This examples is rewritten as a more comprehensive example
of Far and Osd APIs to generate batched index buffer and
vertex buffer, as well as sharing same topology and stencil
table among multiple objects.
Also this change includes an experimental code path of using
glMultiDrawElementsIndirect. It's currently incomplete due to
the missing interface of osd tessellation shader.
This restores the previous defaults and works around an
apparent runtime error on some platforms which is triggered
in the legacy gregory patch drawing code when patch culling
is disabled.
Remove DrawRegistry from osd layer and put a simple shader caching
utility into examples/common. osd layer only provides patch shader
snippet and let client configure and compile the code. Clients also
maintain the lifetime of shader object, which is preferable for the
actual application integration.
update all examples to use the new scheme.
These are now redundant since all bspline patches are encoded in
the patch tables consistently using 16 point indices with boundary
and corner edges indicated in the boundary mask of the patch params.
My earlier change which simplified the categorization of
patch types broke evaluation for boundary and corner patches.
Previously, boundary and corner patches were always rotated
into a canoncial orientation by permuting the point indices
of the patch. This was convenient in some cases, but generally
made things unecessarily complicated, since the parameterization
of the patch had to be counter-rotated to compensate.
Now patches always remain correctly oriented with respect
to the underlying surface topology and evaluation of boundary
and corner patches is accommodated by simply adjusting the
spline weights to account for the missing/invalid patch
points along boundary and corner edges.
There is more to clean up and optimize, but this restores
correct behavior.
Since unified shading work already removed subPatch info from
Osd::PatchDescriptor, the difference between Far::PatchDescriptor and
Osd::PatchDescriptor is just maxValence and numElements. They are used
for legacy gregory patch drawing.
Both maxValence and numElements are actually constant within a topology
(drawContext). This change move maxValence to DrawContext and let client
manage numElements, then we can eliminate Osd::PatchDescriptor and simply
use Far::PatchDescritor instead.
This is still an intermediate step toward further DrawRegistry refactoring.
For the time being, adding EffectDesc struct to include maxValence and
numValence to be maintained by the clients. They will be cleaned up later.
The side benefit of this change is we no longer need to recompile regular b-spline
shaders for the different max-valences.
- added Far::GetGregoryWeights() to work directly with 20 weights
- simplified tensor-product evaluation of Bezier and BSpline (will more
readily support higher order derivatives in near future)
- fixed Bezier derivative scaling issue (off by factor of 3.0)
* noted incorrectness of Gregory derivatives (correction will accompany
support for higher order derivatives in near future)
- Remove MeshPtexData bit from Osd::MeshBits. It's not used any more
- Rename ptexIndexBuffer in D3D11DrawContext to paramParamBuffer
- Remove Is/SetPtexEnabled from D3D11DrawRegistry
In OpenSubdiv 2.x, we encapsulated subdivision tables into
compute context in osd layer since those tables are order-dependent
and have to be applied in a certain manner. In 3.0, we adopted stencil
table based refinement. It's more simple and such an encapsulation is
no longer needed. Also 2.0 API has several ownership issues of GPU
kernel caching, and forces unnecessary instantiation of controllers
even though the cpu kernels typically don't need instances unlike GPU ones.
This change completely revisit osd client facing APIs. All contexts and
controllers were replaced with device-specific tables and evaluators.
While we can still use consistent API across various device backends,
unnecessary complexities have been removed. For example, cpu evaluator
is just a set of static functions and also there's no need to replicate
FarStencilTables to ComputeContext.
Also the new API delegates the ownership of compiled GPU kernels
to clients, for the better management of resources especially in multiple
GPU environment.
In addition to integrating ComputeController and EvalStencilController into
a single function Evaluator::EvalStencils(), EvalLimit API is also added
into Evaluator. This is working but still in progress, and we'll make a followup
change for the complete implementation.
-some naming convention changes:
GLSLTransformFeedback to GLXFBEvaluator
GLSLCompute to GLComputeEvaluator
-move LimitLocation struct into examples/glEvalLimit.
We're still discussing patch evaluation interface. Basically we'd like
to tease all ptex-specific parametrization out of far/osd layer.
TODO:
-implments EvalPatches() in the right way
-derivative evaluation API is still interim.
-VertexBufferDescriptor needs a better API to advance its location
-synchronization mechanism is not ideal (too global).
-OsdMesh class is hacky. need to fix it.
Changing all device kernels to take two buffer identifiers for
source and destination separately.
This change is an intermediate step toward upcoming context/controller
refactoring.
Previously we have a limitation that the source and destination
vertex buffer has to be a single buffer, since the subdivision
kernels are iteratively applied by level.
With stencil tables, we don't have such a limitation any more,
so we may want to apply stencils from seprate source buffer to
another.
To specifiy the output location within the destination buffer,
we can use VertexBufferDescriptor.offset. This allows us not only
configuring arbitrary batching scheme, but also relaxing the
limitation that source and destination buffers are in same
interleaved layout. For examples, we could include derivatives only
in the destination buffer, which doesn't need to be allocated in
the source buffer.
we're teasing out ptex specific data from core osd entities,
so there's no reason to keep ptex texturing utilities in core osd.
move them into example libs and let clients assemble shader snippets
as needed.
Also removing older ptex texturing code (without mipmap)
Each patch has a corresponding patchParam. This is a set of three values
specifying additional information about the patch:
faceId -- topological face identifier (e.g. Ptex FaceId)
bitfield -- refinement-level, non-quad, boundary, transition, uv-offset
sharpness -- crease sharpness for a single-crease patch
These are stored in OsdPatchParamBuffer indexed by the value returned
from OsdGetPatchIndex() which is a function of the current PrimitiveID
along with an optional client provided offset.
Accessors are provided to extract values from a patchParam. These are
all named OsdGetPatch*().
While drawing patches, the patchParam is condensed into a patchCoord which
has four values (u, v, faceLevel, faceId). These patchCoords are treated
as int values during per-prim processing but are converted to float values
during per-vertex processing where the values are interpolated.
Also, cleaned up more of the shader namespace by giving an Osd prefix
to public functions, and consolidated boundary and transition handling
code into the PatchCommon shader files. The functions determining
tessellation levels are now all named OsdGetTessLevel*().
