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01. Background color	Tutorials	03. Spheres

02. Mouse

In this tutorial we are going to set background color on mouse button press.

Estimated completion time: 5 minutes.

Table of contents

• Mouse buttons
• Toggle background color
• Summary

Mouse buttons

Let's detect mouse buttons' presses and releases:

local mouse = main.application.mouse
mouse.pressedButtonsChanged:addCallback(
    function()
        print("Mouse buttons have been pressed or released")
        print("Pressed buttons:", #mouse.pressedButtons)
    end
)

Run in ogse

Let's see into API we introduced:

• main.application.mouse instance lets you get current mouse (finger) properties like position, pressed mouse buttons and subscribe to changes of the properties
• main.application.mouse.pressedButtons is an array of pressed mouse buttons
• main.application.mouse.pressedButtonsChanged is a notification instance (core.Reporter) that reports notifications when mouse buttons are pressed or released
  • to subscribe to all notifications, we use core.Reporter's addCallback() method:

    main.application.mouse.pressedButtonsChanged:addCallback(
        function()
            print("Mouse buttons have been pressed or released")
        end
    )

• core namespace hosts functionality used throughout whole application
• core.Reporter class implements Publish-subscribe pattern to simplify event circulation among independent application parts
• core.Reporter:addCallback() method allows one to subscribe to all notifications of a specific core.Reporter instance

Notes:

• pressedButtonsChanged is a notification instance we subscribe to
• addCallback() is a method of pressedButtonsChanged instance
• pressedButtonsChanged and addCallback are separated by : because it's a method call
• function() ... end block represents a callback function (closure) to be executed each time notification is reported
• # operator returns number of items of an array

Have a look at the debug console. You should see output similar to this when you press mouse button(s):

Mouse buttons have been pressed or released
Pressed buttons:    1
Mouse buttons have been pressed or released
Pressed buttons:    0
Mouse buttons have been pressed or released
Pressed buttons:    1
Mouse buttons have been pressed or released
Pressed buttons:    2
Mouse buttons have been pressed or released
Pressed buttons:    1
Mouse buttons have been pressed or released
Pressed buttons:    0

Toggle background color

Let's set background color to red when at least one mouse button is pressed, and revert background color back to default 0.2, 0.2, 0.4 when none of mouse buttons is pressed:

local DEFAULT_COLOR = {0.2, 0.2, 0.4}
local PRESSED_COLOR = {1.0, 0.0, 0.0}

local mouse = main.application.mouse
local camera = main.application.camera

mouse.pressedButtonsChanged:addCallback(
    function()
        if (#mouse.pressedButtons > 0)
        then
            camera.clearColor = PRESSED_COLOR
        else
            camera.clearColor = DEFAULT_COLOR
        end
    end
)

Run in ogse

Now background color is red when you hold mouse button(s).

Summary

You have successfully detected mouse buttons' presses/releases and toggled background color.

< Back	Index	Next >
01. Background color	Tutorials	03. Spheres