IVF Use Stereo question and multVec question

IVF Use Stereo question and multVec question

Post by Wang » Thu, 12 Jun 2003 17:55:30



Hi

I have a question about the stereo feature of the IVF. I'm using
Windows 2000, Visual C++.NET and TGS Open Inventor 3.0.

I would like to show some stereo effect using a Dresden 3D display
system. I guess I should use the "vertical interlaced" method but not
sure. (Right click --> Preferences --> Stereo.. )

Because I'm using a very big terrain as the background for a f16
model, I guess the Stereo feature mentioned above automatically set
the focus on the terrain. The result is that the distance between the
2 f16 views are way too big to generate a possible stereo effect. I
noticed there is a "camera offset" slidebar but since the movement
scale is too big for the f16 model I have no choice but to slide it to
0. Otherwise the f16 will just disappear.

I wonder if there's a way for me to set the focal distance of the
camera myself when I use this Right click --> Preferences --> Stereo..
 method?

When I select "Use Stereo", is the focal distance changing when I zoom
in and out? In order to achieve a desired stereo effect, do I have to
fix my viewing point?

Is there any document describing how this Right click --> Preferences
--> Stereo..  function works? (I'm sorry I really don't know how to
call it so just put it this way.)

A second question is about the SbRotation::multVec method. I want to
know how exactly it works. I noticed that the description in the help
file is very sketchy (only "Multiplies the given vector by the matrix
of this rotation. ") And I searched all the example codes I have and
only found one occurance of multVecMatrix actually, and without
explanation. (Mentor 10.2 setEventCB.cxx )

I'm asking this because I want to set camera's up direction and did
found an explanation in the forum (5th June 2003 answered by Morten
coin3d). But still don't know the exact meaning of this function.

If ROTATION.multVec(VECTOR1, VECTOR2), what happened to ROTATION and
VECTOR1 and VECTOR2? Why Morten wrote "camerarotation.multVec(lookat,
lookat);"? Is that the vector "lookat" modified and the result saved
in the same vector?

If MATRIX.multVec(VECTOR1, VECTOR2), is the result same? Is it that
MATRIX is not affected, VECTOR1 is left-multiplied by MATRIX and
result saved in VECTOR2? Is my guessing correct? Why isn't this key
information not included in the help?

Is there any devoted example to show how to do matrix multipication? I
really feel this "guessing" way of learning is not right.

 
 
 

IVF Use Stereo question and multVec question

Post by Wang » Fri, 13 Jun 2003 10:05:57


The Help I used was from TGS. I use "sbrotation::multvec" as keyword
to search in google, and found out there's also explanations in coin3d
website (an online help), and although the format is identical to the
TGS Open Inventor help, the content is quite different. It's much more
helpful.

It reads:

Rotate the src vector and put the result in dst.

It is safe to let src and dst be the same SbVec3f instance.

Also the explanation to "multVecMatrix" is different. coin3d help
reads:

Multiply src vector with this matrix and return the result in dst.
Multiplication is done with the vector on the left side of the
expression, i.e. dst = src * M.

It is safe to let src and dst be the same SbVec3f instance.

This method can be used (using the current model matrix) to transform
a point from an object coordinate systems to the world coordinate
system.

Which obviously is much better than just "Multiplies given row vector
by matrix, giving vector result. "

 
 
 

IVF Use Stereo question and multVec question

Post by Morten Erikse » Fri, 13 Jun 2003 17:00:28



> [...] found out there's also explanations in coin3d website (an
> online help), and although the format is identical to the TGS Open
> Inventor help, the content is quite different.

Just to clarify: Coin is an independent implementation of the Open
Inventor API, and we have also written new documentation from scratch.

Quote:> It's much more helpful.

Thanks. :-)

Morten
--
<URL:http://www.coin3d.org>