How do I get obj's velocity in Vop Vex Surface?

[cloudfx]

Hi all,

I have an animated character and he kicks and punches.

I would like to get the character's prim velocity or point velocity in vop vex, so I can multiply it to opacity.

What I am trying to do is faster velocity area gets high opacity and lower velocity area gets low opacity.

Here is the set-up I have done for now..

What should I add to it?

Thanks a lot!

Edited July 31, 2008 by Jae Yoo

[Jason]

Hi all,

I have an animated character and he kicks and punches.

I would like to get the character's prim velocity or point velocity in vop vex, so I can multiply it to opacity.

What I am trying to do is faster velocity area gets high opacity and lower velocity area gets low opacity.

Here is the set-up I have done for now..

What should I add to it?

Thanks a lot!

Do you want to drive the refraction intensity (Kt) with the magnitude of the velocity? Or do you want to blend two materials - glass and something else based on the magnitude of velocity?

[cloudfx]

Do you want to drive the refraction intensity (Kt) with the magnitude of the velocity? Or do you want to blend two materials - glass and something else based on the magnitude of velocity?

Hi, Jason.

Refraction strength and opacity value.

Thanks,

[Jason]

Hi, Jason.

Refraction strength and opacity value.

Thanks,

Okay, take a look at this simple example. I've driven three shaders by the 'v', which I've calculated in SOPs with a Trail SOP.

Mixing shaders, ramping off Kt, and fading off the object (by reducing Of and Cf by the v magnitude).

The Fit Range VOP in there is just to map the v magnitude to a decent 0-1 range. This will vary a lot based on your scene and your needs.

drive_material_by_v.hipnc

[cloudfx]

Okay, take a look at this simple example. I've driven three shaders by the 'v', which I've calculated in SOPs with a Trail SOP.

Mixing shaders, ramping off Kt, and fading off the object (by reducing Of and Cf by the v magnitude).

The Fit Range VOP in there is just to map the v magnitude to a decent 0-1 range. This will vary a lot based on your scene and your needs.

Hi, Jason.

Thanks a lot!

I got one more additional question,

My animated character seems like it does not have big difference between the faster area and the slower area.

I mean, there is difference between them.. but Its really slight.

Is there any way to exaggerate the value like smaller value 1 -> 1.324 and stronger value 10 -> 223.34?

Thanks,

-j

[SpencerL]

Hi, Jason.

Thanks a lot!

I got one more additional question,

My animated character seems like it does not have big difference between the faster area and the slower area.

I mean, there is difference between them.. but Its really slight.

Is there any way to exaggerate the value like smaller value 1 -> 1.324 and stronger value 10 -> 223.34?

Thanks,

-j

you can use a fit function to expand your magnitude range. You need to enter the original min and max values of your mag followed by your new min and max values.

fit($YOUR_MAG, 1, 10, 1.324, 223.34)