Example 1: Drawing Curves

     This example is also available on YouTube.

Introduction

In this example, you will draw one or more curves into a diagram and define different styles for the curves.

Steps to Do

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A curve requires x- and y-coordinates to be printed. You can use the CurveCreator module as input for these coordinates. The SoDiagram2D draws the curves into a SoRenderArea. You can also define the style of the curves by using the StylePalette module.

Add the modules to your workspace and connect them as seen below.

Creating a Curve

Click on the output of the CurveCreator module and open the Output Inspector.

Double-click on the CurveCreator module and open the panel.

You can see a large input field Curve Table. Here, you can enter the x- and y-values of your curve. The values of the first column will become the x-values and the second column will become the y-series. Comment lines start with a ‘#’ character.

Enter the following into the Curve Table:

# My first curve
0 0
1 1
2 2
3 3
4 4
5 5
10 10
50 50

Now, your Output Inspector shows a yellow line through the previously entered coordinates. Exactly the same curve is shown in the SoRenderArea.

Creating Multiple Curves

Now, update the Curve Table, so that you are using three columns and click Update :

# My first curves
0 0 0
1 1 2
2 2 4
3 3 6
4 4 8
5 5 10
10 10 20
50 50 100

You can see two curves. The second and third columns are printed as separate curves. Both appear yellow. After checking Split columns into data sets, you will see one yellow and one red curve.

If the flag Split columns into data sets is set to TRUE, then a table with more than two columns is split into different CurveData objects. This gives the user the possibility to assign a different style and title for each series.

Titles and Styles

Let’s do this. Open the panel of the SoDiagram2D module and check Draw legend. Enter “Curve1 Curve2” into the Title(s) text box of the CurveCreator module and click Update .

You can also define a different location of the legend and set font sizes.

Now, open the panel of the StylePalette module.

The StylePalette module allows you to define twelve different styles for curves. Initially, without manual changes, the styles are applied one after the other. The first curve gets style 1, the second curve style 2, and so on.

Open the panel of your CurveCreator module again and define Curve Style(s) as “3 6”. Update your curves.

You now applied the style three for your first curve and style six for the second. This is how you can create twelve different curves with a unique appearance each.

Using Multiple Tables for Curve Generation

In addition to adding multiple columns for different y-coordinates, you can also define multiple tables as input, so that you can also have different x-coordinates for multiple curves.

Update the Curve Table as defined below and click Update :

# My first curves
0 0 0
1 1 2
2 2 4
3 3 6
4 4 8
5 5 10
10 10 20
50 50 100
---
# My third curve
0 0
1 1
2 4
3 9
4 16
5 25
6 36
7 49
8 64
9 81
10 100

Also add another title to your curves and define a third style.

Summary

• Curves can be created to draw two-dimensional diagrams.
• The StylePalette module allows you to define the appearance of a curve.
• Details of the different curves can be visualized by using the SoDiagram2D module.

   Download .mlab file here.