[vtkusers] Rendering performance
Gib Bogle
g.bogle at auckland.ac.nz
Wed Nov 24 19:37:10 EST 2010
There is just one limitation (as far as I can see). One can't specify the glyph
colours individually. My spheres change colour as the state evolves. I'd like
to be able to control the square colours individually too, but that's less
important.
Cheers
Gib
On 25/11/2010 12:55 p.m., David Gobbi wrote:
> Hi Gib,
>
> Glad to hear the good news. I'm sure that you've also figured out that you can
> use glyphs for your spheres.
>
> Changing the number of glyphs is possible, but a bit tricky. You have to
> re-initialize the input polydata when changing the number of points or cells.
> So going back to my example code, you would do something like this:
>
> input->Initialize();
> input->SetPoints(new_points);
> input->SetVerts(new_verts);
>
> Generally you will have to re-build the points and the verts arrays from scratch
> if you want to remove elements. You can call Initialize() on the arrays to
> clear them before rebuilding them. The VTK arrays don't have an erase() method
> like C++ vectors do.
>
> David
>
>
> On Wed, Nov 24, 2010 at 4:34 PM, Gib Bogle <g.bogle at auckland.ac.nz
> <mailto:g.bogle at auckland.ac.nz>> wrote:
>
> Great success!! The glyphs render so fast that the extra time is
> negligible. Thanks again. It isn't needed for this application, but for
> future reference: is it possible to change the glypher input on the fly,
> i.e. the number of cells?
>
> Hi Fred, are you still interested in seeing the code that runs slowly?
>
>
> Gib
>
> On 25/11/2010 9:20 a.m., David Gobbi wrote:
>
> Hi Gib,
>
> Even though a programmable source like that wiki example is probably the
> "cleanest" way to do things, there is a simpler way to build a dataset for
> vtkGlyph3D.
>
> The vtkGlyph3D filter needs two inputs: one input for the positions of each
> glyph (i.e. one point per glyph) and another input for the glyph shape
> (i.e. the
> square that you already made).
>
> The first input is just a list of points, you can build it as a polydata
> just
> like you did with the squares, except that you want to use "verts" as
> your cells:
>
> vtkSmartPointer<vtkPoints> positions = vtkSmartPointer<vtkPoints>::New();
> vtkSmartPointer<vtkCellArray> dummycells =
> vtkSmartPointer<vtkCellArray>::New();
> positions->SetNumberOfPoints(npos); // number of squares
> dummycells->InsertNextCell(npos); // size of dummy "verts" array
> for (int ipos = 0; ipos < npos; ipos++)
> {
> positions->SetPoint(ipos, x, y, z); // square positions set here
> dummycells->InsertCellPoint(ipos);
> }
>
> vtkSmartPointer<vtkPolyData> input = vtkSmartPointer<vtkPolyData>::New();
> input->SetPoints(positions);
> input->SetVerts(dummycells);
>
> vtkSmartPointer<vtkGlyph3D> glypher = vtkSmartPointer<vtkGlyph3D>::New();
> glypher->SetInput(input);
> glypher->SetSource(polygonPolyData);
>
> Then feed the output of the glypher into the mapper, and it will
> automatically
> draw a square at each position. To change the positions, you would do this:
>
> positions->SetPoint(idx, x, y, z); // set point idx to (x,y,z)
> glypher->Modified(); // tell glypher that the data has changed
>
> Then re-render, and the squares will be at their new positions. I have not
> tested the code above, but I've done similar things in the past.
>
> David
>
> On Wed, Nov 24, 2010 at 12:52 PM, Gib Bogle <g.bogle at auckland.ac.nz
> <mailto:g.bogle at auckland.ac.nz>
> <mailto:g.bogle at auckland.ac.nz <mailto:g.bogle at auckland.ac.nz>>> wrote:
>
> Seb, if this is what you are referring to:
> http://www.itk.org/Wiki/VTK/Java_Code_Samples
> it might require skills a bit beyond my rather primitive level of
> C++ expertise.
>
>
> Gib
>
> Quoting Sebastien Jourdain <sebastien.jourdain at kitware.com
> <mailto:sebastien.jourdain at kitware.com>
> <mailto:sebastien.jourdain at kitware.com
> <mailto:sebastien.jourdain at kitware.com>>>:
>
>
> You can use a single actor, you will need to have a programable
> source
> that update the output dataset that has the location of each
> center of
> the square.
>
> Pipeline: Actor(Mapper(Glyph(CustomSource, Square)))
>
> To change the position of a square, you can have something like
> that...
>
> customSource.SetSquarePosition( suquareId, xyz )
>
> Seb
>
> PS: I think I wrote a sample code in Java for programmable
> source on the
> wiki...
>
>
> On Wed, Nov 24, 2010 at 1:41 PM, Gib Bogle
> <g.bogle at auckland.ac.nz <mailto:g.bogle at auckland.ac.nz>
> <mailto:g.bogle at auckland.ac.nz <mailto:g.bogle at auckland.ac.nz>>> wrote:
>
> Hi Seb,
>
> Although I referred to a simplified case in which the
> squares don't
> change,
> in general I need to allow for their movement. Therefore I
> don't
> think it
> will be possible for me to use a single actor. If I'm
> wrong, could you
> please provide a bit more detail?
>
> Thanks
> Gib
>
> Quoting Sebastien Jourdain <sebastien.jourdain at kitware.com
> <mailto:sebastien.jourdain at kitware.com>
> <mailto:sebastien.jourdain at kitware.com
> <mailto:sebastien.jourdain at kitware.com>>>:
>
>
> Hi Gib,
>
> My first question will be. Are you using one actor for
> each of your
> 10000 flat squares ?
> If so, the performance limitation may come from the
> number of actors
> involved. One solution to that is to create only one dataset
> with all
> the squares that has only one mapper and actor. To do
> so, you can
> build it by hand or simply use the Glyph filter with
> your square
> as a
> glyph and another dataset that has the location of those
> squares.
>
> Seb
>
>
> On Wed, Nov 24, 2010 at 12:44 AM, Gib Bogle
> <g.bogle at auckland.ac.nz <mailto:g.bogle at auckland.ac.nz>
> <mailto:g.bogle at auckland.ac.nz <mailto:g.bogle at auckland.ac.nz>>>
>
> wrote:
>
>
> I asked about this before, but didn't attract any
> responses.
> I have a
> better understanding of the issue now, so perhaps my
> questions will make
> more sense.
>
> At regular intervals as my simulation program
> executes, I am
> rendering a
> scene that contains mainly about 1000 small spheres
> (which
> move) and
> about
> 10000 flat squares (which do not move). I have
> discovered
> that the
> surprising slowness of the the rendering is caused
> by the
> squares, even
> though the spheres have ThetaResolution and
> PhiResolution
> both equal to
> 12,
> which I guess means 144 faces per sphere, i.e. a
> total of
> 144,000 faces.
> By
> my calculations rendering the scene 288 times with
> spheres
> alone takes
> about
> 4 sec, with the squares alone takes about 20 sec,
> and with
> both spheres
> and
> squares about 24 sec. That is, 10,000 squares take
> 5 times
> as long as
> 1000
> spheres with 144,000 faces.
>
> Apparently there's something very inefficient about
> the way I am
> rendering
> the squares. Here is the code for tileMapper (which
> makes
> squares):
>
> // Create the square
> // Setup points to draw a unit square in the XY
> plane, at y=0
> vtkSmartPointer<vtkPoints> points =
> vtkSmartPointer<vtkPoints>::New();
> vtkSmartPointer<vtkCellArray> vertices =
> vtkSmartPointer<vtkCellArray>::New();
> points->InsertNextPoint(-0.5, 0.0, -0.5);
> points->InsertNextPoint( 0.5, 0.0, -0.5);
> points->InsertNextPoint( 0.5, 0.0, 0.5);
> points->InsertNextPoint(-0.5, 0.0, 0.5);
>
> vtkSmartPointer<vtkPolygon> polygon =
> vtkSmartPointer<vtkPolygon>::New();
> polygon->GetPointIds()->SetNumberOfIds(4); //make a quad
> polygon->GetPointIds()->SetId(0, 0);
> polygon->GetPointIds()->SetId(1, 1);
> polygon->GetPointIds()->SetId(2, 2);
> polygon->GetPointIds()->SetId(3, 3);
>
> //Add the polygon to a list of polygons
> vtkSmartPointer<vtkCellArray> polygons =
> vtkSmartPointer<vtkCellArray>::New();
> polygons->InsertNextCell(polygon);
>
> //Create a PolyData
> vtkSmartPointer<vtkPolyData> polygonPolyData =
> vtkSmartPointer<vtkPolyData>::New();
> polygonPolyData->SetPoints(points);
> polygonPolyData->SetPolys(polygons);
>
> //Create a mapper and actor
> tileMapper = vtkPolyDataMapper::New();
> tileMapper->SetInput(polygonPolyData);
> tileMapper->ScalarVisibilityOff();
>
> The square actors are made like this:
>
> actor = vtkActor::New();
> actor->SetMapper(tileMapper);
> actor->GetProperty()->SetColor(boneColor);
> actor->GetProperty()->SetAmbient(0.5);
> actor->GetProperty()->SetDiffuse(0.2);
> actor->GetProperty()->SetSpecular(0.5);
> actor->SetPosition(pos);
> ren->AddActor(actor);
>
> then not touched again (in the simulations I report
> times for.)
>
> I'd be very grateful if someone could give me a clue
> as to
> what I'm doing
> wrong to make the rendering so slow.
>
> Thanks
> Gib
> _______________________________________________
> Powered by www.kitware.com <http://www.kitware.com>
> <http://www.kitware.com>
>
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
>
>
>
>
>
> ----------------------------------------------------------------
> This message was sent using IMP, the Internet Messaging Program.
> _______________________________________________
> Powered by www.kitware.com <http://www.kitware.com>
> <http://www.kitware.com>
>
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
>
>
>
>
>
> ----------------------------------------------------------------
> This message was sent using IMP, the Internet Messaging Program.
> _______________________________________________
> Powered by www.kitware.com <http://www.kitware.com>
> <http://www.kitware.com>
>
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
>
>
> _______________________________________________
> Powered by www.kitware.com <http://www.kitware.com>
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
>
>
More information about the vtkusers
mailing list