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minor update in osd_overview.

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Takahito Tejima 2015-06-22 13:26:01 -07:00
parent 0950d7e449
commit 8dfbbe1f3b
1 changed files with 18 additions and 12 deletions
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documentation/osd_overview.rst
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@ -54,11 +54,15 @@ The main roles of **Osd** are:
Provide convenient classes to interop between compute and draw APIs
These are independently used by clients. For example, a client can use only
the stencil table evaluation. A client can call **Osd** compute functions
on its own vertex buffers.
the limit stencil evaluation, or a client can refine subdivision surfaces
and draw them with the PatchTable and **Osd** tessellation shaders.
All device specific evaluation kernels are implemented in the Evaluator classes.
Since Evaluators don't own vertex buffers, clients should provide their own
buffers as a source and destination. There are some interop classes defined
in **Osd** for convenience.
OpenSubdiv enforces the same results for the different computation backends with
a series of regression tests that compare the methods to each other.
OpenSubdiv utilizes a series of regression tests to compare and enforce
identical results across different computational devices.
----
@ -103,9 +107,10 @@ as a stencil tables as long as Evaluator::EvalStencils() can access the necessar
Limit Stencil Evaluation
========================
Limit stencil evaluation is quite similar to refinement in **Osd**. Clients
create Far::LimitStencilTable for the locations need to evaluate. Then create
an evaluator compatible stencil table and call Evaluator::EvalStencils().
Limit stencil evaluation is quite similar to refinement in **Osd**. At first
clients create Far::LimitStencilTable for the locations to evaluate the limit
surfaces, then convert it into an evaluator compatible stencil table and call
Evaluator::EvalStencils().
.. image:: images/osd_limitstencil.png
:align: center
@ -113,8 +118,9 @@ an evaluator compatible stencil table and call Evaluator::EvalStencils().
Limit Evaluation with PatchTable
================================
In **Osd**, the limit surfaces can also be evaluated by PatchTable once all
control vertices and local points are resolved by the stencil evaluation.
Another way to evaluate the limit surfaces is to use the PatchTable.
Once all control vertices and local points are resolved by the stencil evaluation,
**Osd** can evaluate the limit surfaces through the PatchTable.
.. image:: images/osd_limiteval.png
:align: center
@ -203,9 +209,9 @@ BufferDescriptor can be used for an interleaved buffer too.
Osd::BufferDescriptor xyzDesc(0, 3, 7);
Osd::BufferDescriptor rgbaDesc(3, 4, 7);
Although the source and the destination buffer don't have to be a same buffer for
EvalStencils(), adaptive patch tables are constructed to index the coarse vertices
first and immediately followed by the refined vertices. In this case, the
Although the source and destination buffers don't need to be the same buffer for
EvalStencils(), adaptive patch tables are constructed to first index the coarse
vertices and the refined vertices immediately afterward. In this case, the
BufferDescriptor for the destination should include the offset as the number of coarse
vertices to be skipped.