[vtk-developers] Some OpenGL2 Polygonal Updates etc

Ken Martin ken.martin at kitware.com
Mon Feb 2 11:26:24 EST 2015

Here are a few updates to the polygonal work we’ve been doing on the new
OpenGL2 backend in VTK.

1)      Created a vtkPointGaussianMapper [3] class for cosmology for
quickly rendering lots of translucent Gaussian splats.  This class will get
refined a bit as it starts getting used more. Similar in concept to the
PointSprite extensions that were added into Paraview by John Biddiscombe,
Ugo Varetto and Stephane Ploix from CSCS and EDF.

2)      Changed how the transformation matrices were handled in the vertex
shader [7]. It was doing V’ = VCDC * MCVC * V  and a couple tests were
failing. Instead we now compute MCDC on the CPU in double precision and
instead do V’ = MCDC * V in the shader which fixed the test and is
generally a better way to do it. We often need the other two matrices as
well which is why the original code just used those.

3)      Added a rendering timing framework/executable [5] to make it easier
to run test sequences across machines and see the results. Marcus and Rob
have expanded on it and Aashish has added a volume rendering test.

4)      Rewrote the vtkParametricFunctionSource [6] to be significantly
faster (4x) and more memory efficient.  We use this source to generate
surfaces for rendering timings and it was a bit slow.

5)      A bunch of fixes related to getting IceT to work with OpenGL2 [1]
which led to some release graphics resource issues being fixed [2].

6)      “Fixed” a longstanding failing test, TestChartXYZ [4] which was
intermittently failing on some systems.

7)      Marcus and Rob ran some rendering benchmarks showing upwards of 3
billion triangles per second on a 300 million triangle model. That is a big
model and some solid performance.

Currently I am wrapping up a change to the vtkCompositePolyDataMapper2 so
that in some common circumstances it will render significantly faster
(maybe 10x). This is targeted at helping apps that have lots of small
polygonal parts that are not glyphed. Also adding in support for texture
coordinate transformation matrices which are used by the GeoView classes in
VTK. Tim Thirion is fixing up some iOS build issues and David Lonnie is
working on removing an old text mapper that was causing some issues. JC has
been working on updating Slicer to build against the current VTK with



[1] http://review.source.kitware.com/#/t/5130/

[2] http://review.source.kitware.com/#/t/5171/

[3] http://review.source.kitware.com/#/t/5198/

[4] http://review.source.kitware.com/#/t/5248/

[5] http://review.source.kitware.com/#/t/5276/

[6] http://review.source.kitware.com/#/t/5302/

[7] http://review.source.kitware.com/#/t/5327/

Ken Martin PhD

Chairman & CFO

Kitware Inc.

28 Corporate Drive

Clifton Park NY 12065

ken.martin at kitware.com

518 881-4901 (w)

518 371-4573 (f)

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