CAD – Physics Based Modeler
Document Type: Software Requirements Document
CAD Physics Based Modeler
Software Requirements Document
V 1.2
Physics Based
Modeler
Charlie Darney
Shaw Levin
John Connor
Alex Kates
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
Table of Contents
Table of Contents .......................................................................................................................................... 2
1 Introduction............................................................................................................................................. 3
2 Glossary ................................................................................................................................................. 3
3 Overview ................................................................................................................................................ 3
4 Background ............................................................................................................................................ 3
5 Functional Requirements ........................................................................................................................ 6
5.1 General ................................................................................................................................................ 6
5.2 User Interface....................................................................................................................................... 7
6 Non-Functional Requirements................................................................................................................. 9
6.1 Usability ............................................................................................................................................... 9
6.2 Reliability............................................................................................................................................ 10
6.3 Performance....................................................................................................................................... 10
6.4 Supportability ..................................................................................................................................... 11
6.5 Ease of Configuration ......................................................................................................................... 11
6.6 Implementation Constraints ................................................................................................................ 11
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
1
Introduction
The purpose of this document is to explain in specific detail the CAD Physics Based Modeler
project. It explains the functional and non-functional behaviors of the software, not the specific
implementation and development of the software.
2 Glossary
CAD – Computer Aided Design.
CAGD – Computer Aided Geometric Design.
TCO – Temporal Computational Object.
PBM – Physics Based Modeler.
VX CAD – Computer Aided Design software used as platform for physics based modeller
utility.
3
Overview
The CAD-PBM utility is a Graphical User Interface that bridges the gap between the VX
CAD design application and the physics-based modeler (PBM). This system will allow for users to
seamlessly create objects in the VX CAD system and iteratively add a surface to them using the
PBM system without the need to repeatedly input object information into the PBM application. The
application will reduce the time necessary to add surfaces to CAD objects and allow for
modifications through both a menu and GUI system. It will accomplish this by saving a file from VX
CAD, sending it to the PBM and then returning a file that has been edited by the PBM back into VX
CAD format for further inspection and editing.
4 Background
The physics-based modeling approach generates high quality surfaces for application in
CAGD. Physics-based modeling is commonly used in animation and scientific modeling, and
simulates realistic dynamic motion for computer graphics. The proposed physics-based modeling of
liquid surface motion is a means to generate complex geometry. Regions of a model are defined to
be in a solid phase and other parts are in a liquid phase. The liquid surface is mobile and moves in
response to physics-based forces resulting in a smooth, minimum energy surface. The objects
created by this method are referred to as Temporal Computational Objects (TCO’s).
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
TCO’s are created in context in CAD. The angle geometry is downloaded from a website in
a VX CAD format. The model boundaries are generated using basic CAD functionality as shown in
Figure 1, available in the VX CAD application. The objective is to take a common part and
transform it to a TCO with the same basic functionality. The geometries of interest are the mating
surfaces of the part. Those surfaces will remain the same. All the other part surfaces will be
transformed into a TCO format.
Figure 1: Model Boundaries for a TCO Provide the Initial Conditions for Generation.
The boundary elements are generated by segregation of parts of the original wireframe. The
segregation creates separate datasets that are then operable in a TCO environment. The principal
need for segregation is to identify the fixed boundaries of the object. Otherwise the form would
reduce to a sphere during generation. The upper and lower surfaces will be predominately contoured
whereas the mating surfaces with be predominately flat. The geometry elements are comprised of
arc and line segments that form closed loops as shown in Figure 2. These closed loops define the
surface patch.
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
Figure 2: Wire Frame Geometry is Converted to a Series of Closed Loops that is Compatible with TCO
Generation. Here, the Figure on the Left is Comprised of Line Geometry Which is Converted to Loops on the
Right in Dark Blue.
The current process takes the base CAD geometry and adds information about that geometry
to enable the generation of a quasi-static liquid surface. The initial .fe file is a Sparse Initial
Boundary Conditions (SIBC). The file includes the geometry specifications from CAD, extrinsic
parameters and environmental parameters such as gravity, scalar fields, vector fields, etc., and
intrinsic parameters such as surface tension, body number (associated with a group of facets), body
volume, fixed/free facets, etc.
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
5 Functional Requirements
5.1 General
5.1.1 The module shall load at the same time as VX CAD.
5.1.2 The module shall close at the same time as VX CAD.
5.1.3 The module will initially load a user interface and canvas.
5.1.4 The user shall be enabled to define TCO boundary conditions using
VX CAD.
5.1.4.1 The user shall be able to define single or multiple boundary curves.
5.1.4.2 The user shall be able to define multiple closed loops.
5.1.4.3 The user shall be able to define scalar fields.
5.1.4.4 The user shall be able to define fixed boundaries or free boundaries.
5.1.4.5 The user will be able to segregate surfaces.
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
5.1.4.6 The user shall be enabled to define TCO evolution specifications.
5.1.4.7 The user shall be able to define extrinsic parameters.
5.1.4.7.1 These parameters include volume, area, energy, tension, etc.
5.1.4.8 The user shall be able to define intrinsic parameters.
5.1.4.9 The user shall be able to define the TCO generation process.
5.1.4.10 The user shall be enabled to repeatedly evolve a TCO based on its
boundary conditions and evolution specifications.
5.2 User Interface
5.2.1 The exposed functionality of the module shall be accessible through a
toolbar.
5.2.2 The TCO operations shall be viewed from the canvas.
5.2.3 The TCO operations include all parameter specifications.
5.2.4 The TCO operations include all TCO generation features.
5.2.5 The toolbar shall be accessible from the main interface of VX CAD.
5.2.6 The toolbar shall consist of the following functionality:
5.2.6.1 New
5.2.6.1.1 Opens evolution toolbar and creates blank canvas.
5.2.6.2 Create a blank canvas
5.2.6.2.1 Creates new blank canvas. If current open canvas is not blank,
the user will be prompted to save.
5.2.6.3 Start
5.2.6.3.1 Starts the TCO evolution process.
5.2.6.3.2 The evolution process shall use the specifications and
generation procedure defined in the canvas.
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
5.2.6.4 Stop
5.2.6.4.1 Stops the TCO evolution process at any time.
5.2.6.5 Rewind
5.2.6.5.1 Devolve the TCO.
5.2.6.6 Export
5.2.6.6.1 Save the TCO in its current state in any of the following
formats: are STL, CAD/IGS, Point Cloud, and Tetmesh.
5.2.6.7 Restore
5.2.6.7.1 Return the evolved object to VX CAD's normal canvas.
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
5.2.7 Canvas
5.2.7.1 The Canvas shall contain a specification tool frame.
5.2.7.2 The user shall enter evolution specifications into the specification
frame.
5.2.7.3 The user shall be able to specify extrinsic and intrinsic parameters.
5.2.7.4 The user shall be able to specify the generation procedure in the
specification frame.
5.2.7.5 Pressing the start button shall make use of these specifications and
the generation procedure.
5.2.8 Middleware
5.2.8.1 The module shall integrate with the 2009 version of VX CAD
Designer.
5.2.8.2 The module shall be accessed by a custom button added to the VX
CAD toolbar.
5.2.8.3 The module shall make use of the functionality provided by Surface
Evolver.
6 Non-Functional Requirements
6.1 Usability
6.1.1 Speed of Use
6.1.1.1 The system shall complete standard TCO modelling in under
fifteen (15) minutes.
6.1.2 Required User Ability
6.1.2.1 The system shall require the user have at least intermediate
experience with CAD software.
6.1.2.1.1 The system shall require the user have knowledge of TCO
design.
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
6.1.3 Documentation
6.1.3.1 The system shall have documentation for both VX CAD and PBM.
6.1.4 On-line Help
6.1.4.1 The system shall have all documentation accessible online.
6.2 Reliability
6.2.1 Error Handling
6.2.1.1 The system shall alert the user of errors consistent with VX CAD
error handling.
6.2.1.2 The system shall save the current TCO configuration in the event of
a system malfunction.
6.2.2 Ease of Recovery
6.2.2.1 The system shall restore the TCO configuration after system
malfunction.
6.3 Performance
6.3.1 Response Time
6.3.1.1 The system shall perform surface changes in iterations such that the
user may visually confirm changes in process.
6.3.2 Resource Usage
6.3.2.1 The system shall be restricted by PBM from the capacity of the
system’s memory
6.3.3 Degradation Under Overload Conditions
6.3.3.1 The system shall alert the user of expected generation requirement
regardless of size.
6.3.3.2 The system shall cause overloads with extended calculation or hang
time.
6.3.3.3 The system shall not overload VX CAD by staying within the
operation limits of this software.
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CAD – Physics Based Modeler
Document Type: Software Requirements Document
6.4 Supportability
6.4.1 Ease of Installation
6.4.1.1 The system shall require the installation of both VX CAD and PBM.
6.4.2 Planned Maintenance
6.4.2.1 The system shall allow for additional VX CAD tools to be added
depending on completing of minimum requirements.
6.5 Ease of Configuration
6.5.1 The system shall allow for configuration of TCO objects in text form.
6.6 Implementation Constraints
6.6.1 Language
6.6.1.1 The system shall be written in C/C++.
6.6.2 Operating System
6.6.2.1 The system shall operate in all the Windows versions supported by
VX CAD.
6.6.3 System Interfacing
6.6.3.1 The user shall interface with PBM via the standard VX CAD
interface.
6.6.4 Screen Resolution
6.6.4.1 The system shall run with a minimum video resolution of 1024x768
with at least 65536 colors.
6.6.4.2 The system shall have a recommended resolution of 1280x1024.
6.6.4.3 The system shall require user configuration of VX CAD while
running on the minimum resolution.
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