keyboardEvent.c

#include <GL/freeglut.h>
#include <GL/gl.h>
#include <stdio.h>
GLfloat r=0.0,g = 0.0,b = 0.0,a =0.0;
void MyKeyboardFunc(unsigned char Key, int x, int y);
void renderFunction()
{
	int i=0;
	glClearColor(r, g, b, a);
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0.0, 0.0, 1.0);
	glPointSize(5) ;
	glFlush();
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowSize(500,500);
	glutInitWindowPosition(100,100);
	glutCreateWindow("OpenGL - First window demo");
 	//Registering a keyboard event callback.
	 //MyKeyboardFunc will now get called on any key board button press.
	glutKeyboardFunc(MyKeyboardFunc);
	glutDisplayFunc(renderFunction);
	glutMainLoop();
	return 0;
}


void MyKeyboardFunc(unsigned char Key, int x, int y)
{
 //Key contains the character we pressed
 //x and y contains the coordinates of the button cursor when the keyboard key was pressed
	switch(Key)
	{
 		case 'r':
		 r = 1.0;g = 0.0;b = 0.0;a = 1.0;
 		glClearColor(r, g, b, a);
 		glClear(GL_COLOR_BUFFER_BIT);
 		glFlush();
 		break;

 		case 'g':
 		r = 0.0;g = 1.0;b = 0.0;a = 1.0;
 		glClearColor(r, g, b, a);
 		glClear(GL_COLOR_BUFFER_BIT);
 		glFlush();
 		break;

 		case 'y':
 		r = 1.0;g = 1.0;b = 0.0;a = 1.0;
		glClearColor(r, g, b, a);
 		glClear(GL_COLOR_BUFFER_BIT);
 		glFlush();
 		break;

 		default: break;
		};
	}