5.B] Explain OpenGL interactive input device functions:
i) GLUT Keyboard Functions
ii) GLUT Mouse Functions
Answer:
In OpenGL, interactive input device functions are used to handle user inputs from keyboards and mice. These functions are part of the GLUT (OpenGL Utility Toolkit) library, which simplifies the creation of OpenGL applications and handling of user inputs.
Here’s an explanation of the GLUT keyboard and mouse functions:
i) GLUT Keyboard Functions
GLUT provides several functions to handle keyboard input. These functions allow you to respond to key presses and releases, enabling interactive controls within an OpenGL application.
glutKeyboardFunc(void (*func)(unsigned char key, int x, int y))
- Description: Registers a callback function to handle standard ASCII keyboard input.
- Parameters:
func: A pointer to the callback function that will be called when a key is pressed.key: The ASCII value of the key pressed.x,y: The current mouse coordinates when the key is pressed.
- Usage: Used to capture input from standard keys (e.g., ‘a’, ‘b’, ‘1’).
ii) GLUT Mouse Functions
GLUT also provides several functions to handle mouse input, allowing users to interact with OpenGL applications using mouse clicks and movements.
glutMouseFunc(void (*func)(int button, int state, int x, int y))
- Description: Registers a callback function to handle mouse button events.
- Parameters:
func: A pointer to the callback function that will be called on mouse button presses and releases.button: The mouse button pressed or released (e.g., GLUT_LEFT_BUTTON, GLUT_RIGHT_BUTTON).state: The state of the button (e.g., GLUT_DOWN, GLUT_UP).x,y: The mouse coordinates when the button event occurs.
- Usage: Used to detect and respond to mouse button clicks and releases.