[Paraview] output->GetPointData()->SetScalars(pointScalars); No effect.

[Utkarsh Ayachit]

Please keep the discussion to the  mailing list.

What is the expected result here?


On Fri, Sep 13, 2013 at 11:06 AM, 庞庆源 <pangqingyuan1991 at gmail.com> wrote:

> Why this example can color the cube?
>
>
> 2013/9/13 庞庆源 <pangqingyuan1991 at gmail.com>
>
>> Thank you for your reply.I would like to show you a example and its
>> picture:
>>
>> /*=========================================================================
>>
>>   Program:   Visualization Toolkit
>>   Module:    Cube.cxx
>>
>>   Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
>>   All rights reserved.
>>   See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
>>
>>      This software is distributed WITHOUT ANY WARRANTY; without even
>>      the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
>>      PURPOSE.  See the above copyright notice for more information.
>>
>>
>> =========================================================================*/
>> // This example shows how to manually create vtkPolyData.
>>
>> #include "vtkActor.h"
>> #include "vtkCamera.h"
>> #include "vtkCellArray.h"
>> #include "vtkFloatArray.h"
>> #include "vtkPointData.h"
>> #include "vtkPoints.h"
>> #include "vtkPolyData.h"
>> #include "vtkPolyDataMapper.h"
>> #include "vtkRenderWindow.h"
>> #include "vtkRenderWindowInteractor.h"
>> #include "vtkRenderer.h"
>>
>> int main()
>> {
>>   int i;
>>   static float x[8][3]={{0,0,0}, {1,0,0}, {1,1,0}, {0,1,0},
>>                         {0,0,1}, {1,0,1}, {1,1,1}, {0,1,1}};
>>   static vtkIdType pts[6][4]={{0,1,2,3}, {4,5,6,7}, {0,1,5,4},
>>                         {1,2,6,5}, {2,3,7,6}, {3,0,4,7}};
>>
>>   // We'll create the building blocks of polydata including data
>> attributes.
>>   vtkPolyData *cube = vtkPolyData::New();
>>   vtkPoints *points = vtkPoints::New();
>>   vtkCellArray *polys = vtkCellArray::New();
>>   vtkFloatArray *scalars = vtkFloatArray::New();
>>
>>   // Load the point, cell, and data attributes.
>>   for (i=0; i<8; i++) points->InsertPoint(i,x[i]);
>>   for (i=0; i<6; i++) polys->InsertNextCell(4,pts[i]);
>>   for (i=0; i<8; i++) scalars->InsertTuple1(i,i);
>>
>>   // We now assign the pieces to the vtkPolyData.
>>   cube->SetPoints(points);
>>   points->Delete();
>>   cube->SetPolys(polys);
>>   polys->Delete();
>>   cube->GetPointData()->SetScalars(scalars);
>>   scalars->Delete();
>>
>>   // Now we'll look at it.
>>   vtkPolyDataMapper *cubeMapper = vtkPolyDataMapper::New();
>>       cubeMapper->SetInputData(cube);
>>       cubeMapper->SetScalarRange(0,7);
>>   vtkActor *cubeActor = vtkActor::New();
>>       cubeActor->SetMapper(cubeMapper);
>>
>>   // The usual rendering stuff.
>>   vtkCamera *camera = vtkCamera::New();
>>       camera->SetPosition(1,1,1);
>>       camera->SetFocalPoint(0,0,0);
>>
>>   vtkRenderer *renderer = vtkRenderer::New();
>>   vtkRenderWindow *renWin = vtkRenderWindow::New();
>>     renWin->AddRenderer(renderer);
>>
>>   vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
>>     iren->SetRenderWindow(renWin);
>>
>>   renderer->AddActor(cubeActor);
>>       renderer->SetActiveCamera(camera);
>>       renderer->ResetCamera();
>>       renderer->SetBackground(1,1,1);
>>
>>   renWin->SetSize(300,300);
>>
>>   // interact with data
>>   renWin->Render();
>>   iren->Start();
>>
>>   // Clean up
>>
>>   cube->Delete();
>>   cubeMapper->Delete();
>>   cubeActor->Delete();
>>   camera->Delete();
>>   renderer->Delete();
>>   renWin->Delete();
>>   iren->Delete();
>>
>>   return 0;
>> }
>> [image: 内嵌图片 1]
>>
>>
>> 2013/9/13 Utkarsh Ayachit <utkarsh.ayachit at kitware.com>
>>
>>> Float arrays cannot be directly mapped to colors. They need a LUT to
>>> convert to color. If you want to pass RGB colors, create a
>>> vtkUnsignedCharArray with 3 components instead. Then VTK can render
>>> those colors directly without mapping.
>>>
>>> On Fri, Sep 13, 2013 at 10:55 AM, 庞庆源 <pangqingyuan1991 at gmail.com>
>>> wrote:
>>> > scalararray is vtkFloatArray.I only call
>>> > pointScalars->InsertTuple1(myId,velocity) for every point.never call
>>> > SetNumberOfComponents();Is it the problem?
>>> >
>>> >
>>> > 2013/9/13 Utkarsh Ayachit <utkarsh.ayachit at kitware.com>
>>> >>
>>> >> WHat is the type of scalar array? If it's not an unsigned char array
>>> with
>>> >> 3 or 4 components, VTK will use a lookuptable to map the scalar to
>>> colors.
>>> >>
>>> >> Utkarsh
>>> >>
>>> >>
>>> >> On Fri, Sep 13, 2013 at 8:52 AM, 庞庆源 <pangqingyuan1991 at gmail.com>
>>> wrote:
>>> >>>
>>> >>>
>>> >>> I write a simple reader,inheriting from vtkPolyDataAlgorithm.But
>>> >>> SetScalars() cannot color the plane.When I test it use general vtk
>>> >>> polydata->mapper->actor->renderer->renderwindow,I can see different
>>> color at
>>> >>> different point.Does someone know the reason?Thank you.
>>> >>> --
>>> >>> 庞庆源
>>> >>>
>>> >>> _______________________________________________
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>>> >>>
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>>> >>> http://www.kitware.com/opensource/opensource.html
>>> >>>
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>>> >>> http://paraview.org/Wiki/ParaView
>>> >>>
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>>> >>>
>>> >>
>>> >
>>> >
>>> >
>>> > --
>>> > 庞庆源
>>>
>>
>>
>>
>> --
>> 庞庆源 <pangqingyuan1991 at gmail.com>
>>
>
>
>
> --
> 庞庆源 <pangqingyuan1991 at gmail.com>
>
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