Vega prime  

101  Why do my Models Load So Slowly in Vega Prime 2.0  

Some users have seen some major issues with loading files models that loaded fine in Vega Prime 1.2x but take for every to load or do not load at into Vega Prime 2.0, this seems to affect OpenFlight and VSB files alike

The way files are loaded was changed extensively for Vega Prime 2.0, with many  more option and optimization possibilities added ( these are actually very good changes, but the changes seem to have broken Lynx prime quite badly).

It appear that if you try to load models listed in a Vega Prime 1.2 ACF file then you more likely to see the slow or no load problems.

The solution for some is to create a new ACF from scratch using the Vega Prime 2.0 Lynx Prime.

Alternatively load your models through code, you might want to check the code you use by saving a default ACF to a CPP file and check the vpObject settings

This is a frustrating and needless Bug and should have been highlighted in the release notes etc ...

 

102  Where did the Compatibility Mode go in Vega Prime 2.0  

 

Where did the Compatibility Mode go that was in Vega Prime 1.x and Lynx Prime 1.x  I cannot find it in Lynx Prime 2.0

The compatibility mode have been retired, and yes this is a good thing.

The compatibility mode was an attempt to help uses transition to Vega Prime from performer and Vega Classic were the OpenFlight loader and Vega applied default materials and colours to objects. Thus allowed users to user there models in Vega Prime with out having to correct material and colour issues.

Sadly compatibility mode just confused many people and was maybe was a little ill conceived or implemented and really should never have seen the light of day

And now its gone but on the upside Vega Prime and Lynx Prime 2.0 have introduce lots of new features and many are on an Advance Tab,  there's lots of new properties to tweak and try out on the vpObject's Panel

Don't be sad it really is a good thing that is has gone....

 

103  Should I Compress My Textures    

 

A common question these days is should I be compressing or  not compressing my texture ?

One thing it depends on your platform  that your  models and textures are going to be used on.

For instance, compressing on a PC based graphics system (Windows or Linux) is in most case the best way to go because  textures that have been compressed are much smaller and faster to use.  unfortunately you cannot compress textures on SGI hardware as SGI does not at present have support for compressed textures

So on a system that  supports compression the yes use it.

Note some graphic system while supporting the use of compressed textures do no off the ability to compress a texture.

You can use the to_vsb and to_dds tools supplied with Vega prime 2.0 to convert and compress your textures

 

104  Should I Inline textures in my VSB Files  

 

That decision to inline textures really depends on your content and how your content management philosophy.

If you decide to inline your textures in your VSB files, then, on the pro side, you do not have to worry about individual texture files, paths, attributes etc anymore.

There's a but, however, the VSB file size will bloat considerably .  And is you choose not  inline, then you open up a door for texture reuse across models. while in-lining will not share resources so you may get duplication, but can help for demos and protecting IP of textures etc.

Note Vega Prime currently on supports in-lining in VSB files.

You can create your in-lined VSB thru code or to_vsb

 

105  Should I Regenerate Normals when Loading Files  

 

This depends on your models you are using.

The "Regenerate normals" loader option will trashes any  old normals and generates new ones and generate normals where missing.

The option has "normal tolerance" variable that is basically a dot-product that is used to set the maximum "crease angle" between two faces that can potentially share a normal at a mutual vertex. This basically controls how "sharp" the edges should be, and thus you can change this variable to get better visual results.

Typically though you will normally (no pun intended), create you normals and set your shading using fine control in your modeling package such as in MultiGen-Creator. So you really would not normally have to use this option, as it will increase the load time and you don't have fine control as you would in your modeling package

But if you have models that have no normals or are bad and or you cannot edit the models then you use this option to give you some acceptable if not perfect normals

 

106   Does Vega Prime Support VRML files

Currently Vega Prime does not support the reading or loading of VRML or Inventor files.

At this time I do not believe there are any plans to support the format in the near future.

Stock answer from certain people will be that you can simply write your own loader, while true this is not practical course of action for most users.

The so the only other practical option would be to use a format converter such as Polytrans or Deep Exploration.

 

107  What Model Formats does Vega Prime Support 

Unfortunately Vega Prime only supports 2 model formats directly:

*.flt OpenFlight ( MultiGen-Creator format files )

*.vsb Vega Scenegraph Binary ( Vega Primes proprietary binary format )

Any other formats need to be converted to the OpenFlight using a format converter such as Polytrans or Deep Exploration.

 

108   How Can I Convert my Models to Vega Prime Format

This would depend on what format your source models are in.

Typically you should  be able to use a format conversion program such as Polytrans or Deep Exploration. These offer a good selection of import formats and the ability to output OpenFlight models.
 

109   I Get Errors When Closing my Vega Prime Application

 

If you get errors when closing your Vega Prime application such as or similar:

"vrwindow::destroy GL Context:current thread is NOT a DRAW thread"

This is normally an indication you did not shutdown Vega correctly before you application finished and exited

Typically you must first shut Vega prime down before your application exits and you must call certain functions in the correct order .eg.

 

--

The functions must be called in the above order and from the APP thread, you cannot safely call these from any other thread such as a GUI thread etc.

 

110  Why does my Bump Isector Not Work 

 

One thing to check is that the line segments of the isector are long enough, by default Bump isector line segments are only 1 DBU in length.

Also you need to ensure you have created an Isector Service manager and associated the bump isector with the service manager. Note that you only need one service manager which you share between all isectors.

 

111   Why is the Font Size is Very Small in Lynx Prime 2.0

 

Some users including my self have found the Font Size in Lynx Prime 2.0 to be very small about 7 or points in size making things hard to read for some, but Lynx Prime 1.x is OK

It appears that a change was to the way the font size is set in Lynx Prime 2.0, the new default size does not seem to have been tested too much.

There is a work around to this, but you have to edit one of the Lynx Prime configuration files : Open the file

$(MPI_LOCATE_VEGA_PRIME)/config/VegaPrime/registry/LynXPrime.vrf

Search for a String which should read something along the lines of  "MS Shell Dlg,5.7....." or so. 

The value should be around  : "MS Shell Dlg,8.3....."

Note that the next time you re-install or update Vega Prime this file is likely to get overwritten

 

112   Does Vega Prime Support the equivalent to  VGOBJ_CLONE

 

Does Vega Prime Support the equivalent to  VGOBJ_CLONE

Vega Prime 1.x does not support an object clone method. How ever you can do this yourself quite easily by do the following 

• Create your initial vpObject  we use this as your template
• RefCount  the vpObject
• Then for each clone instance you want
• Create a vpTransform
• Add the template object as child of the vpTransform 
• now the vpTransform is your clone

In Vega Prime 2.0 its now easier to do, as a new function was added vpObject::setCopySource(...), that is the direct equivalent to the old Vega  VGOBJ_CLONE

 

113   How can I Do an Intersection with a Particle Effect

 

Unfortunately with Vega Prime 1.x/2.0 you cannot currently perform an intersection test with Vega Prime based particle effects.

 

One rough work around is to:

• Create a Bill Board or Bounding Box or Bounding Sphere that Encompasses the Particle effect.
• Set the render mask on this bounding geometry so that it is not rendered
• Set the isector mask on the this bounding geometry
• Add this as child of the Particle effect

 

The bounding geometry is in the scene but not drawn which means you can intersect with it

 

114   How Can I find a Particular Face from my OpenFlight File

 

Unfortunately there is really no easy way to do this as Vega Prime or most other Scenegraphs as the do not load or store any name attributes of faces

There also no guarantee that your face would survive in its original form, as it may become part of a triangle strip, array etc when the file is load and optimized.

On crude way would be to have the Triangles/faces of interest modeled with one per group, then you could retrieve the face attributes in Vega Prime as long as there file was not optimized.

 

115  Can I use Line breaks in vsStrings

Unfortunately no, currently Vega Prime 1.x/2.0 does not support the use of Line Breaks ('\n') in vsStrings

You will have to uses seperate strings for each line

 

116   How do I get the Application Window Handle

 

This pretty straight forward, here's an example of how to do this on Windows ( On Irix and Linux just replace, HWND with the correct windows structure )

--

117  How Can I use Windows Send/Post Messages with Vega Prime 

 

This should be pretty straight forward, here's a possible way to do this

 

--

118   Where are Opengl State Calls Made in Vega Prime

In VSG  it is the virtual vsCullRecord::processDraw method that applies the Opengl State to geometry that is drawn through Render Strategies

The method checks the m_bLoadState flag and applies the state if it is not NULL. note, set the state to NULL on the geometry node if you don't want the state applied.

Render strategies only deal with "geometry" commands. You can, however, issue "state" commands within the strategy as well.

You can also consider deriving a new cull record / factory type and setting it on the geometry node. This way you get to control both methods of state applying. Take a look at the "Extending VSG" white paper for details on how to achieve this
 

119   How Can I Make an vpObject Transparent

There are several possible ways to make an object transparent.

Transparency may come from the Vertex color, Texture, or Material. Vega Prime will pick up these from the OpenFlight file. thus there is nothing special that you need to do at runtime if you have model it that way

Now if you want to modify what you've already modeled in your runtime application . then depending on the modeling technique, you will need to access the corresponding attribute at runtime in Vega Prime.

The Vertex color is stored in the color attribute of vrGeometry, the Texture and Material attributes are stored in a vrState, Therefore you will need to perform a scene graph traversal (or get hold of the geometry node somehow else), access those objects via the corresponding API calls (see vsGeometry), and then modify the corresponding attribute.

Its worth noting that some of the changes may not be multi-thread safe!!! , the vsgs_dynamic_geometry sample shows how to make it multi-thread safe).

The vp_flight_path web sample demonstrates how to "ghost" an entire object. In a nutshell, the sample implements a scene graph traversal that modifies vertex alpha and attaches alpha blend element to the state of the object

 

120   I'm Using VP Distributed but my Slave Objects are Not Updating

 

I have successfully setup my distribute my application but the models in my code are only being moved on the master computer and not on the slaved machines

You will need to tell the slaves to update the vpObjects, see the function vuDistributed::sync

Also see the following sample

$(MPI_LOCATE_VEGA_PRIME)\resources\samples\VegaPrime\vp\vp_distributed\vp_distributed.cpp

 

121   Uhh I get a Warning convColor : Color Hue <***> is out of range <**>- Forcing WHITE

 

If you are getting a warning message along the lines of: 

warn -> convColor : Color Hue <65025> is out of range <0..1024> - Forcing WHITE POLYGON

The color hue warning refers to possible corruption in the packed color indices of the flt file. The easiest way to get rid of the warnings would be to switch from indexed colors to RGB mode

In Creator or your modeling package edit the header of the database node of your flt file, check the RGB mode checkbox.

Or try and update the colour indices again in Creator

 

122   Can I use 3ds Max or Maya File in Vega Prime

 

Unfortunately as of Vega Prime 2.0 You cannot directly use files create in Maya or 3ds Max

You will need to first translate your models to a supported format such a OpenFlight using a third party product such as Polytrans or Deep Exploration. See ( FAQ 108 )

There are also some plug-ins to Maya and 3ds Max to output OpenFlight files which you can then use in directly Vega Prime, try a google to find them

 

123   Can I Create My Own Motion Model

 

Yes you can create your own Motion Model in Vega Prime

You can write your own from scratch, you can derive from vpMotion base class and you can even derive your motion model form one the motion models provided in Vega Prime

$(MPI_LOCATE_VEGA_PRIME)\resources\samples\VegaPrime\vpMotion\vpMotion_user

If you cannot find this sample contact MPI support as it may have been moved to their support only samples

 

124   What Happened to vsSequence

 

Vega Prime 1.0 and 1.1 supported a class and node type called vsSequence.

The vsSequence class and node were removed in Vega Prime 1.2 to be replaced with the vsAnimation calls and node which provides the same functions and methods.

 

125   How to Set the Loop Duration of Animation in Vega Prime

 

You can do some thing along the lines of in Vega Prime 1.x

 

 

--

See the vsAnimation documentation for more information 

Note that vsAnimation was called vsSequence in Vega Prime 1.0 and 1.1

Note in Vega Prime 2.0 ::findNamed(...)  has been changed to ::find_named(....)

 

126   Does Vega Prime Support P-Buffers

 

Yes Vega Prime does support P-Buffers

Vega Prime 2.0 added direct support for off screen P-Buffer Rendering

Vega Prime 1.x does not offer direct support of P-Buffers

 

127   Does Vega Prime Support 3d Textures

 

Yes Vega Prime does directly support 3d textures as of the release of Vega Prime 2.0

Vega Prime 1.x does not directly support 3d textures, although you can use them via Opengl in a draw call back etc.

 

128   Does Vega Prime Support Stereo Rendering  

 

Yes Vega Prime does support 2 Left & Right stereo rending as of the release of Vega Prime 2.0

In order to use stereo capability, it is required that the stereo feature be enable and the graphics card must be capable of rendering in stereo and many PC base cards need to be placed into stereo mode out side of Vega Prime

 

129  What Happened in to ::FindNamed() functions 

 

Well for some unknown reason MPI in the Vega Prime 2.0 release decided to change the name of the function findName(..) to find_name(..)

This is the type unnecessary API change that drive me nuts, it breaks my code and there really no good reason to it, as this breaks every customer code that use the function. Annoying Annoying and node needed

 

130  How to check if a vpObject is within a vpChannel's FOV 

 

You can do something along lines of : 

• Get channel frustum
• Compute object's bounding sphere in camera/view space
• intersect bounding sphere against the frustum. ( See vuVolume )

Note it is important that both the frustum and the bounding sphere are computed in the same reference frame (either world or camera).

MPI may have a sample so contact Support to see if they have

 

131    Changing the Channel Position Leaves Artifacts

 

I have vpChannel object in vpWindow, I  want to move it dynamically using say the arrow buttons. However it seems that vpWindow object redrawing only channel area so when I'm updating channel position I get  artifacts that do not disappear. 

technically the vpWindow class does no do any drawing at all,  It just provides the graphics context and canvas

The drawing is done by the vpChannel instances which define a region to draw into, the region is the only thing a channel can clear. That's why we can overlay channel etc..

One quick and dirty method would be to created an extra  dummy channel

The new dummy channel is then sized such that it fills the whole of the window and has an empty  scene and observer attached as we need the channel to be cleared for us,  there is little or next to no overhead from this

Then your the second, third channels etc  are then size and positioned as normal, you can then move these other channels around with out the artifacts being left behind

 

132   Can I use the Stencil Plane in Vega Prime

Here's an Example  of using a Stencil buffer in Vega Prime provided by  'Chas Whitley'
 

--

133   How can I keep my Vega Prime Window on Top

 

On a Microsoft Windows Based system you could do something like:
 

--

134  How Can I Move my Vega Prime Window to the Top 

 

On a Microsoft Windows Based system you could do something like:

 

--

135   Why is the SkyDome All Screwy when I at a High Altitude

 

Basically the SkyDome is currently Broken in Vega Prime.

Why is the Sky-Dome All Screwy when I have a High Altitude

While the sky-Dome is centred correctly positioned at the observer's X Y position, it's Z is currently always 0. This is a known issue to MPI, but as yet they have not fixed the problem

This is a real issue for most high flight applications, and will be worse the smaller your far-clip plane is

There is no real work around or fudge, MPI suggest pushing the far-clip out as this scales the sky-dome and thus will scale the Z. But this will effect the visual appearance of the clouds etc. and will effect your Z buffer by reducing  its precision and you will probably have to draw more as well if you push the far-clip out

Best course of action is to shout at MPI to fix the BUG.... MPI say this has been fixed in VP2.0 I still find it to be broken though

 

136   How Can I Group vgObjects

 

I have a set of vgObjects that I would like to moved around etc as a group, in Vega Classic I could have used a vgPlayer, but how do I do this in Vega Prime.

This is really easy in Vega prime and a lot easier than in Vega Classic, simply use and create a vpTransform then add the vpObject as children to the new vpTransform node.

Now you can move the vpTransform node, attach it to motion strategy, attach it to vpNavigator and the objects will stay positioned relative to the vpTransform

Also the really good thing is that you can easily reposition the vpObjects that are parented to the vpTransform, unlike old Vega Classic vgPlayer

Also see the Vega Prime FAQ 79

 

137  How Can I Pick Something in Vega Prime 

 

Contact MPI support department and request the sample called vp_picker which shows you how to create a basic picking class.

In Vega Prime 2.0 see the header vgEventPicker.h this uses a simple version of the code found in vp_picker

Note neither of these provides much of the extra useful functionality you could find in the vgPicker and Vega PickFly motion models, they are simply a basic pick event

 

138   Where is the Equivalent to vgPicker  in Vega Prime

 

Vega Prime 1.x does not provide any direct equivalent to the vgPicker class found in classic Vega


MPI does have a simple picking sample written when I still worked at MPI called vp_picker, contact MPI support and ask for this sample.

In Vega prime 2.0 vgEventPicker.h provide an even simpler picking ability.

Note neither of these provides much of the extra useful functionality you could find in the vgPicker and Vega PickFly motion models, they are simply a basic pick event

 

139   Should I Use Multiple Windows or Multiple Channels

 

One Window with Multiple channels is better than Multiple Windows with a channel per windows

(more info to follow )

 

140    Can I Limit process Shown by the 'drUtil' Tool

 

Vega Primes Distributed Rendering module provide a tool called drUtil, this tool allows the use to display all the process running on the system ( similar to the Windows Task Manager)

Is it possible to limit the process it shows, as the tool allows you to attempt to delete any of the listed process, which can cause many problems to say the least

Unfortunately there is no way currently in Vega Prime to limit which processes are shown ( as of Vega Prime 2.0 )

 

141    How to Load Files from Another Thread

 

I want to load files for my application in different thread threads, how can I achieve this in Vega Prime

There are several  ways to solve this problem, two  of which could be:

• You could use asynchronous loading method that is already built into Vega Prime, whish means very little work on your part
   
• You could implement your own paging service, which is more work than the previous methods. Contact the MPI support and ask for the vsgs_paging_service sample, this sample illustrates how to configure an asynchronous paging service

 

142   Does Vega Prime Provide any Shadowing Capabilities

 

Vega Prime 1.x does not offer any direct support for creating and using shadows, although as normal you can write you own code to do this

While Vega Prime 2.0  provides the technique of "Planar Shadows"

Planar shadow is a quite simple technique that allows the shadow caster to be projected onto a surface along the direction of the light source.

Not one of the artefacts/problems with this technique is that If the shadow moves from one plane/surface to another you will see some shadow discontinuity when the slope of one plane changes with respect to the other plane.

While this shadow technique is inexpensive, like all other techniques for producing shadows, it has its side-effectsVega Prime 1.x does not offer any direct support for creating and using shadows, although as normal you can write you own code to do this

 

143   Can I change the Cursor Shape in a Vega Prime Window

Yes you can but you cannot do this directly through Vega Prime , as the cursor is tied directly to the GUI kit you are using, so the remit to change the shape fall sdown to the GUI API and SDK.
 

--

144   How to get the vpPipeline of a vpWindow

 

While, a Vega Prime pipeline knows about its Vega Prime windows,  a window does not know about its pipeline.

Therefore, you need to iterate over all pipelines and search for one that has the window, something along the lines of the code below:
 

--

145   Can I Change an Embedded Vega Prime Windows Parent  

 

It is really not possible to dynamically change the parent of an embedded Vega Prime Window.

One work around that I can thing of would be to use a dummy window that is to create an extra window/widget that holds the Vega Prime window, this way you can reparent the dummy window and bring the Vega Prime window along with it, you may have to also make sure about route windows messages correctly

 

146   Can I Use a Splash Screen Like Vega Classic

Unfortunately Vega Prime does NOT provide a Vega Classic Splash Screen.


If you want to have a splash screen in Vega Prime then you are going to have to create you own.
 

147   How do I Compile Vega Prime Statically

 

There are several steps that you have to follow in order to statically compile a Vega Prime based application

See the sample that is shipped with Vega Prime  can be found at:

$(MPI_LOCATE_VEGA_PRIME)/resources\samples\VegaPrime\vp\vp_static_link

This sample will show you how to set up your makefile's, work spaces  and how to include loader formats in order to be able to compile statically

If you cannot find this sample then contact MPI support directly ( but it is a shipped sample )

 

148   How can I transform my Mouse from Screen to World Coordinates

 

We can do this by using code along the lines of

We need transform the mouse position  which is in normalized channel  screen space, back into world space.  

In order to accomplish this,  we need to undo"the projection and graphics library specific offset transformations by transforming the point through the inverse of their respective matrices.  

This gives us the mouse position in the eye's coordinate system.  Then a final transformation through the view matrix will put us into world coordinates.  

Note that in the initial transformation that the Z coordinate really does not matter since the inverse of the projection transformation ignores it

mx and my are is the position of the mouse in channel  coordinates
 

--

The Mouse position ( mousePos ) is now in world space coordinates

 

149   How do I Calculate the Vertical Field of View

 

I know that Vega Prime will calculate the Vertical Field of View if I give the Vega Prime channel a Horizontal field of view and pass -1 for the vertical field of view

Here's one way that you could do this is along the following lines:

 

150   How do I Calculate the Horizontal  Field of View

 

I know that Vega Prime will calculate the Horizontal Field of View if I give the Vega Prime channel the Vertical field of view and  pass  -1 to the Horizontal field of view

Here's one way that you could do this is along the following lines:
 

© Copyright 2005-2006 Gordon Tomlinson  All Rights Reserved.

All logos, trademarks and copyrights in this site are property of their respective owner.