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This page will describe the steps to make a simple pie chart, with instructions on upfront circle creation, mouse-overs, statistic analysis, and user-sectioning.
Circles in General
Mathematical Functions are important while using geometry or math in general on Scratch. This page will cover the various formulas needed in Scratch, while also going over the circle and ellipse formulas in sections 2.3 and 2.3.1.
In this section:
- pi is the value of Pi (3.14159...)
- r is the radius of the circle
This will calculate the area of a circle:
((pi) * ((r) * (r))) // pi * r squared
and this will calculate the circumference of a circle:
((2) * ((pi) * (r)))
Pi can be hard to define, so some users like to approximate it to 3.1415926535 or calculate it using atan.
Techniques to Stand Out
Up-front Creation
In this case, the user will be able to see the graph be created in front of them. A unique relationship is that the smaller the turn angle, the bolder the graph will look. However, the smaller the turn angle is, the greater the generation time will be.
repeat ((360) / (turn radius)) go to x: (0) y: (0) pen down move (radii) steps go to x: (0) y: (0) turn right (turn radius) degrees
Where:
- Radii is the radius of the circle
- Turn Radius is how many degrees are in each turn
Mouseovers
This script makes text display and play a sound when the mouse is hovered over a portion of the pie chart.
First create this simple code:
when flag clicked hide
when [space v] key pressed show forever go to [mouse-pointer v] end
This will make a given icon follow the mouse-pointer.
when flag clicked forever if <touching color [#FF0000]?> then repeat until < <touching color [#F3A533]> or <touching color [#FFFFFF]> > say [Section 1] for (1) secs // change this depending on how long the message should be displayed play sound [pop v] // optional end end end