deformed gravity，need help

[YY3010966]

hi, everyone . im a new houdiner,there is a question need help

 

i wanna create a custom  force always point to surface normal,like a  deformed graivity,it could pull particle back like common gravity,the difference is the different ground position has different gravity dirction ,not always point to -Y direction.it should work just like real earth. 

 

i attach an image ,the red arrow mean the direction of gravity,and balck circle mean object surace.sorry for my ugly drawing.

 

any help will be appreciate.

[ikarus]

If you attach sdf volume data to a field force dop it will create a force with the direction of the gradient of the sdf.

[narbuckl]

Yeah, exactly what Ray said, create an SDF volume of your surface, get the volume gradient, normalize it, add to velocity.

 

HAI RAY! xD

[YY3010966]

@ikarus,@narbuckl:
 
thanks guys for u suggestion,bcoz im total new to hoduini,i understand the idea u said,but dont  know how make it done.
sdf mean isoffset SOP?gradient of sdf mean wt?  sorry for my idiot

 

could u attach a simple example hip?  thanks

[YY3010966]

attach file is wt i did ,but pretty far away i want.

test.hip

[narbuckl]

Here is an example of a deforming animated shape where I used the SDF as the force in the particle simulation. Hope this helps


 

sdfForce_example.hip

[YY3010966]

Here is an example of a deforming animated shape where I used the SDF as the force in the particle simulation. Hope this helps

 

thank u so much,narbuckl, u r so kind .

 

but the hip didnt work for me . no particle appea  and throw error at pop solver .

 

u  use ver13 ?   my version is 12.5.could u explain how it work?

 

anyway,thanks