exp4bresstairs.txt

#include<stdio.h>
#include<math.h>
#include<GL/freeglut.h>
#include<GL/gl.h>

//GLOBAL VARIABLES
int xf1, yf1, xf2, yf2;
bool selected = false;
int l;

//FUNCTION DEFINITIONS

//plot functin to plot a pixel
void plot(int x, int y){
    glBegin(GL_POINTS);
    glVertex2i(x,y);
    glEnd();
    glFlush();
}//end of plot function

//bresenham line drawing algorihm
void bresenham(int x1, int y1, int x2, int y2){
    int x = x1;
    int y = y1;
    int i;
    
    int dx = x2 - x1;
    int dy = y2 - y1;
    
    int p = 2*dy - dx;
    
    int x_inc = x2>=x1 ? 1 : -1;
    int y_inc = y2>=y1 ? 1 : -1;
    
    if(dx >= dy){
        plot(x,y);
        for(i=0;i<dx;i++){
        
        if(p>0){
            y = y + y_inc;
            p = p - 2*dx;        
        }
        
        x = x + x_inc;
        p = p + 2*dy;
        plot(x,y); 
        }     
    }//end of if
    
    else{
        plot(x,y);
        for(i=0;i<dy;i++){
        if(p>0){
            x = x + x_inc;
            p = p - 2*dy;        
        }
        
        y = y + y_inc;
        p = p + 2*dx; 
        plot(x,y); 
        
        }  
    }
    
    glFlush();

}//end of bresenham function

//draw staircase pattern
void draw_pattern(){

    int h = l/6;
    int b = l/6;
    
    glColor3f(1.0,1.0,1.0);
    bresenham(xf1, yf1, xf1+l, yf1);
    bresenham(xf1+l,yf1, xf1+l, yf1+l); 
    
    int x,y;
    int i;
    
    x = xf1;
    y = yf1;
    
    
    for(i=0;i<6;i++){
    bresenham(x, y, x, y+h);
    bresenham(x, y+h, x+b, y+h);
        x = x + b;
        y = y + h;
    }
    

}//end of draw pattern functio

//intialize function to initialize buffer
void init(){
    glClearColor(1.0,0.0,0.0,1.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0,640,0,480);
    glFlush();
}//end of init function

//display function
void display(){
    glClear(GL_COLOR_BUFFER_BIT);
    glFlush();

}//end of display function


//mouse click function
void mouse(int button, int state, int x, int y){
    if(button == GLUT_LEFT_BUTTON){
        if(state == GLUT_DOWN){
            if(selected == false){
                xf1 = x;
                yf1 = 480 - y;
                glColor3f(0.0,0.0,0.0);
                glPointSize(5);
                plot(xf1,yf1);
                glPointSize(2);
                draw_pattern();
               
            }//end of if select
                     
        }//end of if state
    }//end of if button
    
    glFlush();
}//end of mouse function


 
//main function
int main(int argc, char **argv){
    printf("\nEnter lenght :: ");
    scanf("%d", &l);
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //intitializng diplay mode
    glutInitWindowSize(640,480);//initializing window size
    glutInitWindowPosition(100,100);//initializing window position 
    glutCreateWindow("Staircase");
    init();
    glutDisplayFunc(display);
    glutMouseFunc(mouse);
    glutMainLoop();
    return 0;

}//end of main function