How to use sdf's as bounding boxes for forces?

FUSE question
1

Textures To Particles with control2.vl (72.6 KB)

Moved from matrix…
I’m trying to use a bounding box for forces, seems to be a fairly common need, coming from c4d or games I’d think, wind when you leave a building for example. Ideally with fall off. This patch is using textures as vector field as a starting point, but only to emit particles. And I was trying to use an SDF to activate the curl force, but adding examples as @texone has suggested, makes the simulation stage throw errors, of
Could not compile shader. See error messages.[shaders\Shader_2110393184.sdsl(141,47)]: Error: E0227: Unable to find stream variable [PositionWS] in class [Shader_2110393184]
[shaders\Shader_2110393184.sdsl(141,47)]: Warning: W0003: Unable to find type reference for member [streams.PositionWS]
[shaders\Shader_2110393184.sdsl(141,47)]: Error: E0227: Unable to find stream variable [xyz] in class [Shader_2110393184]
[shaders\Shader_2110393184.sdsl(141,47)]: Warning: W0003: Unable to find type reference for member [streams.PositionWS.xyz]

But I’ve also seen

Could not compile shader. See error messages.Error: C:\Program Files\vvvv\vvvv_gamma_5.2-0016-g7a8f596b6a\log\shader_ComputeFXEffect_cea16ae793cff792e2007a6fa92e0be5.hlsl(191,31-85): warning X3203: signed/unsigned mismatch, unsigned assumed
C:\Program Files\vvvv\vvvv_gamma_5.2-0016-g7a8f596b6a\log\shader_ComputeFXEffect_cea16ae793cff792e2007a6fa92e0be5.hlsl(196,39-56): error X3018: invalid subscript ‘PositionWS’

With the other suggestion

I’ve left the simulation stage unattached, so you should see some particles spawn and respawn after 8 seconds. Attach one the group nodes for errors

2

Textures To Particles with control3.vl (73.2 KB)

So detaching the positionWS node makes the shader work, but then you get no bounding box effect, the if is just true.

3

image

  1. You need to use the particle position attribute to sample the sdf

  2. PositionWS is a draw shader semantic that in this case is not set

1 Like
4

Perfect, without the if region and straight into the strength of the curl force works as a softedge too, wonderful thank you!