Re: Help with textures.

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Brian Furtaw (brian++at++sgi.com)
Tue, 4 Feb 1997 10:05:25 -0500

Eric, I made some changes to your inventor file and attached a copy of the one
I used to test. You have to do two things here first tell Inventor to use
repeat as the texturing method which is the default but I added it anyway, see
below. Second do not forget about those texture coordinates, the SoCube defines
them for you so you can't modify them with SoTexture2Coordinate so you change
the SoTexture2Transform, I simply scaled the V coordinates by 5x to give the
desired effect.

Brian

On Feb 4, 12:52am, Eric Heft wrote:
> Subject: Help with textures.
> Hi,
>
> Here is the *SHORT* form of the question?
>
>
> I want an object is 50'x10' and I have a texture thats
> 10'x10' and I want the texture to be duplicated 5 times
> rather than stretched out?
>
> Here's the background info, at the end is the inventor
> model file I'm using. You can search for "GOTOMODEL" to jump
> directly to the model.
>
>
> I'm using performer to run an experiment that
> involves displaying a texture on a rectangle and
> checking how texture affects speed perception. To
> get good data, it's critical to know things like :
>
> Where exactly on the screen the target is placed.
> How to move the target with known some velocity.
> How to make the target a given color.
>
> I've got a pretty good handle of the first two,
> but the third has turned out to be tricky. For our
> pilot study we are using a rectangle thats 50'x10'
> projected 500'. Later we will use different aircraft
> but I don't have to worry about that yet :)
>
> For the pilot study we need that completely specify
> whats seen on the screen. Which to me seems like it
> can be handled easily by a rectangle thats got a texture
> on it so, I scrapted together an inventor model.
>
> The problem is it also stretches out the texture. So how
> do I get the texture to be duplicated five times across the
> surface of the object?
>
> I'm also having problems picking up information about
> the mapping of pixels drawn on the screen to those dumped
> by snap_image. I'm thinking its probably that I have anti-alias
> on! :)
>
> #Inventor V2.0 ascii *GOTOMODEL*
>
> Separator {
     Texture2Transform {
          translation 0 0
          rotation 0
          scaleFactor 1 5
          center 0 0
     }
> Texture2 {
> model DECAL
> filename "texture.rgb"
          wrapS REPEAT
          wrapT REPEAT
          model MODULATE
> }
> Material {
> ambientColor 1.0 1.0 1.0
> }
> Transform {
> translation 0 0 0
> scaleFactor 10.0 50.0 0.1
> }
> Cube {
> }
> }
>
>
> Thanks for getting to this point! ;)
>
> Eric Heft
> =======================================================================
> List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/
> Submissions: info-performer++at++sgi.com
> Admin. requests: info-performer-request++at++sgi.com
>-- End of excerpt from Eric Heft

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Brian Furtaw  (brian++at++sgi.com)	
VisSim  Technical  Consultant
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Silver Spring, Maryland 20904  OpenGL/ImageVision/OpenInventor/Performer

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