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alesmav
04-12-2003, 05:05 PM
Let say we have a 20 x 20 poly cube grid. Then I put on a texure that stretches across all those cubes. Now a I want to drive a Translate Y attribute of each indvidual cube based on a luminance value on the assigned texture. For example, if a brighter part of a texture falls on a cube, it it has higher translate Y value than the cube with a darker part of the texture. No displacement tips please. I would like pure texture values to drive the translation. Is this possible with Maya. Been messing around with it for quite some time, but couldn't find an appropriate solution. Maya has a lot of utilities to drive the texture, how about textures driving things?

thnx

ALES

mestela
04-12-2003, 07:23 PM
Similar to the x-men pushpin map right? I'm not sure about driving objects directly through textures (I've not needed to), but you can drive particles in this way, then use geometry instancing to bind objects to the particles.

You'll need julian mann's great solidTexSampler plugin, its over at www.highend3d.com. Once installed, create a particle grid on the ground plane, and run the jSolidTexSampler script. It creates a projected ramp which drives particle colour. Rotate and scale the projection so it lies correctly over your particle grid (you'll probably need to rotate it -90 in x), then adjust the runtime expression so it's something like


vector $pos = particleShape1.position;
vector $texSample = solidTexSampler1.colors;
particleShape1.position = <<$pos.x, $texSample.y, $pos.z>>;


If you play the scene, you'll see the particles will now raise in Y corresponding to the green channel of the ramp. You can rotate/scale/translate the 3dprojection, or properties of the ramp, and the particles should respond in real time.

You can now replace the ramp with a file texture, or a sequence of images, then instance cubes to the particles. That's the short version, I'm planning to write a tutorial to explain all that a little better.

Cheers,

-matt

alesmav
04-12-2003, 07:57 PM
Ok, got the picture... Particles crossed my mind, but you got a little further. Will test it out. Thnx a lot!

ALES

beaker
04-13-2003, 08:30 AM
The couple guys that wrote the plugin for doing the Mystique transformations sell them and have demos of them on their website here:
http://www.kolektiv.com/
It allows you to drive non linear transforms with a texture.
There is a demo movie of the plugins/effect here:
http://www.kwcc.com/movies/xmenT1.mov

mestela
04-14-2003, 05:31 PM
Oooh yeah, the kolektiv plugins are way cool, if you have the cash and do lots of fx style shots, they're a godsend.

Alternatively, I was just browsing the other forums and found this little tidbit. There's a new command in 4.5 called colorAtPoint, its documentation wasn't added by mistake. It might allow you to do what you need without plugins or expressions. Maybe...

http://www.cgtalk.com/showthread.php?s=&threadid=54680

-matt

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