Corona SDK Tutorial: Circle Objects

Make a Circle

To make a circle in Corona SDK we use the function newCircle of the display object. This function takes three parameters in this order.:

• the x coordinate for the center
• the y coordinate for the center
• the circle’s radius

config.lua

First let’s make a config file to set the screen size.

application =
{
     content =
     {
        width = 320,
        height = 480,
        scale = "zoomEven"
      }
}

main.lua

Now lets work on the main.lua file. We can store the circle in a variable and use that variable later to change other properties of that circle like color for example.

Let’s make a circle called “circle_variable_name” with the center at (160,240) and a radius of 50.

--local nameofcircle = display.newCircle( x-cordinate, y-cordinate, radius )
local circle_variable_name = display.newCircle(160,240,50)

The default color of the circle is white, let’s change the color to red using the setFillColor function. The setFillColor function also needs three parameters which range from 0 to 250 in this order:

• amount of red
• amount of green
• and amount of blue

--nameofcircle:setFillColor(Red,Green,Blue)
circle_variable_name:setFillColor(250, 0, 0)

The full code for the circle is this

local circle_variable_name = display.newCircle(160,240,50)
circle_variable_name:setFillColor(250, 0, 0)

We can also add a stroke, and color to that stroke, to the circle just created with these two functions

--nameofcircle.strokeWidth = any_interger
circle_variable_name.strokeWidth = 3
--nameofcircle:setStrokeColor(Red,Green,Blue)
circle_variable_name:setStrokeColor(0,250,0)

The full code for the circle is

local circle_variable_name = display.newCircle(160,240,50)
circle_variable_name:setFillColor(250, 0, 0)
circle_variable_name.strokeWidth = 3
circle_variable_name:setStrokeColor(0,250,0)

Now to create more than one circle you simply create different variable names like in the following example

local circle = display.newCircle(160,240,50)
circle:setFillColor(100,190,0)

local circle1 = display.newCircle(100,150,30)
circle1:setFillColor(100,90,190)

local circle2 = display.newCircle(160,400,90)
circle2:setFillColor(250,30,190)