Updated the Gregory patch tessellation shaders to account for
transition edges.
Changed the implementation of OsdGetTessParameterizationTriangle()
to take the input parametric location as a 3-component value. This
allows the edge parameterization to be more numerically robust and
consistent.
Also, corrected some minor discrepancies between the various
tessellation shader configurations.
This matches the current GLSL implementation:
- BoxSplineTriangle and GregoryTriangle patch shaders
- tess factor and tess evalutation for triangle patches
- improved adaptive tessellation code organization and function names
- quartic Bezier triangle patch evaluation
- OsdGetPatchIsTriangleRotated() function added
- OsdInterpolatePatchCoordTriangle() function added
This change refactors the GLSL and HLSL patch shader code so that
most of the work is implemented within a library of common functions
and the remaining shader snippets just manage plumbing.
There is more to do here:
- varying and face-varying data can be managed entirely by the client
- similarly, displacement can be implemented in client code
- there's still quite a bit of residual boiler-plate code needed
in each shader stage that we should be able to wrap up in a more
convenient form.
Cleaned up the Legacy Gregory shader source by accessing buffer
data through helper functions.
Switched to performing tessellation in untransformed (object) space.
hlslPatchGregoryBasis.hlsl is an equivalent to glslPatchGregoryBasis.
Update dxViewer to be able to switch among bspline, gregorybasis, legacy
end capping.
also fixes a bug of GLSL legacy gregory shader which had an inconsistent
resource naming with example codes.
It looks like there's still an issue of D3D11 patchParam data fetching.
we'll come back to that bug.
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*().
computes edge lengths using limit surface points. Made this
the default screen-space metric so that we avoid cracks when
using Gregory Basis or Regular B-spline end caps.
The alternative method which computes edge lengths using the
distance between B-spline control points is still available.
Added a diagram and comments to explain how the control
points and limit points are organized.
- changed ptex layout data types in shaders to match srv format
- changed ptex srv type to unorm format for uchar data
- fixed hlsl compiler warning: initialized edgeDistance of OutputVertex struct in domain shader even if we are not in wireframe mode
- added directx debug device and enabled automatic break points to easily spot dx errors
Important notice: all client shader code must have following functions and compose them to osd intrinsic shaders (vertex/tessEval/tessControl)
mat4 OsdModelViewMatrix()
mat4 OsdProjectionMatrix()
mat4 OsdModelViewProjectionMatrix()
float OsdTessLevel()
int OsdGreogryQuadOffsetBase()
int OsdPrimitiveIdBase()
We probably should write a utility class for basic binding of them, to make client code simpler.
New text:
Copyright 2013 Pixar
Licensed under the Apache License, Version 2.0 (the "Apache License")
with the following modification; you may not use this file except in
compliance with the Apache License and the following modification to it:
Section 6. Trademarks. is deleted and replaced with:
6. Trademarks. This License does not grant permission to use the trade
names, trademarks, service marks, or product names of the Licensor
and its affiliates, except as required to comply with Section 4(c) of
the License and to reproduce the content of the NOTICE file.
You may obtain a copy of the Apache License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the Apache License with the above modification is
distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied. See the Apache License for the specific
language governing permissions and limitations under the Apache License.
- Added OSD_ prefix to preprocessor symbols
- Adjusted transition sub-patch parameterization to be
consistent with non-transition patches
- Unified BSpline shader code
- Removed duplicate Boundary, Corner, and Transition shader source
- Fixed a few discrepancies in the remaining duplicate code paths
