A bit work in progress, currently the following limitations:
- Texture shading only, Material shading will come later
- No UVs subdivision yet
- Always uses active UV and currently changing active UV will
not properly update the viewport.
Well, need to start somewhere :)
This is really similar to what GPU module was already doing. There are number of
possible improvements still:
- Re-use allocated VAOs when requesting new ones instead of going to the trouble
of freeing VAO and then re-creating it again.
- Move VAO handling to GPU module.
Fixes T46589: OpenSubdiv crash with drivers
The issue was caused by CCG code being confused by number of geometry returned
by utility functions in the case of the skipped grids.
Made it so that code is always only working with CCG data and handled drawing
code in a bit special way now.
This solves such crashes as i.e. snapping.
This commit contains all the remained parts needed for initial integration of
OpenSubdiv into Blender's subdivision surface code. Includes both GPU and CPU
backends which works in the following way:
- When SubSurf modifier is the last in the modifiers stack then GPU pipeline
of OpenSubdiv is used, making viewport performance as fast as possible.
This also requires graphscard with GLSL 1.5 support. If this requirement is
not met, then no GPU pipeline is used at all.
- If SubSurf is not a last modifier or if DerivesMesh is being evaluated for
rendering then CPU limit evaluation API from OpenSubdiv is used. This only
replaces the legacy evaluation code from CCGSubSurf_legacy, but keeps CCG
structures exactly the same as they used to be for ages now.
This integration is fully covered with ifdef and not enabled by default
because there are several TODOs to be solved first:
- Face varying data interpolation is not really cleanly implemented for GPU
in OpenSubdiv 3.0. It is also not implemented for limit evaluation API.
This basically means we'll have really hard time supporting UVs.
- Limit evaluation only works with adaptivly subdivided meshes so far, which
basically means all the points of CCG are pushed to the limit. This gives
different result from old code.
- There are some serious optimizations possible on the topology refiner
creation, which would speed up initial OpenSubdiv mesh creation.
- There are some hardcoded asumptions in the GPU and DerivedMesh areas which
could be generalized.
That's something where Antony and Campbell can help, making it so the code
is structured in a way which is reusable by all planned viewport projects.
- There are also some workarounds in the dependency graph to make sure OpenGL
buffers are only freed from the main thread.
Those who'll be wanting to make experiments with this code should grab dev
branch (NOT master) from
https://github.com/Nazg-Gul/OpenSubdiv/tree/dev
There are some patches applied in there which we're working on on getting
into upstream.
This is a preparation commit for having OpenSubdiv integrated into Blender
and new layout is the following:
- CCGSubSurf.c contains implementation of common functions used by both
legacy subdivisions code and by the new code in the future.
- CCGSubSurf_inline.h contains internal functions which are to be inlined
due to the performance reasons. Those functions are only ment to be used
bu CCGSubSurf* files.
- CCGSubSurf_intern.h contains declarations of private functions and data
structures used by CCGSubSurf module.
- CCGSubSurf_legacy.c contains legacy implementation of subdivision algorithm.
- CCHSubSurf_util.c contains utility functions which are not directly related
on the subdivision code (i.e. debug functions, hash implementation etc).
There should be no functional changes so far.
