectangle) with another reference line – to create a triangle of lines.
• Place 3 dimensions between the adaptive points 5 & 1, 1 &4, 4 & 5 – for each one make sure to set the relevant reference line as the work plane for the dimension;  it is vital to snap the dimensions to the adaptive points, rather than to line ends, surface corners etc (if not then you can’t use the dimensions later on in formulas)
• Make each dimension as a reporting instance parameter, for use in the “cosine law” in trigonometry.  We need to calculate the angle in the triangle
• The Cosine Law for calculating an angle when 3 sides are known, is:
  Angle γ = Arcos( (A² + B² - C²) / 2AB)
• Revit version of Cosines formula:
  Angle γ = Acos( (A^2 + B^2 - C^2) / 2*A*B)

• To work out the X and Y components of the distance “A” between points 5 and 1, use trigonometry:

• This calculation assumes that the angle of the line between P1 and P4 is orthogonal – so it only works with a rectangular repeater pattern.

4.  Calculation of column and row numbers:

• This requires knowledge of how many rows/columns there will be in the repeater, and the overall size of the repeater

• Parameters for these need to be built in to the component as shared parameters (for scheduling), as shown below;  these can subsequently be linked to the parent family parameters for these values.
  X Number and Y Number should be integers (count of repeats in each direction)
  Column Number and Row Number should also be integers.
  X Ratio and Y Ratio should be number parameters
• You may need a couple of checks to take care of when it has zero values for the distances.

5.  Creation of the repeater:

• The pyramid family needs to be loaded into another family that can support a divided surface – this could be an adaptive component, a mass family or an in-place mass family in a project.  In this example it will be an in-place mass family.
• Load the pyramid into the project
• Start an in-place mass family
• Draw a rectangle of reference lines,
• Give the rectangle dimension parameters of Length and Width
• Generate a form (surface) from the lines
• Select the surface and Divide Surface 
• Make the nodes visible on the surface (Surface representation)
• Assign parameters to U Number and V Number on the surface

• Place a point just to the left of the bottom left corner of the surface – this will become the control point for measuring distance.  It is important for getting the “Reactor” effect working.
• Place an instance of the pyramid component by snapping the first four placement points onto four adjacent nodes in the same order as you originally created the adaptive points (say clockwise);  place the fifth point on the external point – it is vital that it does not go onto a node of the surface

• Link 4 parameters to equivalent parent parameters:
  Y_Number to     V Number
  X_Number to     U Number
  TotalX  to  Length
  TotalY  to  Width
• Hide the nodes on the surface (Using Surface Representation - they cannot be controlled by any view settings)
• Select the free control point and move it very close to the bottom left corner of the surface.
• Select the Pyramid and turn it into a repeater 
• All being well, the pyramid will array itself over the whole surface, but each instance will look slightly different as the apex point is changed depending on its distance from the control point in the bottom left corner.  If not, it could be caused by a problem with the component itself, or else the fifth adaptive point might be hosted on the same point as adaptive point one, in which case it would move with it.
• Select (tab) any one of the pyramids;  it should display properties including its correct column and row number

• Finish the in-place mass family

6.  Create a generic Schedule:

• Add the column and row numbers, and any other parameters you require
• You will be able to edit the values for Comments and Mark, but no other instance values

• If you edit the mass family, it allows you to manually select any of the components in the repeater.  Then you can set it to “No Component” or to any other 5 point adaptive component.

When you edit the mass family, the schedule temporarily goes blank.  Sadly this means that it is not possible to drive the geometry from the schedule.  However, it does make it easier to identify and label components in a schedule – useful for adding and editing Mark values to match column and row numbers.

This technique will not work with a curved surface because it all works by calculating the actual distance from the control point to the BL corner of the pyramid and relating that to the overall length of the surface.  It will only work on an orthogonal divided surface, unless you are a mathematical genius and can write formulas to handle more complex geometry!