GLUT Tutorial – How to detect a Mouse Click and Mouse Motion

In previous tutorial, we discussed about handling Keyboard event using GLUT. In this tutorial we pay our close attention towards Detecting Mouse click and Mouse motion.

Detecting Mouse Click
GLUT provides a function glutMouseFunc which is responsible for detecting mouse click generated by a program. Its syntax is
void glutMouseFunc(void (*func)(int button, int state, int x, int y));
Where,

func –> Function that handles the mouse event i.e. when mouse click is detected, func is called

func must have three parameters, as we see in above syntax The first parameter is button, its value is one of the following

GLUT_LEFT_BUTTON – when left mouse button click is detected GLUT_RIGHT_BUTTON  – when right mouse button click is detected GLUT_MIDDLE_BUTTON – when middle mouse button click is detected

The second parameter is state, its value is one of the following

GLUT_DOWN – When mouse button is pressed GLUT_UP – When mouse button is released

When callback is generated with GLUT_DOWN GLUT environment assumes that GLUT_UP comes afterward even if mouse is not inside the window.

Other two parameters x and y are coordinates of the point where mouse pointer is moved.

Detecting Mouse Motion
GLUT provides two types of function as according to types of motion detection either Active Motion or Passive Motion. Active Motion refers to the Motion of mouse when there is Click and Passive motion refers to motion of a mouse without a click. The syntax of two functions are

glutMotionFunc(void (*func)(int x, int y)); //for Active motion

glutMousePassiveMotionFunc(void (*func)(int x, int y)) // for Passive motion

Where,

func –> Function that responsible for handling respective motion

x, y –> coordinates of the mouse relative to upper left corner of window