Lab_12/15var (IV semester) CG

#include "stdafx.h"
#include <stdio.h>
#include <math.h>
#include "glut.h"
#include <iostream>
#include <string>
using namespace std;
int width = 960, height = 720;

void PutPixel(int x, int y) {
    glBegin(GL_POINTS);
    glColor3f(1.0, 0.0, 0.0);
    glVertex2i(x, y);
    glEnd();
}

void DrawCircle(int x, int y, int r) {
    int x1, y1, yk = 0;
    int sigma, delta, f;
    x1 = 0;
    y1 = r;
    delta = 2 * (1 - r);
    do {
        PutPixel(x + x1, y + y1);
        PutPixel(x - x1, y + y1);
        PutPixel(x + x1, y - y1);
        PutPixel(x - x1, y - y1);
        f = 0;
        if (y1 < yk)
            break;

        if (delta < 0) {
            sigma = 2 * (delta + y1) - 1;
            if (sigma <= 0) {
                x1++;
                delta += 2 * x1 + 1;
                f = 1;
            }
        }
        else if (delta > 0) {
            sigma = 2 * (delta - x1) - 1;
            if (sigma > 0){
                y1--;
                delta += 1 - 2 * y1;
                f = 1;
            }
        }
        if (!f) {
            x1++;
            y1--;
            delta += 2 * (x1 - y1 - 1);
        }
    } while (1);
}

void DrawLine(int x1, int y1, int x2, int y2) {
    int dx, dy, i, e;
    int incx, incy, inc1, inc2;
    int x, y;
    dx = x2 - x1;
    dy = y2 - y1;
    if (dx < 0) dx = -dx;
    if (dy < 0) dy = -dy;
    incx = 1;
    if (x2 < x1) incx = -1;
    incy = 1;
    if (y2 < y1) incy = -1;
    x = x1; y = y1;
    if (dx > dy) {
        PutPixel(x, y);
        e = 2 * dy - dx;
        inc1 = 2 * (dy - dx);
        inc2 = 2 * dy;
        for (i = 0; i<dx; i++) {
            if (e >= 0) {
                y += incy;
                e += inc1;
            }
            else
                e += inc2;
            x += incx;
            PutPixel(x, y);
        }

    }
    else {
        PutPixel(x, y);
        e = 2 * dx - dy;
        inc1 = 2 * (dx - dy);
        inc2 = 2 * dx;
        for (i = 0; i<dy; i++) {
            if (e >= 0) {
                x += incx;
                e += inc1;
            }
            else
                e += inc2;
            y += incy;
            PutPixel(x, y);
        }
    }

}
void Display(void) {
    glClear(GL_COLOR_BUFFER_BIT);
    DrawCircle(320, 240, 200);
    DrawLine(320, 440, 320, 40);
    DrawLine(120, 240, 520, 240);

    DrawLine(120, 240, 420, 413);
    DrawLine(120, 240, 420, 67);
    DrawLine(420, 413, 420, 67);

    glFlush();
}
void Init() {
    glClearColor(1.0, 1.0, 1.0, 0);
    glColor3f(0.0, 0.0, 0.0);
    gluOrtho2D(0, width, 0, height);
}

void main(int argc, char **argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowPosition(0, 0);
    glutInitWindowSize(width, height);
    glutCreateWindow("Bresenham");
    Init();
    glutDisplayFunc(Display);
    glutMainLoop();
}