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The case of the disappearing particles
In this case, nParticles (render type = point) weren’t visible behind a refractive plane: For the points render type, you get an Arnold points shape (with mode “disk”), so I exported an ASS file to see...
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[MtoA] Finding your Arnold log file
When you enable file logging, it can seem a bit of a mystery where the .log files end up. You may find log files in different folders of your project, like the scenes folder, or the sourceimages...
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[MtoA] Normal mapping with mayaBump2d
mayaBump2D has an RGB parameter for normal maps, and it’s named “normal_map”: C:\solidangle\mtoadeploy\2015\bin>kick -l ..\shaders -info mayaBump2D node: mayaBump2D type: shader output: RGBA...
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[MtoA] Flushing the texture cache from Python
MtoA provides an arnoldFlushCache command (and the Arnold > Flush Caches menu uses that command). You can call it from Python like this: import maya.cmds as cmds cmds.arnoldFlushCache(...
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[MtoA] Instancing lights
If you want to instance lights in Maya, use Duplicate Special. MtoA will correctly translate those instances to Arnold (as copies, not instances, because Arnold itself doesn’t support light instances)....
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[MtoA] Is there an ARNOLD_PROCEDURAL_PATH environment variable?
No, there isn’t. HtoA recently added support for an ARNOLD_PROCEDURAL_PATH environment variable, but neither MtoA or Arnold itself support ARNOLD_PROCEDURAL_PATH. Here’s a few things you can do: If...
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[MtoA] MayaFile node uses a default color for missing textures
Here’s something important to remember when you’re debugging a scene… By default, the MayaFile node uses a default color if a texture is missing. This means the render won’t abort because of missing...
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[MtoA] Creating the defaultArnold nodes in scripting
Loading MtoA isn’t enough to create the defaultArnoldRenderOptions node. The defaultArnoldRenderOptions node isn’t created until a user opens the Arnold Render Settings for the first time. In code, you...
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[MtoA] Per-light AOVs for volumes
Arnold 4.2.12.2 added support for per-light AOVs for volumetrics. Here’s how to set up per-light AOVs in MtoA 1.2.6.0: In the light Attribute Editor, enter a name for the light group. Create a custom...
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WARNING mtoa_shading_groups: unresolved reference
Any time you see “node … is not installed” and “unresolved reference” warnings when you try to kick an ASS file exported from Maya, the problem is missing MtoA shaders. 00:00:00 18MB WARNING | [ass]...
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The case of the blue render view
Reason #35 why you should check the Arnold log In this case, a scene that used to render yesterday, now just resulted in a blue render view, like this: Anytime the render view doesn’t update when your...
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[MtoA] Adding per-face and per-vertex user data
With Maya and MtoA, there’s no easy way to add per-face and per-vertex user data attributes to objects. You’ve got to do it with scripting: add an array attribute with addAttr and then provide the...
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[MtoA] mtoa missing from Plug-in Manager
If mtoa.mll is not listed in the Plug-in Manager, that means that Maya did not find the MtoA module file (mtoa.mod). And if you try to manually load mtoa.mll, you’ll get errors like this: // Error:...
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[MtoA] Running a silent install on Windows
On Windows, if MtoA isn’t already installed, then the /S flag will do a silent install: MtoA-1.2.7.3-2016.exe /S You can also specify an install location with the /D flag: MtoA-1.2.7.1-2016.exe /S...
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[MtoA] The case of the missing mtoa.mll
I woke up this morning and my MtoA was gone😉 It turned out that mtoa.mll, ai.dll, and all the other DLLs were gone from the MtoA installation directory. How’d that happen? Probably when my computer had...
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[MtoA] Unable to dynamically load mtoa.mll …The specified procedure could not...
If the MtoA plug-in does not load and you get a “The specified procedure could not be found” error like this: // Error: line 1: Unable to dynamically load :...
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[MtoA] Switching between multiple versions of MtoA
If, like me, you need to switch between different versions of MtoA, here’s a recipe for setting that up. First, you have to install multiple versions. As you probably already know, the MtoA installer...
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Updating MtoA 1.2.7.3 with Arnold 4.2.14.0
MtoA 1.2.7.3 ships with Arnold 4.2.13. If you want to take advantage of the improvements in Arnold 4.2.14.0 (like the increase in the maximum number of threads from 128 to 256), here’s what you need...
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Exporting ASS files to specific locations
For the render -rt 1 command, you can specify the output ASS name in the defaultArnoldRenderOptions.output_ass_filename attribute. For example: set PRE_RENDER_MEL="setAttr -type \"string\"...
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Force Translate Shading Engines?
You may have noticed the Force Translate Shading Engine option in the export dialog (or in the Feature Overrides section of the Render Settings). Force Translate Shading Engines forces MtoA to export...
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