Saturday, February 21, 2009

What’s New in the Revit 2010 API: Very Spatial APIs

One of the most exciting areas of potential API development is checking the building… Whether trying to determine if the egresses are short enough, or whether there is a nurses station close enough to each room, or just understanding how buildings, floors and rooms are modeled – there are a lot of things to check for. Historically, these things have been hard to check for – it was far easier to just look at a drawing than to try and figure it out.

But all that is beginning to change with some neat new APIs in 2010, which give you some tools to help understand the building and spatial relationships between objects.

Shooting Rays

One of the classic CAD solutions to these kinds of problems is “shooting rays” through your model… That is, set a point and a vector, then see what that “ray” hits. This was kind of possible with some creative math prior to 2010 – but it’s both better and easier now in 2010.

The new mechanism:

ReferenceArray =
Document.FindReferencesByDirection( origin, direction, View3D)

The new method returns back an array of references – and the reference class has been upgraded to include:

  • Element
  • Type of Reference (Surface hit, Element hit, Edge, Foreign, Mesh)
  • GeometryObject of the hit
  • XYZ location of the hit
  • Distance of the hit from the origin (“Proximity Parameter”), UV location of the hit on a surface (if appropriate)

Important Note: The View3d that you specify controls a few things – first, if you’ve got elements or categories hidden, those do not seem to be “hit”… Also, remember that if you’ve got model phases, the ray will follow the phase of the view.


Still, it’s a great new feature for those who are trying to use the API for any kind of building analysis.

Where am I?

The other enhancements in the category of spatial awareness relate to being inside a particular architectural room or MEP space. If you want to test if a given point is in a known room or space, you now have:

  • Room.IsPointInRoom( xyz )
  • Space.IsPointInSpace( xyz )

Conversely – if you don’t know where a particular XYZ point is at all, you can ask:

  • Document.GetRoomAtPoint (xyz)
  • Document.GetSpaceAtPoint (xyz)

I think these enhancements are also critical… while FamilyInstances have long known which room they were in – these API enhancements give a great variety of additional power for analyzing buildings.

What’s New in the Revit 2010 API: Element Enhancements

(Part of the What’s New in the Revit 2010 API series)

As with each release of the Revit API, there are a ton of enhancements to the “Elements” area of the Revit API. Whether it’s new capabilities on existing elements, or new Element classes to make Revit elements more identifiable and understandable – enhancements here are a big deal.

Elements and Materials

One of the features I’m most excited about is the new Element/Material part of the API. In the past, trying to do material take-offs with the API was tough – especially if the designers were using Split Faces (which almost everyone does). You pretty much had to export out to ODBC or schedules to Excel in order to extract what you needed. But no more.

image This room floor has been divided by a split face – with one of the sides being carpet and the other tile.

In Revit 2010, every Element has a Materials property to show all the materials associated with an element. Further, you can call Element.GetMaterialArea( Material ) or
Element.GetMaterialVolume (Material)

to get the area or volume of material for that element. With this, people trying to do material take-offs through the API should be in far better shape!

Element Hiding

For a number of releases, Revit has supported the hiding of individual elements on a view-specific basis. While great for designers, it did pose occasional challenges for developers. Now, the API offers up:

Element.CanBeHidden ( View v )
Element.IsHidden( View v )
as well as:
View.Hide( Element e)
View.UnHide( Element e)

This should give developers powers similar to what you can do in Revit interactively (that fairness which every CAD developer yearns for :) ).

Family Enhancements

There are few enhancements with Family and FamilyInstance elements:

  • Family.IsInPlace (this was possible heuristically in previous releases – but it’s always better to make it obvious)
  • Family.IsCurtainPanelFamily (because of the special additional properties – it’s good to know this directly)
  • FamilyInstance.IsSlantedColumn (another situation where there are special additional properties)
  • FamilyInstance.Space  (similar to familyInstances knowing which Room they reside in, now they know which space they reside in – very useful for MEP families!)

New Element Classes

The following classes are new in 2010:

  • Alignment
  • AreaScheme (see below)
  • BasePoint
  • Control
  • CurveByPoints
  • CurveElement
  • DividedSurface (with an amazing amount of depth!)
  • Form (representing all of the Family solid content, and also with a huge amount of depth)
  • ImportInstance (used for DWG imports, etc)
  • ModelText
  • PointOnEdge
  • PointOnEdgeEdgeIntersection (I think you might need to have a PhD or be Russian to understand this :) ).
  • PointOnEdgeFaceIntersection
  • PointOnFace
  • PointOnPlane
  • ReferencePoint
  • ReferencePointArray
  • SpacingRule (structure and grids)
  • SweptBlend
  • SymbolicCurve
  • TopographySurface (with an “AddPoints” method, no less)


There appear to be a few enhancements to Area elements that are of note:

  • New AreaScheme element (this typically is set for “Rentable”, “Gross” but also apparently has some new BOMA settings for facilities management people)
  • Areas have a link to their scheme
  • ViewPlans have a link to the AreaScheme (where appropriate)


Dimensions also seem to have some upgrades in 2010. In particular:

  • Dimensions have DimensionSegments
  • The “Locked” property (read/write) has been added

Other Miscellaneous Enhancements

A few others that I couldn’t categorize:

  • Blends now have access to Profiles, Offsets and VertexConnections.
  • CurtainGridLines now have ExistingSegmentCurves
  • Grid.ExtendToAllLevels method
  • GridNodes
  • GBXMLParamElement now has an ExportComplexity object associated with it which contains all sorts of things to control how GBXML is exported (including, for example, how to handle Shading Surfaces).
  • ModelCurve now exposes:
    • IsReferenceLine
    • SubCategory
    • TrussCurveType
    • Visibility
  • Mullion.LocationCurve
  • Opening exposes IsTransparentIn3D and IsTransparentInElevation.
  • Path3D.AllCurveLoops

Two that I’ll be writing about a little later:

  • Room.IsPointInRoom (XYZ)
  • Space.IsPointInSpace( XYZ )

A few items seem targeted at making it easier to get geometry references and planes:

  • Level now exposes a PlaneReference (to make things easier)
  • ReferencePlane.Reference
  • SketchPlane exposes:
    • Reference
    • IsSuitableForModelElements
  • View.SketchPlane

Wow. Again – there’s enough in these enhancements, new classes and more to keep us busy for quite some time.

What’s New in the Revit 2010 API: Element Creation

(Part of the What’s New in the Revit 2010 API series)

For some people, the measure of a CAD API is always how many different types of elements it can create. Revit got off to a slow start in this category, but it continues to get stronger.

In this release, the new Revit API capabilities seem divided into:

  • A significant amount of new MEP element creation
  • A little bit of new Structure / Rebar options
  • A significant amount of new capabilities around family content creation.
  • A few very interesting things around the new freeform geometry and divided surface modeling in Revit 2010.

All in all, Revit can now create 70-100 different types of elements (depending on how you count the family content-related things).

What’s New for MEP Creation?

Here are the new MEP-oriented creation capabilities:

  • Duct
  • Elbow
  • ElectricalSystem
  • FlexDuct
  • FlexPipe
  • MechanicalSystem
  • Pipe
  • PipingSystem
  • Cross Fitting
  • TakeOffFitting
  • TeeFitting
  • UnionFitting
  • Wire

(not being very MEP-savvy myself, I can’t add any real commentary to them other than to say it looks like an impressive list).

What’s New in Family Content Creation?

This whole area is new and exciting…

  • Solid Forms
    • Blend
    • Extrusion
    • ExtrusionForm
    • Form By Cap
    • Form By ThickenSingleSurface
    • Loft
    • Revolution
    • SweptBlend
  • Supporting Elements
    • Angular Dimension
    • ArcLength Dimension
    • Linear Dimension
    • Radial Dimension
    • Symbolic Curve
    • Control
    • Alignment (this looks interesting)
    • Vertex Index Pair (this is a construct which defines how different profiles in a blend link together, I believe)
    • Family Symbol Profile
  • More Elements
    • Openings
    • Model Text
  • Freeform Modeling / Surfacing
    • Curve By Points
    • Divided Surface
    • Reference Point

A Brief Story on Reference Points

A year or so ago I pinged Emile Kfouri, the Revit Platform Product Manager about why there were no “Points” in Revit (I can’t recall why I needed them – but I do know how old-time CAD people’s heads look like they’re going to explode when I say that they don’t exist). He said “Points are not BIM” – and I came to agree with the statement, in general (not that Lines are BIM – and they were prevalent in Revit still). In any case – while they’re not BIM, they are quite handy for building things – and it’s nice to see them in there.

A Few More…

Finally, there are a couple last additions and changes…

  • Rebars defined by RebarShapes
  • Hermite Splines (these are one of the building blocks of the new freeform modeling capabilities)
  • Plane from Curves
  • Topography Surface (Now this looks very interesting – just pass in an array of XYZ points and get back a surface? I haven’t had a chance to try it out yet – but it should be cool!)


Image: a spline-controlled surface with control points that can be dragged/modified.


All in all, this release presents a great deal of new capabilities around Element creation… certainly enough to keep most of us busy for the next year until Revit 2011 comes out!

Thursday, February 19, 2009

What's New in the Revit 2010 API: User Interface

From the (What's New in Revit 2010 API series).

As you may know, Revit 2010 brings the Ribbon-style User-Interface to the world of Revit. Similar to bringing the Ribbon to Microsoft Office or AutoCAD - this has far-reaching effects on how users will navigate Revit.

For better or worse, ExternalCommands and ExternalApplications will be shoe-horned into the new Ribbon concept.

How it Works

First, if you have any "Add-ins" of any kind, the "Add-in" tab is visible in Revit.

Second, any ExternalCommands which previously were on the Tools > External Tools menu are now on the Add-Ins menu under the "External Tools" pulldown-button.

Third, there are a number of "constructs" for how you can customize the ribbon. Unlike AutoCAD's WPF Ribbon UI, you are limited to just a couple of UI elements.

The key elements are:

  • RibbonPanel - creating an "area" to contain your application

  • Pushbutton - a single Pushbutton command

  • PulldownButton - a button which drops down a list of commands

  • Separator - basic separation

Both Pushbuttons and PulldownButtons can have large (32x32) icons and small (16x16) icons (not shown above). The large icon is always displayed on the button, while the small icon is only shown if the user adds the button to the "Quick Access Toolbar" - which is always available.

Autodesk also released a 29-page document describing how icons should be created to fit in with Revit (who knew it could be so complicated? :) ).

Existing Applications

The existing APIs that applications use to create both top-level menus or toolbars have disappeared - so you MUST migrate to this approach.

Summary Opinion

While I think that it's great that the Ribbon has come to Revit - I really like it... The UI straightjacket that we've been put in with the UI is a little tight... It would be nice if we could at least do stacked buttons like the rest of Revit.

(Editors Note: Stacked buttons, 2 or 3 high - was added in the API after this was written)

It's also a little unfortunate that everything external is confined to the "AddIns" tab - both because we used to be able to have "top-level" menus, but also because if you have a lot of applications loaded, the real-estate may get crowded.

What's New in the Revit 2010 API: Finally Families!

(Part of the What's New in Revit 2010 API series)

Probably the biggest single improvement to the Revit API in 2010 is a wide variety of enhancements to supporting Revit Families - and it's been a long time coming.

Until now, the support for families has been spotty - for example, you could open family files as documents - but you couldn't see the types inside them - or really do anything with them.

Autodesk has implemented a dizzying amount of capabilities to help with:

  • Analyzing Families

  • Creating new Families (geometry, parametrics and all!)

  • Reading and Writing Family Types, parameters, and even formulas

  • Ability to examine Families embedded in projects

  • Read/Write Family Element Visibility

  • Control the loading behavior of families
Personally, after doing a number of Family manipulation projects which had to be done with Journal Files - I'm excited to be back dealing with the API!

Enhanced Document class
The core concept of working with families in the Revit 2010 API is the improved "Document" class. The Document class still represents both Project and Family documents, but it has been enhanced with the following properties and methods:

  • EditFamily( family) - similar to context-menu Edit Family command

  • FamilyManager (provides access to the types, parameters, and formulas related to the family)

  • OwnerFamily - to deal with nested family components

The Family Manager is able to do a wide variety of tasks, including full control of adding, removing and renaming types, adding and removing parameters, and setting values and formulas.

Creating Solids

Creation of elements will be covered in more depth in another post - but suffice it to say there is an impressive list of things that you can programmatically create through the new APIs, including:

  • Extrusions

  • Blends

  • Sweeps

  • Loft

  • Model Text

  • Openings

  • Revolutions

  • Dimensions

  • and much more

Visibility Settings

For those of you who are not familiar with content building, one of the most critical topics to "get right" when building content is the visibilty settings:

Each element in a family has visibility settings - both which levels of detail it appears in as well as whether it appears in different types of views. These options are critical to building good content. For example, if you have intricate details in your family, consider if they should only be shown in "Fine" detail views. Also, if you have 3D solid content, one alternative is to NOT show the 3D solid in Plan views - instead, you would use 2D linework in Plan View. These approaches can make a SUBSTANTIAL difference in the performance of Revit - particularly as your building model grows.

While there had been undocumented parameter access to this information before, the new FamilyElementVisibility class makes this information easy to access for each element in a family.

Loading Control
If you've ever written an application that loads families into a project, you may have run into the problem of what happens when the family already exists in the project (particularly if you're using shared families). While the "DialogBox" event controls used to give a poor-but-workable method to suppress Revit's pop-up dialog boxes, the new loading methods give far better control over what happens.

The new LoadFamily method signature:

Family = Document.LoadFamily( string path, IFamilyLoadOptions options );
Family = Document.LoadFamily( Document familyDocument, IFamilyLoadOptions options);

The IFamilyLoadOptions, as implemented by the RevitUIFamilyLoad class, give you events for family loading as well as specific behavior control for whether to update the family, and whether to override parameters.

What Can You Do With All This?

There are a variety of capabilities that these features open to you... First of all, I suspect that a variety of new content tools will become available to better manage your content. If you manage a great deal of content, and need to make large-scale changes to content, these features will make it happen.

It IS possible now to extract project families back to RFAs - as well as doing better comparisons than previously possible between "embedded" families and standalone families.

Another big step for Autodesk - they now allow you to use the API insert a DWG file into a family. This had previously been deliberately disabled.

Hypothetically speaking, this means that you could possibly crank out thousands of families based on existing DWGs. But before you consider doing this - let me be among the voices saying - DON'T. Our research indicates that families created using DWG files are fundamentally terrible - they are "heavy", "slow", and "dumb". Almost all firms using Revit have discovered this - and are systematically removing these families from their library. Doing content correctly would be a great other post - and the API now gives you the tools to do things right... Please try to do the right thing!


Wednesday, February 18, 2009

What's New in the Revit 2010 API: General Changes

(Part of the What's New in Revit 2010 API series)
In this post, we'll cover a few quick topics about general changes to the Revit 2010 API.

.NET 3.5 and Visual Studio 2008 SP1

First, the 2010 release has a new platform requirement for developing Visual Studio solutions - .NET 3.5 for users and Visual Studio 2008 SP1 for developers. What does this mean? Several things:

  • First, every user of Revit 2010 will have the .NET 3.5 Framework pre-installed, taking care of the pre-requisite issue.

  • We can leverage the new technologies available in .NET 3.5, including: Windows Presentation Foundation (WPF) for new look-and-feel, Language Integrated Query (LINQ) for easy access to data from databases, XML or the Revit model.

  • Potentially improved deployment options with .NET 3.5 SP1, which resolves some issues that made it difficult to put Revit Plugin DLLs in a centralized network location.

As a developer, I also appreciate the ability to take advantage of the newer features of Visual Studio, including the built-in Unit Testing framework and language features like the new "var" keyword - where Visual Studio figures out variable types for you!

Compatibility with Previous Versions

The nature of the changes to the RevitAPI makes it likely that old applications will be broken in 2010, and will require re-compiling and some changes to make them work with 2010.

It is possible, if your ExternalCommand does not make use of any objects or properties that have changed, that the existing DLL will work - but I'd say that any ExternalCommand of any complexity is unlikely to work without changes.

VSTA 2.0

We will talk about VSTA (Visual Studio Tools for Applications - Microsoft's replacement for VBA - Visual Basic for Applications) and Revit separately - but this version of Revit includes the 2.0 version of VSTA.

What's in a Name?

I've historically been curious about the directory that Revit gets installed in, i.e. "C:\Program Files\Revit Architecture 2009". It always seemed like Revit has held onto the "Revit" folder name while the other Autodesk products were all being standardized to be called "Autodesk _____".

So whether they just finally got around to it, or whether there's deeper intrigue - as of Beta 1, the product is now called "Autodesk Revit Architecture 2010", with the folder name to match.

Ok, this post was a little dry and boring - but I felt like these things had to be said up front... I promise it will get better from here :).

What's New in the Revit 2010 API

One of my favorite blog topics of the year is here - the "What's New" posts, describing the new capabilities of the API (application programming interface) for Revit.

In this series of posts, I'll try to lay out both what's new and what it might mean for you.

Since introducing a small .NET API in Revit 8, the API has doubled in size for each release. Obviously, that's not sustainable the bigger the API gets - and while I'm not sure of the "actual" size increase of the 2010 release, I can say that it's impressive in both size and thoughtfulness.

There is so much new, that we will break up the posts as follows

Whew! Even breaking it up into this many pieces, these are still going to be some large topics. I'd better get started.