Tag Archives: Arnold

Another case of a missing entry point

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entry_point_not_found
In this case, a user installed the latest MtoA, but when he went to load mtoa.mll in the Plug-in Manager, he got this error:

---------------------------
Settings/Preferences: maya.exe - Entry Point Not Found
---------------------------
The procedure entry point ?IsRenderablePath@CArnoldSession@@SA_NVMDagPath@@@Z could not be located in the dynamic link library mtoa_api.dll.

From past experience, I knew that the problem was probably the Maya.env file. And sure enough, it looked something like this:

MAYA_RENDER_DESC_PATH = C:\solidangle\mtoadeploy\2013.0.22.0
PATH = %PATH%;C:\solidangle\mtoadeploy\2013.0.22.0\bin;
solidangle_LICENSE=5053@SOLIDANGLE-PC

MAYA_RENDER_DESC_PATH = C:\solidangle\mtoadeploy\2013.0.22.1
PATH = %PATH%;C:\solidangle\mtoadeploy\2013.0.22.1\bin;

Notice that there are two MAYA_RENDER_DESC_PATH and PATH settings. Maya reads just the top two, which are for an older version of mtoa, so when Maya loads mtoa.mll we end up with a “missing entry point” error.

How did this happen? Well, in this case, in-between installs and uninstalls of different versions MtoA, the user had updated Maya.env with his own MAYA_RENDER_DESC_PATH and PATH settings for MtoA. And then the next install of MtoA appended its own settings to the Maya.env file.

The MtoA Installer works like this:

  • Installs make a backup of the existing Maya.env, and then append the environment settings to the existing Maya.env.
  • Uninstalls restore the backup version of Maya.env.

So if your Maya.env already has MtoA settings for MAYA_RENDER_DESC_PATH and PATH settings, then when you install another MtoA, you end up with a problem (because the new settings will be at the bottom, where they are ignored).

Ok, so that’s problem solved. Just remove those extra entries from Maya.env.

[SItoA] Expressions for standins of animated sequences

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A standin can load an animation sequence, such as circling_cubes.[1..25].ass.
For example, if you open an Arnold_Standin property, click Browse, and select a sequence, Softimage automatically inserts a [Frame] token into the file name:

standin-path

By default, that [Frame] token resolved to the current frame, but you can override that and use an expression to drive the sequence.

For example, if you have a 25-frame sequence of ASS files, you may want to play the 25 frames and then stop. To do that, you could use this expression:

 
MIN(Fc,25)

If you wanted to continuously loop the 25 frame sequence, you could use an fmod (modulo) expression like this:

 
cond( fmod( Fc, 25 ) == 0, 25, fmod(Fc,25) )

And if you wanted to show just frames 10 to 25, you could use this expression:

 
cond( Fc<10 , 10 , MIN(Fc,25) )

If you’re not sure about these expressions, try playing with them in the Expression Editor. As you move through the timeline, watch the Current Value update in the Expression Editor.
fmod_expression

[MtoA] Creating color masks with a custom AOV and the Utility shader

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In this video, I show how to a color mask AOV using a custom AOV and the Utility shader. Topics covered include:
– Creating a custom AOV
– Setting the default shader for a custom AOV
– Setting up the Utility shader to output a color for each shape
– Understanding the difference between the Color and Color ID color modes

https://vimeo.com/63433605

[MtoA] Recipe for linear workflow

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Ingredients

  • 1 x Maya
  • 1 x MtoA
  • 1 x Monitor calibrated to sRGB
  • Linear textures

Procedure

  1. In the Render Settings, set all the Arnold gamma correction settings to 1.0.
    ArnoldRenderSettingsGamma
  2. Set your Render View > Display to 32-bit floating-point (HDR).
  3. Click Render View > Color Management, and in the viewColorManager Attribute Editor, set the Image Color Profile to Linear sRGB (that is, your input textures are in linear space).
    ColorManager
  4. Render to EXR or some other linear floating point format.

hat tip: Fred

Just for kicks: Printing out shading trees

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kick -tree prints the shading network for a shader node. For example, given this:

polymesh
{
 ...
 shader "Sources.Materials.DefaultLib.Material.standard.SItoA.41000.1" 
 ...
}

standard
{
 name Sources.Materials.DefaultLib.Material.standard.SItoA.41000.1
 
}

You can print out the shader tree for the standard shader like this:

set ASS_FILE=//Projects/Support/Arnold_Scenes/example.ass
set NODE=Sources.Materials.DefaultLib.Material.standard.SItoA.41000.1
set SHADER_PATH=%SITOA_BIN%
%KICK_PATH%\kick.exe -tree %NODE%  -i %ASS_FILE% -l %SHADER_PATH%

For a [simple] shading tree that looks like this:
SimpleTree
You would get this:

standard:Sources.Materials.DefaultLib.Material.standard.SItoA.41000.1
  |
  +-Kd_color = txt2d_image_explicit:Sources.Materials.DefaultLib.Material.Image.SItoA.41000.2
  |   |
  |   +-tex = sib_image_clip:Sources.Materials.DefaultLib.Material.noIcon_pic.SItoA.41000.3
  |
  +-opacity = txt2d_image_explicit:Sources.Materials.DefaultLib.Material.Image.SItoA.41000.2
      |
      +-tex = sib_image_clip:Sources.Materials.DefaultLib.Material.noIcon_pic.SItoA.41000.3

max depth:       2
total shaders:   5
cycles detected: 0

shader counts:
  2 txt2d_image_explicit
  2 sib_image_clip
  1 standard

one-to-many connections:
  2 txt2d_image_explicit:Sources.Materials.DefaultLib.Material.Image.SItoA.41000.2
  2 sib_image_clip:Sources.Materials.DefaultLib.Material.noIcon_pic.SItoA.41000.3

Notice that txt2d_image_explicit and sib_image_clip are counted twice, because those branches are plugged into two different ports on the standard shader.

[SItoA] Applying materials to standins

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In Softimage, a standin object is the polygon mesh, hair, or point cloud with the Arnold_Standin property.

If you apply a material to a standin, that material will override any materials specified in the ASS file referenced by the standin. If you don’t want that to happen, give your material a name that starts with “Scene_Material” or “Standin_Material” (it doesn’t matter if you use uppercase or lowercase for the names).

If you do that, the standin object will use that material, but the objects in the ASS file will use the materials saved in the ASS file.

Here’s what you get in an exported ASS file. If SItoA finds a standin with a material name that starts with “scene_material” or “standin_material”, it exports a procedural node with no material.

procedural
{
 name standin-cube.SItoA.41000
 dso "\\server\project\Arnold_Scenes\XSI_Man.ass"
 min -4 0 -4
 max 4 0 4
 matrix 
  1 0 0 0
  0 1 0 0
  0 0 1 0
  0 0 0 1 
}

Otherwise, if you name the standin material something else, the procedural node will include a shader node for that material:

procedural
{
 name standin-cube.SItoA.41000
 dso "\\server\project\Arnold_Scenes\XSI_Man.ass"
 min -4 0 -4
 max 4 0 4
 matrix 
  1 0 0 0
  0 1 0 0
  0 0 1 0
  0 0 0 1 
 shader "Sources.Materials.DefaultLib.Test.standard.SItoA.40000.1" 
 declare procedural_shader constant ARRAY NODE
 procedural_shader "Sources.Materials.DefaultLib.Test.standard.SItoA.40000.1" 
}

Switching between different versions of MtoA

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If you have several versions of MtoA, you can switch between them by editing your Maya.env and mtoa.mtd files before you start Maya. These two files are located under your MAYA_APP_DIR folder.

For example, C:\Users\SOLIDANGLE\Documents\maya\2013-x64\Maya.env.

MAYA_RENDER_DESC_PATH = C:\solidangle\mtoadeploy\2013.0.22.0
PATH = %PATH%;C:\solidangle\mtoadeploy\2013.0.22.0\bin

And C:\Users\SOLIDANGLE\Documents\maya\2013-x64\modules\mtoa.mod:

+ mtoa any C:\solidangle\mtoadeploy\2013.0.22.0

The mtoa.mod file is put there by the MtoA installer.

The MtoA installer always wants to remove any other installed version, so if you want to keep multiple versions around, you can do one of the following:

  • Extract the files yourself (for example, using 7zip)
  • Make copies of each MtoA version before you uninstall them.

For example, if you have MtoA 0.21 installed in 

C:\solidangle\mtoadeploy\2013

copy that folder to 

C:\solidangle\mtoadeploy\2013-0.21.0

Then install MtoA 0.22 (during the install, you may want to change the default install folder to something like C:\solidangle\mtoadeploy\2013-0.22.0).

After that, you’ll have both MtoA 0.22 and 0.21, and you can switch between them.

[MtoA] Editing Arnold attributes on multiple objects

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If you need to change the same Arnold attributes on many nodes, use the Attribute Spreadsheet. For example, suppose you wanted to turn off the Opaque attribute on a number of objects in your scene. Here’s how to do it:

  1. Select the objects.
  2. Press the Down arrow (aka Pick Walk) to select the shape nodes.
  3. Open the Attribute Spreadsheet.
  4. Click the All tab, and find the Ai (Arnold) attributes you want to change. Drag across all rows, and then type “off” in the last row.
    AiAttributeEditor

[SItoA] Doing a license check in Softimage

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Setting up the environment right is what often goes wrong. Running kick -licensecheck from inside Softimage is a quick way to check that you set up the environment variables correctly.

Here’s two lines of Python that will open a command prompt and run kick -licensecheck (on Windows).

#Python
from subprocess import Popen
Popen(["cmd", "/K", XSIUtils.BuildPath( Application.Plugins('Arnold Render').OriginPath, 'kick.exe' ), "-licensecheck"])

Here’s the same thing, but broken down a bit for legibility:

#Python
si = Application

p = si.Plugins('Arnold Render')
sKick = XSIUtils.BuildPath( p.OriginPath, 'kick.exe' )

from subprocess import Popen
Popen(["cmd", "/K", sKick, "-licensecheck"])

[MtoA] Doing a license check in Maya

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If you’re doing technical support like me, you gotta love things like kick -licensecheck. I wish we’d had something like this at Softimage. This license check will tell you:

  • Whether you can connect to a license server
  • What licenses are available
  • What are the licensing environment variable settings

licensecheck

In this example, I’m running Maya and the license server on the same computer. That’s why none of the environment variables are set, but the licensecheck still shows that there’s a license available. By default, Arnold will connect to 5053@localhost to get a license.