OSL Attribute node only works when SVM Attribute node is present #39415
Labels
No Label
Interest
Alembic
Interest
Animation & Rigging
Interest
Asset Browser
Interest
Asset Browser Project Overview
Interest
Audio
Interest
Automated Testing
Interest
Blender Asset Bundle
Interest
BlendFile
Interest
Collada
Interest
Compatibility
Interest
Compositing
Interest
Core
Interest
Cycles
Interest
Dependency Graph
Interest
Development Management
Interest
EEVEE
Interest
EEVEE & Viewport
Interest
Freestyle
Interest
Geometry Nodes
Interest
Grease Pencil
Interest
ID Management
Interest
Images & Movies
Interest
Import Export
Interest
Line Art
Interest
Masking
Interest
Metal
Interest
Modeling
Interest
Modifiers
Interest
Motion Tracking
Interest
Nodes & Physics
Interest
OpenGL
Interest
Overlay
Interest
Overrides
Interest
Performance
Interest
Physics
Interest
Pipeline, Assets & IO
Interest
Platforms, Builds & Tests
Interest
Python API
Interest
Render & Cycles
Interest
Render Pipeline
Interest
Sculpt, Paint & Texture
Interest
Text Editor
Interest
Translations
Interest
Triaging
Interest
Undo
Interest
USD
Interest
User Interface
Interest
UV Editing
Interest
VFX & Video
Interest
Video Sequencer
Interest
Virtual Reality
Interest
Vulkan
Interest
Wayland
Interest
Workbench
Legacy
Blender 2.8 Project
Legacy
Milestone 1: Basic, Local Asset Browser
Legacy
OpenGL Error
Meta
Good First Issue
Meta
Papercut
Meta
Retrospective
Meta
Security
Module
Animation & Rigging
Module
Core
Module
Development Management
Module
EEVEE & Viewport
Module
Grease Pencil
Module
Modeling
Module
Nodes & Physics
Module
Pipeline, Assets & IO
Module
Platforms, Builds & Tests
Module
Python API
Module
Render & Cycles
Module
Sculpt, Paint & Texture
Module
Triaging
Module
User Interface
Module
VFX & Video
Platform
FreeBSD
Platform
Linux
Platform
macOS
Platform
Windows
Priority
High
Priority
Low
Priority
Normal
Priority
Unbreak Now!
Status
Archived
Status
Confirmed
Status
Duplicate
Status
Needs Info from Developers
Status
Needs Information from User
Status
Needs Triage
Status
Resolved
Type
Bug
Type
Design
Type
Known Issue
Type
Patch
Type
Report
Type
To Do
No Milestone
No project
No Assignees
2 Participants
Notifications
Due Date
No due date set.
Dependencies
No dependencies set.
Reference: blender/blender#39415
Loading…
Reference in New Issue
No description provided.
Delete Branch "%!s(<nil>)"
Deleting a branch is permanent. Although the deleted branch may continue to exist for a short time before it actually gets removed, it CANNOT be undone in most cases. Continue?
System Information
Linux Mint 15, 64-bit
GeForce GTX 650
CPU: AMD FX-8320
Blender Version
Broken: 2.70
765d077
Short description of error
The OSL attribute node only works when the SVM Attribute node is present in the graph AND connected to another node (excluding Input and Output nodes)
Exact steps for others to reproduce the error
(Make sure to use CPU rendering, and Open Shading Language is checked on)
Using the default cube, add some Vertex Colors to it
blender/intern/cycles/kernel/shaders/osl_attribute.osl
For it to work, you'll need to do the following (after the above steps):
Add any node (could it be an Image Texture or a Math node, any node), but do not connect it to the others
Blendfile: getattribute.blend (Simply unplug the Attribute node, or change/erase the name in it)
Changed status to: 'Open'
Added subscriber: @kevindietrich
Added subscriber: @ThomasDinges
I just did a test and the same happens with the UV Map node (D230).
Changed status from 'Open' to: 'Archived'
Added subscriber: @LukasTonne
This is a known limitation of OSL in cycles: The way attributes work atm requires nodes to register which attributes they want to access in advance, when cycles starts syncing the scene but before shaders are compiled.
SVM nodes can do this because their attributes are either hardcoded or can be read from DNA data beforehand. This is not possible with OSL getattribute variants. Even though most of the time you'd use a string literal to define the attribute, it is also possible to use string parameters and dynamically constructed strings, which would require actual evaluation of the shader to determine the requested attribute.
The only feasible way to support this afaict is to have either explicit user-requested attributes associated to the node, or to implement lazy loading of attributes during the render process (unlikely this would work). Possibly it could be implemented using OSL metadata, which would directly associate the requests with the OSL code instead of placing it in the Blender DNA.
Putting this on the ToDo list: http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/ToDo
Quick mockup of how OSL metadata requests might work:
Ok then, thanks for the clarification.