1.0 Overview 

2.0 Using the HOOPS 3D Part Viewer for ACIS

• 2.1 Opening/Reading Files
• 2.2 Command Line Arguments
• 2.3 Modifying Application Settings
• 2.4 Saving Files
• 2.5 Creating HTML Pages
• 2.6 Copying to Clipboard
• 2.7 Printing / Print Preview
• 2.8 Camera Manipulation
• 2.9 Entity Selection
• 2.10 Querying the Model
• 2.11 Measuring Distance
• 2.12 Setting Visibility of Lights
• 2.13 Setting Visibility Of ACIS Entities
• 2.14 Setting Selectability Of ACIS Entities
• 2.15 Changing the Render Model
• 2.16 Changing the Viewing Projection
• 2.17 Topology Browser
• 2.18 Frame Rate Options
• 2.19 Shadow Display
• 2.20 Axis Triad

3.0 Material Editor

4.0 InterOp Integration

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1.0 Overview

The HOOPS 3D Part Viewer for ACIS is available for the MS Windows platform and is built using the ACIS Kernel Modeler and the HOOPS 3D Application Framework. By licensing these components, developers can easily customize or extend this application or port it to the major UNIX platforms, including Linux. Web-based applications may also be created using HOOPS/ActiveX extensions, HOOPS/Netscape extensions, or the HOOPS JNI bindings. In addition, developers may license additional modules for the reading and writing of the STEP, IGES, VDA-FS. CATIA, Pro/E and X_T file formats. 

The underlying architecture of this part viewer consists of the HOOPS 3D Product Suite from TSA, including it's tight integration with the ACIS Modeling Kernel from Spatial. The HOOPS and ACIS components are modular and extensible tools which help developers rapidly deliver world class 2D/3D applications.

The Part Viewer includes the following functionality:

• Read and Save SAT files.
• Read and Save ASF (Acis Stream File) files.
• Read HSF (HOOPS Stream Format) files as well as VRML, STL and OBJ (Alias|Wavefront) formats.
• Web publish any loaded files via the "Save As HTML" and "Save as HSF" capabilities. HSF is the HOOPS Stream Format at the center of the OpenHSF Initiative.
• Navigate even the most complex parts in real time by turning on the constant frame rate manipulators.
• Save SAT files as AcisHOOPS Stream Files (ASFs) for faster file loading and visualization. ASFs contain both the original CAD geometry and its corresponding faceted representation. Storing the faceted data with the model means that the model does not need to be re-tessellated when read in, which results in significantly faster load times.
• Save files as Windows EMF and tiff image formats.
• Query the ACIS model and do distance calculations.
• Browse the topological hierarchy of the ACIS part file.
• Create selection sets of ACIS entities. 
• Switch between Render Modes (Shaded, Triangulated, Wireframe, Hidden Line). 
• Visualization operations such as Orbit, Pan, Zoom, etc.
• Markup capabilities such as freehand, circular, text.
• Move entities within the scene using the high-speed HOOPS "Spriting" algorithm. 
• Print, Print Preview and Copy to Clipboard. 
• Real-time, simultaneous collaboration between multiple users.
• On-demand and view-dependent HSF file streaming from HOOPS/Net server.
• Playback of HSF animation

In addition to its use for viewing ACIS models, saving to other ACIS versions, web-publishing your SAT files and allowing users to collaborate in real-time, this application is intended as a demonstration of the power of the HOOPS 3D Product Suite and ACIS Kernel. As such, it serves as a reference architecture from which developers may extend and build their own CAD/CAM/CAE applications.  For more information about licensing the framework to build custom CAD/CAM/CAE application please contact either info@techsoft3d.com.

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2.0 Using the HOOPS 3D Part Viewer for ACIS

The HOOPS 3D Part Viewer for ACIS has been designed to work and act like any standard Windows application.  It uses the MFC multi-document interface (MDI), supporting the standard MFC services (New, Open, Save As, Print, Print Preview, Copy to Clipboard). ACIS SAT files may be read, interrogated, viewed and saved.

• he Viewer has the concept of an active render mode and an active model operator. The render modes (Wireframe, Triangulated, Gouraud Shaded, Hidden Line) can be toggled by using the "right click" menu. 
• The model operators can be selected to invoke camera manipulation (Orbit, Pan, Zoom, Zoom to Window, Zoom to Extents, Set View Plane) or the selection operators (Select by Single Click, Select by Window).  The operators can be made active by clicking on the appropriate icon or pull down menu.

There are various toolbars available. These can be hidden/shown through View-Toolbar menu. 

Standard Toolbar:

• File New - Creates a new empty window. Files can then be loaded into the new scene via the File/Load button
• File Open - Launches the MFC file browser. Use this to find and open a ACIS Part File or HOOPS Stream File
• Copy - Copies the contents of the current (top) MDI window to the Windows clipboard 
• Print - Prints the contents of the current (top) MDI window via the Windows system printer
• Zoom to Extents - Resets the camera to view the entire scene 
• Orbit - Use the mouse to interactively orbit the camera 
• Pan - Use the mouse to interactively pan the camera in the active view 
• Zoom - Use the mouse to interactively change the camera field (Zoom in or out)
• Zoom to Window - Use the mouse to define a new camera view field 
• Zoom to Selection - Zooms to the currently selected object 
• Select By Single Click - Use the mouse to select on ACIS entities 
• Select by Window - Use the mouse to define a window to select ACIS entities
• Shaded - Sets the rendermode to Shaded
• Hiddenline - Sets the rendermode to Hiddenline
• Wireframe - Sets the rendermode to Wireframe

Tools Toolbar:

• Annotation - Create a text annotation. After clicking on this button, click on an object in the scene to which annotation is to be attached. Move the mouse and click again and begin typing your text annotation. Press 'Enter' to complete. You can also click on the annotation and drag it to relocate it.
• Measure Distance - Interactively query the distance between two points on the Model.
• Create Cutting Plane - Creates a cutting plane and inserts it in the scene. Clicking again removes the cutting plane. Holding Down [SHIFT] while clicking on th button while the cutting plane is active removes the handles from the plane. Use the mouse to interactively rotate/pan the cutting plane to see the sections of models in various planes.  
• Query Model- Interactively query the geometry and topology in the scene. 
• Test Performance - Animates the model in the scene to test the performance. Displays the information about the performance (in frames/second) achieved. 

Markup-Text Toolbar:

• Freehand Markup - Use this tool to draw free-hand markups in the scene. Click the left mouse button and drag.
• Rectangle Markup - Use this tool to draw rectangular markups in the scene. Click the left mouse button and drag.
• Circle Markup - Use this tool to draw circular markups in the scene. Click the left mouse button and drag.
• Text Markup - Use this tool to insert text markups in the scene.
• Save/Restore Markup 1,2 -Pressing any of these buttons for the first time the application will store the markup data and current camera position and associate it to that button. Clicking on the button at any later time in your session will cause the application to re-position your view at the saved camera position with the markup data restored. To erase a saved camera position hold down the [SHIFT] key while clicking on the button.

Standard Views Toolbar:

• Front - Sets the camera in the active view to the front of the object. 
• Back - Sets the camera in the active view to the back of the object. 
• Top - Sets the camera in the active view to the top of the object. 
• Bottom - Sets the camera in the active view to the bottom of the object. 
• Right - Sets the camera in the active view to the right of the object. 
• Left - Sets the camera in the active view to the left of the object. 
• Isometric - Sets the camera in the active view to show the object in isometric position. 

There are also a number of settings that can be toggled by clicking on the right mouse button.  They are:

• Selection Level - Allows user to toggle the topological selection level on the active view, including selectability of vertices, edges, faces and bodies. 
• Visibility - Allows user to toggle on/off the visibility of different ACIS topological entities including vertices, edges and faces, as well as the visibility of lights in the scene. 
• Render Mode - Allows user to switch between different visualization modes, including triangulated (flat shaded), wireframe, Gouraud shaded, or hidden-lines removed.

The full set of features are explained in more detail below:
 

2.1 Opening/Reading Files

The Part Viewer reads SAT, HSF, STL, VRML and HMF files. For your convenience, a set of demonstration files are contained on this media located in the parts directory of your installation. The files are of varying degrees of complexity so certain files may take a couple of seconds to load depending on the speed of your system.

2.2 Command Line Arguments

In certain cases it may be preferable to start the Part Viewer from the command line. To do this, specify the files which you want loaded. For example,

> acispartviewer.exe bnc.sat  

2.3 Modifying Application Settings

The application settings are the options which are applicable to all the documents in the application. These are stored in the registry and are restored back when the application is launched again. You can modify these settings by clicking on Tools-Options menu.

General Settings

• Display
  • Driver: Sets the HOOPS display driver. 
  • Disable Hardware Acceleration: Sets HOOPS to use software rendering. Only works for the OpenGL and Direct3D drivers.
  • Axis Triad: If checked, displays X-Y-Z axis triad at the left-bottom corner of each document.
  • Shadow Rendering: Sets the Shadow Rendering Mode. Can be used to work around hardware problems with shadow rendering.
• Camera
  • Smooth Transition: If checked, the camera is transitioned between two positions smoothly (in small increments).
  • Projection: Sets the camera projection.
• Rendering
  • Shadows: If checked, shadows will be generated.
  • Display Lists: If checked, display lists will be used. Usage of display lists can increase the performance upto 5 times. This option is only valid if you have OpenGL driver set.
  • Occlusion Culling: If checked Occlusion Culling will be performed on the current scene which can result in significant performance gains with some models. This option currently only has effect when the OpenGL driver is selected and certain hardware requirements are met.
  • Framerate enabled on Startup: If checked Constant Framerate Logic will be activated when a new model is loaded
  • Fast HLR: If checked HOOPS will never use the precise, analytical Hidden Line mode.
  • Culling Threshold: If checked will set the pixel culling threshold for occlusion culling.
• Geometry Manipulation
  • Update Shadows: If checked shadows will be updated during translation/rotation of objects.
  • Use 3D Spriting: If checked spriting is used during translation/rotation of objects
• Transparency
  • Style: Allows you to set the style of transparency.
  • Sorting: Allows you to set the sorting algorithm used for transparency.
  • Layers: Allows you to set the number of layers for the depth peeling transparency sorting algorithm.
• Antialiasing
  • Use Anti-aliasing: If checked, enables scene anti-aliasing, with the option to set the anti-aliasing quality (number of samples).
  • Text: If checked, enables text anti-aliasing.
  • Lines + Edges: If checked, enables anti-aliasing for only lines and edges. In practice, this setting is redundant if screen anti-aliasing is already enabled.
• Apply: Pressing this button will Apply the current settings to the associated view.
• Reset: Pressing this button will restore the settings to factory default.

Appearance Settings

• Line/Edge Geometry
  • Default Line/Edge Weight: Sets the default line/edge weight.
• Background Color
  • Top: Sets the background color for the upper portion of the window. The background color can have a gradient from top to bottom.
  • Bottom: Sets the background color for the lower portion of the window. If you prefer a single background color without any gradient, set this color exactly same as the Top Background Color.
• Color Interpolation
  • Color Interpolation: If checked, honors the color settings at each vertex of the Shells in the scene and applies a color ramp across the shell.
    • By Value: Controls the color interpolation scheme for Shells which have vertex level coloring. If checked, the color at eachpixel in the face is determined by simply linearly interpolating the RGB color set on the adjacent vertices.
    • By Colormap: Controls the color interpolation scheme for Shells which have vertex level coloring. If checked, the color at each pixel by is determined by interpolating between the indices in the colormap. This option is only valid if the Shell vertex colors have been set by Index.
      • Isolines: If checked, renders only the Isolines for Shells in the scene which have colors set on their vertices.
• Markup
  • Color: Sets the color of Markup lines. 
  • Weight: Sets the line weight (thickness) for the Markup.
• Shadow
  • Color: Sets the color of the Shadow.
  • Res: Sets the shadow resolution (values between 32 and 256 are allowed)
  • Blur: Sets the amount of shadow blurring (values between 1 and 64 are allowed)
• Fonts
  • Name: Sets the current font for the scene.
  • Size: Sets the current font size in points.
  • Scalable: If checked annotation will scale as the camera position changes.
• Apply: Pressing this button will Apply the current settings to the associated view.
• Reset: Pressing this button will restore the settings to factory default.
   

File Settings

• HOOPS Stream File Export Options
  • Compress Vertices: Compresses the vertices of entities which reduces HSF file size, but can sometimes result in visual artifacts. 
  • Bits per Vertex: Number of bits to be used for storing each vertex. This can be any integer between 8 & 72. This is applicable only if Compress Vertices is chosen. 
  • Compress Normals: Compresses the normals  of entities which reduces HSF file size, but can sometimes result in visual artifacts. 
  • Bits per Normal: Number of bits to be used for storing each normal. This can be any integer between 8 & 72. This is applicable only if Compress Normals is chosen.  
  • HSF Version: The export version number for HSF files. 
  • Include File Dictionary: Export the file dictionary information. File Dictionary provides random entity access capability, but usually results in marginal increase in the size. 
  • Use Advanced Compression: Export the HSF file using the advanced edge-breaker connectivity compression. For more details on this type of compression, please refer to the HOOPS/Stream documentation. 
  • Include Line/Edge Data: Exports non-surface data to the HSF file, such as lines, arcs, text, circles, etc...  It is useful to export this data if either:
  • A.  the data originated as an SAT file and accurate wireframe or hidden-line renderings are desired
  • B.  much of the interesting geometry in the file is 'line data'; this would of course be the case if the model was an AEC-type model such as a 2D floorplan. 
  • Include Topology Information:  If selected, HSFs will contain the associativity information between the graphical entities and their assembly structure. This can then be used to navigate the topological structure of the model without the need for the modeling kernel or the SAT file. Since this information is stored within the file it does increase the file size, which may be undesirable if you are streaming the files across bandwidth constrained networks. 
• ACIS (.SAT) File Settings
  • Export Version Number: The export version number for ACIS files.
  • Location of Part files: The directory location of the SAT files.
• Reset: Pressing this button will restore the settings to factory default.  

Interaction

• Walk Options
  • Use Keyboard: Checking this enables keyboard controls for movement. Keyboard controls are as follows:
    • W: Forward
    • A: Strafe Left
    • S: Back
    • D: Strafe Right
    • Q: Up
    • Z: Down
  • Collision Detection: This enables collision detection between the camera and geometry in the scene.
  • Snap to Floor: If checked, the walk operator will prevent the camera from floating too high over a surface, and snap to the floor when possible.
  • Avatar Height: This controls the height of the camera when the camera is snapped to the floor.
    • Automatic: Allows HOOPS to automatically set the avatar height to be a fraction of the scene extents.
  • Step Height Up: This set the height at which the avatar will automatically walk up stairs and over small obstacles.
  • Step Height Down: This sets the maximum height that the avatar can drop. Thus, if the drop is too large, the avatar will not be able to walk over an edge.
• Animation
  • Show Every Tick: If checked displays every tick of the animation regardless of the time per frame.
  • Update Camera: If not checked camera movement which is part of the animation will be surpressed
  • Jump To Keyframe: If  checked the +/- button of the animation toolbar will move the animation to the next keyframe instead of the next tick
  • Disable Constant Framerate: If  checked the Constant Framerate Logic will be disabled while an animation is running.
  • Timer Based Update: If checked updates are happening on regular intervals which allows animations to interact smoothly with other user input. Turning this off can help in code debugging.
  • Show Collisions: If checked will enable visualization of collision detection in animations.
• Camera
  • Front View Axis: Sets what the partviewer will consider the "front view" for use with the "standard views" buttons.
  • Top View Axis: Sets what the partviewer will consider the "top view" for use with the "standard views" buttons.

Selection

• Appearance
  • Polygons: Sets the selection color for polygons (faces).
  • Lines: Sets the selection color for lines (edges).
  • Markers: Sets the selection color for markers (vertices).
  • Transparency: Sets the transparency level (%) for the selected entities.
  • Gray Scale Selection: If checked, sets the scene to grayscale when performing a selection.
• Behavior
  • Visibility based selection: If checked all selection operations take visibility of objects into account (versus the standard analytical selection mode of HOOPS)
  • Dynamic Highlighting: If checked, will automatically highlight geometry on a mouseover (and subsequently unhighlight when the mouse leaves.
  • Honor Line/Edge weight/patterns: If checked, HOOPS will honor the weights and patterns of lines and patterns.

2.4 Saving Files

The Part Viewer allows you to save models as: 

• SAT : Save file as a ACIS SAT File. You can choose the ACIS version number of the file is via the 'File Settings' button under the File menu. 
• ASF : Saving the model as an ASF file will cause the original SAT file data, the faceted information, and the associatively between the two to be stored within a single file. Since re-facetting will not need to occur when you load these files, load times will be significantly reduced.
• HSF: Saving Files as HOOPS Stream Files will create a compressed file containing the faceted data in the scene. If 'Write Topology Information' was enabled in the 'File Settings' dialog, then additional user data which specifies the topological structure of the original CAD model will be exported to the HSF file as well. Since this file format contains a compressed, tessellated 3D representation of the SAT file, load times are significantly faster than that of a standard SAT file. File sizes are also substantially smaller typically in the range of 10% - 20% the size of the original model. To ensure that Levels of Details (LODs) of objects in the scene are included in the HSF you must instruct the PartViewer to generate LODs for the scene. This is automatically done by turning on Level of Details when you set a constant framerate via the Frame Rate Options dialog in the view menu.
• HTML: Choosing the "Save as HTML" option creates an HTML page with the selected HSF embedded. These HTML pages can then be posted to a web site as live 3D data. The HTML page also has an embedded HOOPS 3D Stream Control which will stream the HSF from either a local disk or a web site. The embedded object will, behind the scenes, download and install the HOOPS 3D Control if it is not already installed on the machine reading the web page. This means that developers simply need to put the HTML and HSF file on their Web site and any user of MSIE can view the model over the web by simply pointing their browser to the page's URL.
• EMF (Windows Encapsulated Metafiles) : These files can then be imported into any standard Windows application. The output is vector data when in either wireframe or hidden line mode. EMF output is used when you 'Copy to Clipboard'.
• TIFF: These image files can be used to bring any of the data into any of the standard image editing software package. 

2.5 Creating HTML Pages

HTML pages are created simply by saving the file as a HTML page. When you save a file as an HTML page two files will be created; an HTML file which references a newly created HSF file with the exact same filename. (So, SaveAs-> 'foo.html' would create two files: foo.html and foo.hsf.) To publish your model to the web simply copy both these files to your web site. The HTML page uses the HOOPS 3D Stream Control which, if not already installed the user's system, will be automatically downloaded and installed when the HTML page is viewed. By default, the PartViewer does not include Levels of Detail (LODs) in the HSF. Since LODs are ordered in the front of the file and are much smaller than the original objects they represent it is very beneficial to have LODs in the HSF to facilitate streaming. LODs may be generated through the Frame Rate Options in the View pulldown menu.

2.6 Copying to Clipboard

As is standard with Windows Applications, Ctrl-C will copy the contents of the screen to the clipboard (in the form of an EMF). You can then easily import  the metafile into any of the usual windows applications such as Microsoft Word, Excel, Power Point, etc.

2.7 Printing/Print Preview

The application supports standard Windows GDI Printing and Print Preview.  Although not currently in this version of the application, HOOPS/3dGS supports HPGL, Postscript and CGM output. Developers wishing to extend this viewer to contain such functionality may easily expose it by licensing the HOOPS 3D Application Framework. 

2.6 Camera Manipulation

Each MFC window has a separate HOOPS camera that may be manipulated to change the current view of the model. The camera operations implemented are: 

• Orbit
• Pan
• Zoom

These are modal Operators on the View and are chosen by toggling the appropriate menu button or by using the pull down menus on the frame. Once a camera manipulation operator has been selected, the camera may be interactively manipulated with the mouse. All operators respond to the following sequence: left mouse button down, left mouse button down & moved (motion), left mouse button up. 

Starting with this release the functionality of the Orbit Operator has been extended to allow for panning and zooming without switching operators. Holding down the [SHIFT] key while dragging the mouse will initiate a camera pan while holding down the [CTRL] key will zoom the camera. In addition holding down the middle (or third) mouse button while over an object will orbit the camera around the selected point.

At any time double clicking the middle mouse button will either zoom to the object under the cursor or (if no object is under the cursor) will reset the camera to the scene extents.

Smooth Transition

This feature can be toggled on or off via the Manipulate pull down menu. When turned on the camera will be smoothly transitioned (producing animation effect) when user zooms to window, changes the view plain or resets the camera.  

2.9 Entity Selection

There are three primary ways of selecting entities in the ACIS model:

• Select by Single Click

  Select by Single Click is the default pick mode.  Selections highlight the ACIS entity type that is nearest to the Windows mouse click. 

• Select by Window

  Select by Window selects and highlights all the specified ACIS entity types under the window defined. The window is defined by a sequence of events using the left mouse button: down, down and motion, up. 

• Selecting via the Topology Browser Entities may also be selected via the topology browser. Clicking on the entity in the browser will automatically highlighted the corresponding graphical entity in the scene. Clicking the 'Zoom to Selection' checkbox in the browser dialog will cause the camera to be automatically positioned in front of the highlighted entity.

Selection lists containing multiple entities may be created by holding down either the Shift or Ctrl key while using either of the Selection Operators and can be used to build up selection lists for the topology browser. 

The Part Viewer makes use of the MFC "right click" user interface to provide a mechanism for controlling the visibility and selectability of entities in the scene. Positioning the mouse in the view window and pressing the right mouse button invokes a floating menu bar. The behavior of the selection operators can be configured via this floating menu bar interface. The interface may be used to determine which ACIS Topological Entity type is selectable. Selections can be made on the nearest ACIS: Vertex, Edge, Face, or Body.   The color of the selected geometry is changed to white (or "highlighted"). 

To ensure optimal rendering performance, face selection is disabled by default. Face selection can be enabled from this menu, however note that this will cause the object to be re-tesselated which can take time depending on the size of the model.

2.10 Querying the Model 

The query operator allows users to query information about the ACIS part and is selected by toggling the appropriate menu bar button. Once selected, the mouse may be used to interactively query ACIS Models. The first time the left mouse button is pressed while in the view and over an ACIS model an MFC dialog window is created and displays the following information: 

• Analytical intersection of the selection ray with the ACIS geometry
• ACIS Entity Body Pointer entity queried
• Number of Edges and Faces in the Body queried

Moving the mouse around the scene with the left button depressed will cause this information to be updated in real-time.  

2.11 Measuring Distance

Users can query and measure the distance between two points in the scene. When this operator is selected,  a dialog similar to the Query dialog will appear. In addition to displaying the standard query information the distance between two points will be displayed. A left mouse button click will select the beginning point of the measurement. Measurement is shown by holding the left button down and dragging to the desired end point of the measurement. A line will be shown between the two points. 

2.12 Setting Visibility of Lights 

The application makes use of the MFC "right click" user interface to provide a mechanism for controlling the visibility and selectability of the entities in the scene. Positioning the mouse in the view window and pressing the right mouse button invokes a floating menu bar. Lights may be toggled off or on in the Visibility. Turning Lights off will cause the model to appear "flat" or non-shaded.

2.13 Setting Visibility of ACIS Entities

Via the same right click floating menu bar, the user can turn the visibility of ACIS Vertices, Edges or Faces off or on.

2.14 Setting Selectability of ACIS Entities

The Selectability of ACIS entities are also be controlled via the right click button.  By moving to "Selection Level" you can enable or disable the selection of ACIS Vertices, Edges, Faces or Bodies. Note that selection of faces is turned off by default for rendering optimization.  If Face level selection is enabled, the model will be need to be re-tesselated. To highlight a face in the scene without requiring a re-tesselation, simply click the "Show Face Outlines" button.

2.15 Changing the Render Mode

Render Modes for the scene are also controlled via the right click mouse button.  There are 4 different rendering modes provided for viewing models.

• Wireframe
• Triangulated (allows you to see the facetting of the model) 
• Gouraud (Smooth) Shaded 
• Hidden Line 

Upon startup, the default rendering mode is Smooth Shaded. Please note that the Hidden Line algorithm is computationally intensive and for large models may take several seconds.  Visibility of the hidden lines is controlled by the right click Visibility menu. 

2.16 Changing the Viewing Projection

By default, the scene is rendered with a Perspective viewing projection, you can change this to an Orthographic viewing projection via the View menu.  

2.17 Topology Browser

Selecting the Topology Browser from the Query Menu allows you to browse the topological structure of the model. As you select on entities in the dialog they are highlighted in the visualization window and any user-defined attributes are displayed in the Topology browser's text box. To ensure optimal rendering performance, face selection is disabled by default. Turning on face selection can be enabled from this menu, however this will cause the object to be re-tesselated which can take time depending on the size of the model.

2.18 Frame Rate Options

From the "View" pulldown menu, users may define a desired framerate to be maintained during rendering. When setting this option you can ask the application to 'Use Levels of Detail' in order to maintain the requested framerate.  This causes HOOPS to generate simplification levels for each body. The default values may be used, or the user may control the number of levels which are generated and the percentage fall-off between levels. 

The 'LOD Settings' tab provides control over the LOD generation process. 'Detail Levels' allows the user to control how many Levels of Detail should be generated. The Falloff Value represents what percentage of vertices the new LOD should contain as compared to the next highest level. For example, a falloff value of 0.30 would mean that the Level 1 LOD would have 30% of the vertices of the original object. If desired you can see the individual LOD levels directly via the 'LOD Level' item in the 'View' menu pulldown.

If the system can't maintain the user specified frame rate HOOPS will drop through the different simplification levels in order to keep up with the desired frame rate. Generating levels of detail has an associated one time pre-process cost which can be significant depending on the size of the model.

Turning on the Threshold LOD type will cause the application to utilize further HOOPS/3dGS logic to determine the LOD level on each body separately, depending on its triangle count per square window space unit.

You can also tell the viewer to simplify to allow one of the LODs to be simply the bounding box of the object. Depending on the model these may or may not be desirable.

2.19 Shadow Display

Display of Shadow for the objects in scene can be toggled using "Shadow" option from "View" menu. Shadow is displayed on the plane perpendicular to the current view-up vector. 

2.20 Axis Triad

Beyond indicating the current orientation of the camera the axis triad can be used to access the Orbit/Pan/Zoom functionality (as described in 2.6) by clicking and dragging the mouse pointer in the axis window. Also clicking at any of the arcs indicating a particular view plane the camera will automatically realign the view to that plane.

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3.0 Material Editor

The Material Editor makes it easy to create a library of Material "Styles" based on colors, textures and visibility settings and apply them to geometry in the scene.

The left side of the dialog contains the style preview window as well as a horizontal list of styles which allows the user to select among the various styles and apply them to the current selection. There are also options for creating a new style, deleting, renaming or cloning the current style. A set of styles can be saved out to an hsf file or loaded back into the current model.

The right side of the dialog contains the texture, color and visibility settings for the selected style and allows the user to manipulate the texture parameters (which are global to all styles). In the "Texture Settings" window a new image can be loaded which will automatically be associated to a texture. Various texture parameters are exposed and can be changed (please refer to the HOOPS 3DGS Reference Manual for more information on textures in HOOPS). Additionally individual images or textures can be deleted and existing textures can be cloned.

The "Style Settings" on the right side expose the various color components of a particular style grouped by entity type. Textures can be applied to the various face color components and the visibility for the entity types can be changed. All those changes are imediatly reflected in the preview window as well as all geometry to which the selected style has been applied.

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4.0 InterOp Integration

If you have InterOp installed, you can run a version of the HOOPS/InterOp ACIS Part Viewer which can be built using the acispartviewer_interop_vc<MS Visual Studio Version>.vcproj project found in <hoops>/demo/mfc/acispartviewer directory.

The ACIS/InterOp Part Viewer has all of the same capabilities as the ACIS Part Viewer with the addition of several other features. It can read and write the CAD file formats supported by InterOp.

While in the Part Viewer, users can launch the InterOp Part Browser from Tools menu. This browser shows the Part Info Window and the Browser Window. In the Part Info Window, users can see the BREP content of the document including number of bodies, edges, faces and other metrics. Users can also examine the E-BOM XML description of the assembly in the Browser Window. This includes an entry for each part of the model with a link to the log file that was generated during translation.

Figure 4a: The ACIS/InterOp Part Viewer with the InterOp Part Browser opened.