# wixman

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Peon
1. ## Learning VOPSOP

Ahhh - good suggestion. I'm going to attempt this in a few
2. ## Learning VOPSOP

Care to share your network shinji?
3. ## Learning VOPSOP

Here's my attempt. I used 3 seperate vop sops, but I could have probably reduced that. With one of them I setup lambertian shading (clamped dot product of surface normal with light ray), with the 2nd I setup up the shadow casting (intersect, using the vector from the light source to the point position), and with the 3rd I just did some smoothing/blurring with a point cloud.
4. ## Learning VOPSOP

I'm pretty sure pcopen stops once it reaches the set number of points, in this case I had it set to 1.
5. ## Learning VOPSOP

It does! - getting a cook of 13.51ms with the nearpt setup vs a cook of 18.40ms with pcopen. Good to know!
6. ## Learning VOPSOP

Hey Captain - to be honest, the only thing that looks out of the ordinary here is the nearpt/getattrib here. We just need a vector from our current position (P) to the nearest point on the cylinder. Also, use the 'trigonometric functions' node for the sin - the key here is to crank up the frequency to increase the number of beams.
7. ## Learning VOPSOP

Could you post an image of your result? This is pretty much the network I had in my first attempt - the size of my beams wasn't consistent without the arccos
8. ## Learning VOPSOP

I've attached an image of my network. Presumably, if it's not working when you move the tube around, something is wrong with the point cloud look up. Because if it finds nothing, the lines will fan out from center (0,0,0). What the dot product is essentially doing is comparing the two (normalized) vectors, and giving the cosine of the angle between them: 1 if they're the same direction, -1 if they're opposite direction and 0 if they're perpendicular. The arccos gives the actual angle between the two vectors in radians (from 0 to pi) I've done this in an attribvop, which has opinputs as globals making the point cloud lookup a bit simpler.
9. ## Learning VOPSOP

Ok, I think I got there. (Took the arccos of my dot, then plugged that into the sin)
10. ## Learning VOPSOP

Thanks! Well that's good to know - I guess it's possible to use the cross for this (?) as the length of the cross is the sin of the angle between the two vectors multiplied by their lengths
11. ## Learning VOPSOP

A little late to the party. Having a quick go at this one. Not used the cross product yet, just dotting the vector from P to the nearest point on the cylinder with another planar vector (1,0,0) and putting that into a sin. Looks like I'm not quite there though.
12. ## RBD Packed Object Pivot/Angular Velocity

Hey - I'm having problems setting the pivot on the rbdpackedobject dop, so when I add an initial angular velocity, my pieces fly off. I can add a pivot point attribute (which is essentially the start position of each packed prim) but I'm not sure how to get the dop sim to honour this.
13. ## Get point number based on ID or other attribute

done. phew. PATH_DEFORM_TEST.hipnc
14. ## Get point number based on ID or other attribute

I'm trying to get the same effect as copying spheres to the original particle system but with the geometry deforming to match the arc of motion. So I was creating ribbons to creep the spheres across using a secondary particle system
15. ## Get point number based on ID or other attribute

Bah! Tried for a bit, but couldn't get it to work! Would you mind looking at my test scene? Look in the 2nd foreach for a sticky with a note PATH_DEFORM_TEST.hipnc
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