Understanding the Alignments and Profiles API in AutoCAD® Civil 3D® Isaac Rodriguez Sr. Software Engineer

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About the Presenter Isaac is a senior software engineer at Autodesk, and current software development lead of the AutoCAD® Civil 3D® API. Isaac has been with Autodesk for almost eleven years working in different products and technologies like AutoCAD Raster Design and AutoCAD Civil 3D. He has 20 years of software development experience including six years with Microsoft® .NET technologies. Contact me through email: isaac.rodriguez@autodesk.com Follow me on Twitter: @CivilDev Read my blog: http://civilizeddevelopment.typepad.com

About the Audience Tell me a little bit about you. Software Development implementing Civil 3D applications Civil Engineer writing automation scripts and internal tools Are you using .NET? Which .NET language you prefer?

Class Summary This class covers the basics of the Alignments and Profiles .NET API in Civil 3D. It also dives into the structural components of Alignment and Profile objects and their composition. Finally, the class demonstrates how Alignments and Profiles can be manipulated by changing parameters in their components.

Learning Objectives At the end of this class, you will be able to: Understand the structure of the Alignment and Profile objects Access to Alignment and Profile entities through the API Working with Alignment and Profile Entities according to their type Working with Alignment and Profile Entities and their constraints Complete the C3D API Challenge!!!

Structure of Alignment and Profile Objects

Alignments and Profiles Two dimensional, linear objects Composed of other two dimensional, linear objects (Entities) Alignments represent different model features Profiles represent elevation points along an Alignment Structures are similar but representations are different

Alignment Entity Sub-Entity Alignment Structure Alignments contain Entities Entities contain Sub-Entities Sub-Entities different from Entities Alignment Entity Sub-Entity

Alignment Entities Entities have a type Type identified by EntityType property (AlignmentEntityType enumeration) Object class does not identify entity type Basic Entities contain 1 Sub-Entity Composite Entities contain 2 or more Sub-Entities Entities have constrains

Basic Alignment Entities Contain a single Sub-Entity Lines (Tangents), Arcs (Curves), and Spirals Entity Entity Class Entity Type Line (Tangent) AlignmentLine Line Arc (Curve) AlignmentArc Curve Spiral AlignmentSpiral

Composite Alignment Entities Entity Entity Class Entity Type Spiral-Curve-Spiral AlignmentSCS SpiralCurveSpiral Spiral-Line-Spiral AlignmentSTS SpiralLineSpiral Spiral-Line SpiralLine Line-Spiral LineSpiral Spiral-Curve SpiralCurve Curve-Spiral CurveSpiral Spiral-Spiral-Curve-Spiral-Spiral AlignmentSSCSS SpiralSpiralCurveSpiralSpiral Spiral-Curve-Spiral-Curve-Spiral AlignmentSCSCS SpiralCurveSpiralCurveSpiral Spiral-Curve-Spiral-Spiral-Curve-Spiral AlignmentSCSSCS SpiralCurveSpiralSpiralCurveSpiral Spiral-Spiral (*) AlignmentSCS or AlignmentSTS SpiralSpiral Spiral-Spiral-Curve SpiralSpiralCurve Curve-Spiral-Spiral CurveSpiralSpiral Curve-Line-Curve AlignmentCTC CurveLineCurve Curve-Reverse Curve AlignmentCRC CurveReverseCurve Curve-Curve-Reverse Curve AlignmentCCRC CurveCurveReverseCurve Entity type MultipleSegments not used nor supported (*) AlignmentSCS used if entity between two lines and AlignmentSTS used if entity between two curves

Profile Structure Profiles contain Entities Profile Entities are Simpler Lines (Tangents) Arcs (Circles) Parabolas Symmetric Asymmetric Entities have constrains Entity Entity Class Entity Type Tangent ProfileTangent Circular ProfileCircular Parabola Symmetric ProfileParabolaSymmetric ParabolaSymmetric Parabola Asymmetric ProfileParabolaAsymmetric ParabolaAsymmetric

Accessing Alignment and Profile Entities

Entities Collection < IEnumerable > Accessed through Entities property Interface to access entities Implements IEnumerable for AlignmentEntity Entities enumerated by ID ID depends on alignment creation Time for some Code

Entities Collection < EntityAtId() > FirstEntity and LastEntity provided by collection EntityBefore and EntityAfter provided by AlignmentEntity EntityAtId() retrieves entity Suitable for sequential and direct access Some More Code

Alignment Entities Collection < GetEntityByOrder() > Zero-based index Less-than Count property value Raises exception with unconnected entities Not suitable for enumeration Use for direct access And More Code

Working with Entities based on Type

Alignment and Profile Entities by Type Entities have a type Leads to complex logical code Prefer abstractions and polymorphism

Entity Abstractions Create you own entity wrappers Separate wrapper creation from processing Provide interface related to requirements Use virtual functions for specialized functionality (polymorphism)

Function Objects (Functors) Objects that work like functions Flexible and highly customizable Represent application processes

Implementing ‘ExportAlignment’ Command Function Object to export information Customizable order Customizable output target Entity wrappers responsible for own information Logic to identify entity in Factory class Let’s look at some code

Working with Entities Constraints

Constraint Types Tangency Constraints Entity Definition Constraints Relation between entity and surrounding entities Common to all entities Entity Definition Constraints Specific to an entity Represent how entity was defined (during creation)

Tangency Constraints Relation between entity and surrounding entities Common to all entities Free / Fixed / Float on Previous / Float on Next Only editable in Alignments feature Not editable through the API They may affect the entire Alignment/Profile object

Definition Level Constraints Specific to an entity type Represent entity definition Indicate which parameters can be modified

Recommendations Working with Constraints Separate logical code from process Use “Strategy Pattern” for processing algorithms Evaluate constraints to decide strategy

Strategy Pattern Let’s Look at some code Behavior defines interface Context provide point for customization Concrete implementations of interface Decide who customizes behavior Let’s Look at some code

Summary Alignment and Profiles Linear objects composed by entities Different interfaces to access entities Provide your own entity abstractions (wrappers) Implement process as Functors (Function Objects) Separate logical code from processing code Centralize logic (Decision methods / Factory methods) Provide customization of behavior (Strategy Pattern)

Questions?

C3D API Challenge Reinforce the topics of this class Have fun with them Featured in Civilized Development Details in materials handout Submit entries prior December 31st 2011

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