question

Andrew Wilkins avatar image
Andrew Wilkins asked ·

Set Parameter - HtoA

Good day,

Currently working on some operator graphs in HtoA—I've noticed that "geometry / procedural" Arnold Visibility are quite un-intuitive to use.

The first "port of call" would be using the listed parameter name, such as:
ar_visibility_camera
ar_visibility_shadow
ar_visibility_diffuse_transmit
etc.

Alongside reading the HtoA Documentation:
https://docs.arnoldrenderer.com/display/A5AFHUG/Set+Parameter

operators.jpg

One would assume we'd write the assignment as:
ar_visibility_camera = False

This however doesn't work.

Only on further digging, I've noticed that "Visibility" is using a "bitmask" format?
(random post from 2020)
Which complicates would should otherwise be quite simple...
This bitmask method doesn't seem to be noted in the documentation?

Would be nice to get some clarity here.


All the best,

Andrew

operators
operators.jpg (83.6 KiB)
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Stephen Blair avatar image
Stephen Blair answered ·

https://docs.arnoldrenderer.com/display/A5AFHUG/Operators

  • Kick can be used to query possible target node parameter names of a set_parameter node.

https://docs.arnoldrenderer.com/display/A5NodeRef/shapes

  • visibility values are documented here

https://docs.arnoldrenderer.com/api/arnold-6.2.1.1/group__ai__ray.html

  • The hexadecimal values for the ray types are here


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Great, thanks for the info. Appreciated!


PS. Could be worth placing these links in the DCC docs. I rate most users would mainly read the DCC specific documentation.

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Stephen Blair avatar image
Stephen Blair answered ·

The "ar_" prefix isn't part of the Arnold parameter names, that's just something used in Houdini for spare parameters.

Set Parameter works on Arnold parameters, and you have to use Arnold parameter names (you can list them with kick, see below).

For visibility: https://arnoldsupport.com/2018/11/21/backdoor-setting-visibility/

polymesh parameter names:

C:\Program Files\Autodesk\Arnold\maya2022>bin\kick -info polymesh
node:         polymesh
type:         shape
output:       (null)
parameters:   48
filename:     <built-in>
version:      6.2.1.0

Type          Name                              Default
------------  --------------------------------  --------------------------------
BYTE          visibility                        255
BYTE          sidedness                         255
BOOL          receive_shadows                   true
BOOL          self_shadows                      true
BOOL          invert_normals                    false
FLOAT         ray_bias                          1e-06
MATRIX[]      matrix                            (empty)
ENUM          transform_type                    rotate_about_center
NODE[]        shader                            (empty)
BOOL          opaque                            true
BOOL          matte                             false
BOOL          use_light_group                   false
NODE[]        light_group                       (empty)
BOOL          use_shadow_group                  false
NODE[]        shadow_group                      (empty)
STRING[]      trace_sets                        (empty)
FLOAT         motion_start                      0
FLOAT         motion_end                        1
UINT          id                                0
UINT[]        nsides                            (empty)
UINT[]        vidxs                             (empty)
UINT[]        polygon_holes                     (empty)
UINT[]        nidxs                             (empty)
UINT[]        uvidxs                            (empty)
UINT[]        crease_idxs                       (empty)
FLOAT[]       crease_sharpness                  (empty)
BYTE[]        shidxs                            (empty)
VECTOR[]      vlist                             (empty)
VECTOR[]      nlist                             (empty)
VECTOR2[]     uvlist                            (empty)
BOOL          smoothing                         false
ENUM          subdiv_type                       none
BYTE          subdiv_iterations                 1
FLOAT         subdiv_adaptive_error             0
ENUM          subdiv_adaptive_metric            auto
ENUM          subdiv_adaptive_space             raster
BOOL          subdiv_frustum_ignore             false
ENUM          subdiv_uv_smoothing               pin_corners
BOOL          subdiv_smooth_derivs              false
NODE[]        disp_map                          (empty)
FLOAT         disp_padding                      0
FLOAT         disp_height                       1
FLOAT         disp_zero_value                   0
BOOL          disp_autobump                     false
BYTE          autobump_visibility               1
FLOAT         step_size                         0
FLOAT         volume_padding                    0
STRING        name


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Hello,


Thanks for the info!

I'm just wondering why this isn't in the official documentation? I think most users won't find a arnold support post from Nov 2018 nor use Kick to find this extra information.

Even then it's not intuitive to use the "visibility decimal values" and in most cases "custom set parameter" needs to be built in order to control these parameters efficiently with artists.
(So they just see check boxes & aren't required to type in selection and assignment expressions)

Would be ideal if the Set Parameter had some pre-setup common parameters.

AKA:
set-parameter.jpg

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