ComputerGraphicsLab/prog5.cpp at main · Aneesh-M-Bhat/ComputerGraphicsLab · GitHub

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#include <stdio.h>
#include <GL/glut.h>

double xmin = 50, ymin = 50, xmax = 100, ymax = 100;
double xvmin = 200, yvmin = 200, xvmax = 300, yvmax = 300;

const int LEFT = 1;
const int RIGHT = 2;
const int BOTTOM = 4;
const int TOP = 8;

int computeOutCode(double x, double y)
{
    int code = 0;
    if (y > ymax)
        code |= TOP;
    else if (y < ymin)
        code |= BOTTOM;
    if (x > xmax)
        code |= RIGHT;
    else if (x < xmin)
        code |= LEFT;
    return code;
}

void drawRectangle(double xmin, double xmax, double ymin, double ymax)
{
    glBegin(GL_LINE_LOOP);
    glVertex2f(xmin, ymin);
    glVertex2f(xmax, ymin);
    glVertex2f(xmax, ymax);
    glVertex2f(xmin, ymax);
    glEnd();
}

void drawLine(double x0, double x1, double y0, double y1)
{
    glBegin(GL_LINES);
    glVertex2d(x0, y0);
    glVertex2d(x1, y1);
    glEnd();
}

void cohenSutherland(double x0, double y0, double x1, double y1)
{
    int outcode0, outcode1, outcodeOut;
    bool accept = false, done = false;
    outcode0 = computeOutCode(x0, y0);
    outcode1 = computeOutCode(x1, y1);
    do
    {
        if (!(outcode0 | outcode1)) // Inside
        {
            accept = true;
            done = true;
        }
        else if (outcode0 & outcode1) // Outside (diff regions)
            done = true;
        else
        {
            double x, y;
            double m = (y1 - y0) / (x1 - x0);
            outcodeOut = outcode0 ? outcode0 : outcode1;
            if (outcodeOut & TOP)
            {
                x = x0 + (1 / m) * (ymax - y0);
                y = ymax;
            }
            else if (outcodeOut & BOTTOM)
            {
                x = x0 + (1 / m) * (ymin - y0);
                y = ymin;
            }
            else if (outcodeOut & RIGHT)
            {
                y = y0 + m * (xmax - x0);
                x = xmax;
            }
            else
            {
                y = y0 + m * (xmin - x0);
                x = xmin;
            }
            /* Intersection calculations over */
            if (outcodeOut == outcode0)
            {
                x0 = x;
                y0 = y;
                outcode0 = computeOutCode(x0, y0);
            }
            else
            {
                x1 = x;
                y1 = y;
                outcode1 = computeOutCode(x1, y1);
            }
        }
    } while (!done);
    if (accept)
    {
        double sx = (xvmax - xvmin) / (xmax - xmin);
        double sy = (yvmax - yvmin) / (ymax - ymin);
        double vx0 = xvmin + (x0 - xmin) * sx;
        double vy0 = yvmin + (y0 - ymin) * sy;
        double vx1 = xvmin + (x1 - xmin) * sx;
        double vy1 = yvmin + (y1 - ymin) * sy;
        drawRectangle(xvmin, xvmax, yvmin, yvmax);
        drawLine(vx0, vx1, vy0, vy1);
    }
}

void display()
{
    double x0 = 60, y0 = 20, x1 = 80, y1 = 120;
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1, 1, 1);
    drawLine(x0, x1, y0, y1);
    drawRectangle(xmin, xmax, ymin, ymax);
    cohenSutherland(x0, y0, x1, y1);
    glFlush();
}

void init()
{
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutCreateWindow("Cohen Sutherland Line Clipping Algorithm");
    glClearColor(0, 0, 0, 1);
    gluOrtho2D(0, 500, 0, 500);
    glutDisplayFunc(display);
    glutMainLoop();
}

int main(int argc, char **argv)
{
    glutInit(&argc, argv);
    init();
}