Demonstrating Free-hand Drawing of an Image using Polygons using GeoGebra
Drawing and Colouring the Pictures (Part 1)
You have already learnt how to draw images on computer desktop. You might have used mypaint, inkscape, colour paint, etc. to draw and paint the pictures. But, almost all images have mathematical concepts hidden in them. Therefore, we have another software GeoGebra with which we can also do such things.
Let us start doing thing.
Your computer desktop may be looking like this.
Opening GeoGebra:
Opening a file: To open a new file, double click on GeoGebra icon on your desktop.
If Icon of GeoGebra doesn’t appear on your desktop, you may follow another method. Go to Search bar icon---> click on it---->search bar appears
Type 'GeoGebra' in search bar-----> you will see 'GeoGebra' icon ---->click on 'GeoGebra' Icon
When you open the new file, it will look like as shown in Fig. 01.
Immediately after opening GeoGebra,
(Fig. 01)
it shows 'GeoGebra Math Apps' box (OR) 'Perspectives' box. By selecting 'Geometry', the Axes, which are appearing, will get disappeared. The other way to make these axes disappear is go to 'View' and uncheck 'Graphics'. Then, go to 'View' in the main menu and uncheck 'Algebra'.
The screen will look like this.
(Fig. 02)
Now our screen is ready to draw an image. What do you want to draw? Most of the times you try to draw an image of a house. Let us draw it and colour it.
Drawing a house:
Go to 'Toolbar', select 'Point' and click at the exact location which you desire.
A point will appear on the screen with name 'A'.
Then, select 'Polygon' in Toolbar as shown in the Fig. 03.
(Fig.03)
Now, click on the point A which we have plotted and draw a polygon by dragging and clicking at corners (vertices) as shown in the Fig. 04, 05, 06, 07 and 08.
(Fig. 04)
(Fig. 05)
(Fig. 06)
(Fig. 07)
(Fig. 08)
Now draw another parallelogram shaped diagram at one of the sides of the rectangle as shown in the Fig. 09, 10 and 11
(Fig. 09)
(Fig. 10)
(Fig. 11)
Now, you can draw a triangle on the top of the parallelogram, as shown in the Fig. 12 and 13.
(Fig. 12)
(Fig. 13)
Then, try to draw polygon like parallelogram, as shown in the Fig.14
(Fig. 14)
Finally complete the picture of a house by drawing doors and windows of it, as shown in the Fig. 15 or in the way as you think suitable.
(Fig. 15)
But, we have the picture of the house with all dots/points at the corners. We don't want these dots to appear.
For that, follow these steps:
Right click on the point, which you want to get disappeared. Then, it will look like Fig. 16. Now, uncheck 'Show object'. Thus we can hide the point.
(Fig. 16)
Similarly,
Hide all the points in the picture.
The final image of the house will be like this.
Colouring the house:
Now, let us colour the house which we have drawn.
To colour the front wall of the house:
Click on the polygon you want to colour. Then, a 'Graphics bar' appears below the toolbar as shown in the Fig. 17.
(Fig. 17)
Click on 'Colour' option in the graphics bar as shown in the Fig. 18.
(Fig. 18)
Then, options of different colours will appear as shown in the Fig. 19. Select any colour of your choice.
(Fig. 19)
Now, if you observe the picture, the borders only of the polygon are changed into your desired colour. Now, drag the pointer on the meter, as shown in the Fig. 20 to change the colour of the whole polygon.
(Fig. 20)
By changing the colour of the polygon, we can observe the colour of the front part of the house getting changed, as shown in the Fig. 21.
(Fig. 21)
Like this, you may try to change colours of the remaining polygons. You can see the final colouring of house as an example, as shown in Fig. 22.
(Fig. 22)
You can colour the house with the colours you desire.
Saving the file:
Now, we have to save our file.
To save our file, Press (Ctrl + s) or go to the main menu, then
select 'File'---->'Save'
Then, a box will appear with saving options as shown in the Fig. 23.
(Fig. 23)
Now select your desired location for saving this file, enter your file name in the box of 'File name' and click on 'Save'.
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