Personal Information:

• Name: Korlam Gautam
• E-mail address: korlamgautam@gmail.com 
• IRC nick: kageiit, Server: irc.freenode.net
• Jabber: kageiit@gmail.com

Idea to implement:

Synopsis and Goals:

Synopsis: To Design a Nodes editor for materials and textures. 

Why: Most 3D suites presently have some form of support for using node based materials and textures to create complex materials. Yafaray's interface in Blender does not have its own Material and texture node editor and this makes it difficult to create advanced materials for use with Yafaray using the simple editor for materials. Thus, there is a need to for a node based material and texture system in Yafaray and a node editor to accomplish the job.

Goals: To develop a new node based material system for Yafaray. To have a separate nodes editor with a smooth work flow and ease of use  similar to the one available in the native blender UI along with some advanced features. The editor can be started from within Yafaray and would function as an external component. 

Benefits:

• This would benefit Yafaray by allowing users to access more complex and wider range of materials and a greater power over how their final renders look. 
• Such a useful and intuitive feature would greatly increase Yafaray user base and motivate artists to use Yafaray for more complex jobs. 
• Another advantage would be that the editor will function as a useful tool even if Yafaray is used with other 3D suites by not relying on the suite's set of features for material and texture creation using nodes explicitly. 

Deliverables: 

1. Source code for the final editor program
2. Source code for the new node based materials and their data structure specifications, an API reference to add new node types.
3. Non-Code deliverables include testing performed at various phases to verify the correctness of the code and features implemented in general. Also detailed user and development documentation for using the editor will be added. If time permits a set of test cases will be added. 

Detailed Description:

Coding: I plan to develop the editor interface including most of the features of the blender's native editor, without having to rely on blender in anyway. This would ensure the editor to work out of the box with its only dependency being the Yafaray library, which makes it reusable with any other 3D suite along with Yafaray. I plan to use C++ and Qt libraries for developing the editor. Qt is cross platform and even runs on embedded OS like Symbian, Maemo etc. The code will be flexible enough to incorporate new changes later on if needed like integration of Sub-Surface Scattering, OSL etc.

Features to be implemented:

• A node based material system. For creation of complex materials. An API to integrate new features and node types easily.
• Intuitive Editor user interface. To provide smooth workflow similar to the node editor in blender.
• Utilities like customizable keyboard shortcuts, automatic layout of nodes in editor to enhance user experience, cater to advanced users and increase productivity.
• Custom importer/exporter plugin for materials, independent of the Yafaray XML Scene files. To allow users to create material libraries for easy distribution and sharing.
• An importer function to import from an online repository of material libraries where users can share libraries and so that commonly used node based materials are easily available with just a few clicks.

About Nodes: There will be three types of basic nodes. They are:

1. Input/Output – Material, Texture, Geometry, Color etc.
2. Mixer – Color Mixer, Add Component etc.
3. BSDF – Lambert, Diffuse etc.

Other types of nodes such as group nodes are provided for convenience in work flow. Each node will also have a small area for previewing the result until that point, when available.

For example, to create a matte yellow material could be as simple as compositing material -> Lambert BSDF (color set to yellow).

Changes in Yafaray: The node based material will be one single extra material. The new material will contain all the properties necessary for its implementation, being in the xml file or being the Yafaray structures themselves. It will also contain meta information regarding placement and size of nodes in editor, any node group they belong to etc. The old materials in Yafaray such as glass, shinydiffuse will still be available and usable. Users who wish to work with simple materials may choose not use nodes. For complex materials, users can choose to create a new material using nodes. So the Yafaray XML specification is extended to include the new node based materials and old materials are not affected consequently.

Structure of node based materials:

Each node based material will be represented as a nodes graph where the output node is at the root, the constituting nodes go down the hierarchy till we reach leaf nodes i.e input nodes. This is shown in the following schematic:

The node graph can be stored as a complex network of nodes which can be represented by using a data structure such as adjacency list. This can be stored in the XML in the form of root node, list of child node ids, each child node further having its own children. To avoid repetition each unique node is stored once and the id is used to reference it for any node which uses it as a child.

For example, for the above shown network, the structure would be like:

• root->[ramp_node_id,mix_node_id]
• ramp_node->[simple_material_node_id]
• mix_node->[rgba_node_id,simple_material_node_id,Lambert_bsdf_node_id]

Integration with Yafaray: The editor would fetch the required data structures for materials/textures from Yafaray, allow the user to make changes using the editor UI and send the processed data back to Yafaray, i.e Yafaray performs the parsing of XML and the final saving to XML, the editor acts as an intermediary to add new materials, make changes to existing materials etc. this allows for a more flexible design from Yafaray's point of view.

Work Flow and Usability:

Work flow: The interface will be very similar to blender's node editor interface. Most common actions available in the blender editor will be implemented with customizable keyboard shortcuts for all actions such as duplicating a node, making groups of nodes etc. Node connections are made similar to blender in an intuitive fashion. Optionally, a feature to automatically organize nodes neatly on the screen when there are too many nodes will be available (if time permits).

Usability: The user can create materials from scratch or apply a set of operations on materials already imported to Yafaray from blender. The user will be presented with a preview of the material/texture at each step when possible. Common operations such as zooming in/out, moving nodes etc. will be available to the user.

A Typical Usage Scenario:

• User launches the Yafaray export plugin (not necessarily in blender)
• User chooses to create a new node based material, clicks the node editor button in the Yafaray interface
• Editor inherits any existing materials from the exporter plugin. Now user may start working with such inherited materials, materials imported from external material library file, online material repository or start with new material nodes
• User makes changes to material, viewing progress in the preview panels. User may save existing materials to external file or export back to Yafaray or both
• Once the user is back in the Yafaray UI, the new node-based materials will be available in the material selection dialog. To edit such node based materials, user needs to relaunch the editor
• Finally, user may render or export to Yafaray XML as usual

A rough initial view of the editor:

Tentative Schedule:

The project is realizable within a period of 3-4 months. The project is planned to be completed in 8 phases. Every phase includes documenting the progress during that phase. The timeline for each of these phases is given below:

Note: I shall not be available from July 16th to July 21st as I have to enroll in my university for a new semester, choose subjects etc. I apologize for it.

To get a better visual picture of the timeline you may visit [1].