Q: Normals perpendicular to camera

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Good morning,

was reading up on this page and tried to replicate his scene.

http://adamswaab.wordpress.com/2010/02/23/houdini-particle-aura/ [adamswaab.wordpress.com]

Not being a vop expert, i tried to get as far as i could. I attempted to source particles using the ‘emit attribute’ calculated within the vopsop.

Frankly don't have a solid understanding about the calculation happening within it. Would be awesome if someone share some insight!

Thank you.

eitht.

Attachments:
normal_perpendicular_to_cam_vopsop.hipnc (117.6 KB)

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and what seems to be the problem?
set Initial Velocity on Source POP to Inherit Velocity and put like 0.01 in there
seems to emit correctly from camera relative edges

is it not what you wanted?
Tomas Slancik
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Method Studios, NY
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Maybe i am understanding his set up wrongly. In the video he was able to source particles from the profile of the teapot… While my example file still had lots of stray particles on the body of the teapot, i suspect our numeric values inside the vopsop are different.

Plus his particles only emits off the teapot's profile which is visible to the camera, do i have to perform some sort of backface culling?

Hope i dont sound confusing…

Also, thank you tamte for replying!

eitht.

Attachments:
pop.jpg (67.7 KB)

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you can just tweak the ramp curve on the VOP SOP to isolate the region you want the particle to appear in
right now it is linear falloff from perpendicular to parallel so you will have some points across the whole surface

Attachments:
normal_perpendicular_to_cam_vopsop_fix.hipnc (126.2 KB)

Tomas Slancik
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Method Studios, NY
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Yayyy tamte, that's it! /thumbs up

eitht.
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