![]() ![]() The following figure illustrates the keyboard input model. Eventually, the thread's message loop removes the message and passes it to the appropriate window procedure for processing. The system removes the message from the system message queue and posts it to the message queue of the appropriate thread. After translating a scan code, the keyboard layout creates a message that includes the scan code, the virtual-key code, and other information about the keystroke, and then places the message in the system message queue. The keyboard device driver interprets a scan code and translates (maps) it to a virtual-key code, a device-independent value defined by the system that identifies the purpose of a key. A keyboard generates two scan codes when the user types a key-one when the user presses the key and another when the user releases the key. The keyboard device driver receives scan codes from the keyboard, which are sent to the keyboard layout where they are translated into messages and posted to the appropriate windows in your application.Īssigned to each key on a keyboard is a unique value called a scan code, a device-dependent identifier for the key on the keyboard. ![]() The system provides language-independent keyboard support by using the language-specific keyboard layout currently selected by the user or the application. The system provides device-independent keyboard support for applications by installing a keyboard device driver appropriate for the current keyboard. An application receives keyboard input in the form of messages posted to its windows. NOTE When using the Virtual Keyboard, only the keyboard_string variable will be updated with the keyboard input.Applications should accept user input from the keyboard as well as from the mouse. There are also some functions that can be used to simulate keypresses:įinally, the following variables are built-in to GameMaker and can be accessed to get information about the keyboard state and input: NOTE These functions will not work when using an on-screen Virtual Keyboard. The following functions are available for use when working with a keyboard: If you need to check for a key character that is not 0 - 9, A - Z or one of the VK constants, then you should be checking one of the keyboard_* variables, like keyboard_lastchar for example: The above code will detect if the "Tab" key is pressed and create an instance of object "obj_Menu" if it is. Instance_create_layer(x, y, "Controllers", obj_Menu) The following is a small example of how to use the vk_ constants: The following constants can only be used with keyboard_check_direct: Virtual Key Constant (vk_*) (keyboard_check_direct only) Constant Keycode representing that any key is pressed Keycode representing that no key is pressed But what if you want to use the arrow keys? Or if you want to modify an action using the "shift" key? Well, for that GameMaker has a series of vk_ constants ( vk_ stands for virtual key) that you can use in place of ord(): Virtual Key Constant (vk_*) Constant The function ord() will return a full UTF8 value, but the keyboard_check*() functions will only detect A - Z and 0 - 9. Note, that using ord() in this way will only function correctly if the input string is only one character in length and is a number from 0 to 9 or a capitalised Roman character from A to Z. So, the above will check the "A" key and if it's being pressed then it'll set the horizontal speed of the object to -5. Typically you'd use a combination of ord() with the keyboard_check*() functions, something like this: ![]() This value can be retrieved for any character using the ord function but, GameMaker also has a series of constants for the most used keyboard special keys and a special functions. You may find some of the built-in variables and constants aren't valid on other platforms and many of the functions won't work on mobiles.Įach input character from a key (or multiple keys) is defined by its UTF8 code, which is a numerical value. NOTE These functions are designed for Windows/Mac/Ubuntu desktop platforms only. There are also some that store all the key presses as a string or that can tell you what the last key pressed was, as well as others that allow you to clear the keyboard state completely. When dealing with the keyboard in GameMaker you have a variety of functions that can be used to recognise different keyboard states like pressed or released. ![]()
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