AuroraMiddleware/OpenSubdiv
1
0
Fork 0
mirror of https://github.com/PixarAnimationStudios/OpenSubdiv synced 2024-11-24 12:30:17 +00:00
Code Issues Releases Wiki Activity

Update subdivision ReST documentation to match changes in Sdc

Browse Source
This commit is contained in:
manuelk 2014-12-18 11:14:19 -08:00
parent 4643a51fb0
commit 5214a6d2ab
6 changed files with 89 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

BIN
documentation/diagrams.odg
View File

Binary file not shown.

BIN
documentation/images/chaikin.png
View File

Binary file not shown.
Side by Side Swipe Overlay

Before

Width:  |  Height:  |  Size: 36 KiB

After

Width:  |  Height:  |  Size: 33 KiB

BIN
documentation/images/fvar_boundaries.png
View File

Binary file not shown.
Side by Side Swipe Overlay

Before

Width:  |  Height:  |  Size: 66 KiB

After

Width:  |  Height:  |  Size: 57 KiB

BIN
documentation/images/smoothtriangles.png Normal file
View File

Binary file not shown.
Side by Side

After

Width:  |  Height:  |  Size: 316 KiB

BIN
documentation/images/vertex_boundary.png
View File

Binary file not shown.
Side by Side Swipe Overlay

Before

Width:  |  Height:  |  Size: 12 KiB

After

Width:  |  Height:  |  Size: 13 KiB

132
documentation/subdivision_surfaces.rst
View File

@ -126,6 +126,17 @@ This case is fairly trivial: there is no possible way to exact a limit surface
here, so the vertex simply has to be flagged as non-contributing, or discarded
gracefully.
.. container:: notebox
**Beta Issues**
As of 3.0.0 Beta release, support for non-manifold topology is not available
yet. The topology factories are currently set to report warnings when
non-manifold configurations are encountered and implicitly treat them as
sharp boundaries. We intend to fully specify and implement a set of
of interpolation rules in a future release of OpenSubdiv.
----
Boundary Interpolation Rules
@ -139,20 +150,19 @@ Vertex Data
The following rule sets can be applied to vertex data interpolation:
+------------------------+----------------------------------------------------------+
| Mode | Behavior |
+========================+==========================================================+
| 0 - **None** | No boundary interpolation behavior should occur |
| | (debug mode - boundaries are undefined) |
+------------------------+----------------------------------------------------------+
| 1 - **EdgeAndCorner** | All the boundary edge-chains are sharp creases and |
| | boundary vertices with exactly two incident edges are |
| | sharp corners |
+------------------------+----------------------------------------------------------+
| 2 - **EdgeOnly** | All the boundary edge-chains are sharp creases; boundary |
| | vertices are not affected |
| | |
+------------------------+----------------------------------------------------------+
+----------------------------------+----------------------------------------------------------+
| Mode | Behavior |
+==================================+==========================================================+
| **VTX_BOUNDARY_NONE** | No boundary interpolation behavior should occur |
| | (debug mode - boundaries are undefined) |
+----------------------------------+----------------------------------------------------------+
| **VTX_BOUNDARY_EDGE_ONLY** | All the boundary edge-chains are sharp creases and |
| | boundary vertices with exactly two incident edges are |
| | sharp corners |
+----------------------------------+----------------------------------------------------------+
| **VTX_BOUNDARY_EDGE_AND_CORNER** | All the boundary edge-chains are sharp creases; boundary |
| | vertices are not affected |
+----------------------------------+----------------------------------------------------------+
On a quad example:
@ -166,26 +176,21 @@ Face-varying Data
The following rule sets can be applied to face-varying data interpolation:
+--------+----------------------------------------------------------+
| Mode | Behavior |
+========+==========================================================+
| 0 | Bi-linear interpolation (no smoothing) |
+--------+----------------------------------------------------------+
| 1 | Smooth UV |
| | |
| | |
+--------+----------------------------------------------------------+
| 2 | Same as (1) but does not infer the presence of corners |
| | where two face-varying edges meet at a single faceA |
| | |
+--------+----------------------------------------------------------+
| 3 | Smooth face-varying values only near vertices that are |
| | not at a discontinuous boundary; all vertices on a |
| | discontinuous boundary are subdivided with a sharp rule |
| | (interpolated through). |
| | This mode is designed to be compatible with ZBrush and |
| | Maya's "smooth internal only" interpolation. |
+--------+----------------------------------------------------------+
+--------------------------------+------------------------------------------+
| Mode | Behavior |
+================================+==========================================+
| **FVAR_LINEAR_NONE** | smooth everywhere ("edge only") |
+--------------------------------+------------------------------------------+
| **FVAR_LINEAR_CORNERS_ONLY** | sharpen corners only |
+--------------------------------+------------------------------------------+
| **FVAR_LINEAR_CORNERS_PLUS1** | "edge corner" |
+--------------------------------+------------------------------------------+
| **FVAR_LINEAR_CORNERS_PLUS2** | "edge and corner" + "propagate corner" |
+--------------------------------+------------------------------------------+
| **FVAR_LINEAR_BOUNDARIES** | sharpen all boundaries ("always sharp") |
+--------------------------------+------------------------------------------+
| **FVAR_LINEAR_ALL** | bilinear interpolation ("bilinear") |
+--------------------------------+------------------------------------------+
Unwrapped cube example:
@ -199,6 +204,34 @@ Propagate Corners
Face-varying interpolation mode 2 (*EdgeAndCorner*) can further be modified by
the application of the *Propagate Corner* flag.
----
"Triangle Subdivision" Rule
===========================
The triangle subdivision rule is a rule added to the Catmull-Clark scheme that
can be applied to all triangular faces; this rule was empirically determined to
make triangles subdivide more smoothly. However, this rule breaks the nice
property that two separate meshes can be joined seamlessly by overlapping their
boundaries; i.e. when there are triangles at either boundary, it is impossible
to join the meshes seamlessly
+---------------------+---------------------------------------------+
| Mode | Behavior |
+=====================+=============================================+
| **TRI_SUB_CATMARK** | Default Catmark scheme weights |
+---------------------+---------------------------------------------+
| **TRI_SUB_SMOOTH** | "Smooth triangle" weights |
+---------------------+---------------------------------------------+
Cylinder example :
.. image:: images/smoothtriangles.png
:align: center
:height: 300
:target: images/smoothtriangles.png
----
Semi-Sharp Creases
@ -237,6 +270,16 @@ Chaikin's curve subdivision algorithm improves the appearance of multi-edge
semi-sharp creases with varying weights. The Chaikin rule interpolates the
sharpness of incident edges.
+---------------------+---------------------------------------------+
| Mode | Behavior |
+=====================+=============================================+
| **CREASE_UNIFORM** | Apply regular semi-sharp crease rules |
+---------------------+---------------------------------------------+
| **CREASE_CHAIKIN** | Apply "Chaikin" semi-sharp crease rules |
+---------------------+---------------------------------------------+
Example of contiguous semi-sharp creases interpolation:
.. image:: images/chaikin.png
:align: center
:target: images/chaikin.png
@ -269,6 +312,18 @@ of detail.
----
.. container:: notebox
**Release Notes (3.0.0)**
Hierarchical Edits have been marked as "extended specification" and support for
hierarchical features has been removed from the 3.0 release. This decision
allows for great simplifications of many areas of the subdivision algorithms.
If we can identify legitimate use-cases for hierarchical tags, we will consider
re-implementing them in future releases, as time and resources allow.
----
Hierarchical Edits Paths
************************
@ -380,15 +435,6 @@ Modifiable properties include:
:height: 300
:target: images/hedit_example5.png
----
Limitations
***********
.. include:: under_development.rst
----
Uniform Subdivision