# Fill area between lines with different colors

**URL:** https://discourse.vtk.org/t/fill-area-between-lines-with-different-colors/2681
**Category:** Support
**Created:** [February 22, 2020, 11:31pm UTC](https://discourse.vtk.org/t/fill-area-between-lines-with-different-colors/2681 "2020-02-22T23:31:00Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![kerim](https://discourse.vtk.org/user_avatar/discourse.vtk.org/kerim/32/1175_2.png) [@kerim](https://discourse.vtk.org/u/kerim)
#### Post date: [February 22, 2020, 11:31pm UTC](https://discourse.vtk.org/t/fill-area-between-lines-with-different-colors/2681/1 "2020-02-22T23:31:00Z")

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Hi,

Is there a way to plot line that has three dimensions **(x, y, z)** on two dimensional **XY** axes and fill the area between this line and some baseline (usually baseline is a constant value line) with color coded by **z** -values?  
In other words the line is represented by three vectors: **x** , **y** and **z**.  
Here is the example of it (2nd and 3rd plots): [https://www.mathworks.com/matlabcentral/mlc-downloads/downloads/submissions/38691/versions/2/screenshot.png](https://www.mathworks.com/matlabcentral/mlc-downloads/downloads/submissions/38691/versions/2/screenshot.png)

In Matlab it is done via patch() function [https://www.mathworks.com/help/matlab/ref/patch.html](https://www.mathworks.com/help/matlab/ref/patch.html)

Best regards

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<div class="post-metadata">

### Author: ![kerim](https://discourse.vtk.org/user_avatar/discourse.vtk.org/kerim/32/1175_2.png) [@kerim](https://discourse.vtk.org/u/kerim)
#### Post date: [February 24, 2020, 7:25pm UTC](https://discourse.vtk.org/t/fill-area-between-lines-with-different-colors/2681/2 "2020-02-24T19:25:09Z")

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Seems to me I have found a way to do this.  
I’m going to use **vtkPlotArea** from [example](https://lorensen.github.io/VTKExamples/site/Cxx/Plotting/AreaPlot/).  
The idea is to select the points that have the same color via virtual void [vtkPlot::SetSelection(vtkIdTypeArray \*id)](https://vtk.org/doc/nightly/html/classvtkPlot.html#aecbe4306a590789fb04144cbafd10c63) and apply [vtkPlot::GetSelectionBrush( )](https://vtk.org/doc/nightly/html/classvtkPlot.html#a065c0e18c75eb29c380045eb18cb687c) that should fill selected region with specified color.

The problem that it doesn’t work 🙃  
**I write the code:**  
/\* Color object \*/  
`vtkNew<vtkNamedColors> colors;`  
`vtkColor3d color3d = colors->GetColor3d("tomato");`

/\* Create area object \*/  
`vtkPlotArea* area = dynamic_cast<vtkPlotArea*>(chart->AddPlot(vtkChart::AREA)); // `

/\* select 10 first elements \*/  
` vtkNew<vtkIdTypeArray> arrSelect;`  
` arrSelect->SetName("Selection");`  
` arrSelect->InsertNextValue(0);`  
` arrSelect->InsertNextValue(1);`  
` arrSelect->InsertNextValue(2);`  
` arrSelect->InsertNextValue(3);`  
` arrSelect->InsertNextValue(4);`  
` arrSelect->InsertNextValue(5);`  
` arrSelect->InsertNextValue(6);`  
` arrSelect->InsertNextValue(7);`  
` arrSelect->InsertNextValue(8);`  
` arrSelect->InsertNextValue(9);`  
` area->SetSelection(arrSelect);`

/\* Fill selected area with specified color \*/  
`area->GetSelectionBrush()->SetColorF(color3d.GetRed(), color3d.GetGreen(), color3d.GetBlue(), .6);`

When I run the code the hole area is filled with black (i.e. colors didn’t work).

 ![image](https://discourse.vtk.org/uploads/default/original/2X/8/8d913d818c74cc802da4791bbbba64c9b33dbd65.png)  
If somebody has idea what do I do incorrect please give me a hint

Best regards