OpenSubdiv/documentation/roadmap.rst

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Roadmap
-------

.. contents::
   :local:
   :backlinks: none

----

.. include:: under_development.rst

3.x Release Cycle
=================

For more details, please see the `Release Notes <release_notes.html>`_.

3.0 Alpha Releases (Q3 2014):

    * complete rewrite of the CPU subdivision core (collaboration with DWA)

        * new intermediate topology representation
        * new flexible topology front-ends
        * clarification of face-varying interpolation rules
        * support for non-manifold topology
        * large performance gains in topology analysis code
        * optimized adaptive isolation of edge creases
        * faster evaluation with stencil factorization
        * better numerical support around extraordinary vertices
        * support for Loop subdivision
        * deprecation of hierarchical edits
        * deprecation of subdivision tables

3.0 Beta Releases (Q4 2014 / Q1 2015):

    * subdivision 'specification' evaluation from users & community

        * implement API for direct discrete evaluation
        * support for bi-cubic face-varying interpolation (discrete & limit)
        * support for Loop limit evaluation

3.0 Master Release (Q1 2015)

    * freeze subdivision 'specification' (enforce backward compatibility)

To Infinity & Beyond
====================

The following is a list of projects and directions for OpenSubdiv over the course.

Optimize Draw
+++++++++++++
  OSD specializes topological patch configurations by configuring GPU shader
  source code. This causes back-end APIs to have to bind many shaders and
  burdens the drivers with many "draw" calls for each primitive, which does
  not scale well. Our goal is to ultimately try to reduce this burden back to
  a single shader bind per primitive.

    - Reduce GPU shader variants:

        + Merge regular / boundary / corner cases with vertex mirroring
        + Merge transition cases with degenerate patches
        + Merge rotations cases with run-time conditionals

  Note: this project has been started at Pixar.

Dynamic adaptive isolation
++++++++++++++++++++++++++

  Adaptive feature isolation can produce a large number of patches, especially
  when the model contains a lot of semi-sharp creases. We need a LOD solution
  that can dynamically isolate features based on distance to view-point.
  Note: this project has been undertaken by Matthias Niessner

Implement a "high-level" API layer
++++++++++++++++++++++++++++++++++

  One of the original goals of the OpenSubdiv project is to provide a robust
  and simple API to display subdivision surfaces interactively. Now that the
  algorithms and code base have matured, we would like to foster a consistent
  implementation of subdivision surfaces suitable for adoption in the lower
  layers of the graphics stack, such as GPU drivers. We have been working on
  the draft of a "specification document" detailing the workings of a high-
  level interface for subdivision surface data and functionality. We need an
  implementation of this high-level API.
  Note: this project has been started at Pixar.

Support for infinitely sharp creases
++++++++++++++++++++++++++++++++++++

  The current implementation of adaptive feature isolation requires infinitely
  sharp creases to be pushed to the highest level of isolation. The resulting
  surface is both incorrect and inefficient. We want to correctly support
  infinitely sharp creases with discontinuous patches that do not require to
  be isolated to the highest level of subdivision.

A means to control edge curvature
+++++++++++++++++++++++++++++++++

  Edge sharpness provides insufficient control over the overall contour of the
  surfaces. Artists often duplicate edge-loops around semi-sharp edges in
  order to control the local surface curvature. Ideally, they would like to be
  able to specify a radius of curvature that produces circular rounded edges.
  This will likely require the introduction of non-uniform rational splines
  (NURCCS ?) in OpenSubdiv.

"Next-gen" back-ends
++++++++++++++++++++

  Implement Osd::Draw Context & Controllers for next-gen GPU APIs such as
  Mantle, Metal, DX12, GL Next.

Regression testing
++++++++++++++++++

  OpenSubdiv currently ships with some ad-hoc regression code that unfortunately
  does not cover much of the code base: we need to implement a more rigorous QA
  process. We will probably want to leverage the CMake built-in functionalities
  of CTest in order to publish a build & test dashboard.

    * Implement a robust regression harness for numerical correctness
    * Implement a cross-platform regression harness for GPU drawing correctness
    * Implement a cross-platform regression harness for performance (speed & memory)

Documentation
+++++++++++++

  In order to facilitate adoption of OpenSubdiv, we need to provide clear,
  concise and exhaustive documentation of all APIs, and in particular:

    * Flesh out high-level ReST documentation
    * Expand code tutorials