Bresenham Algorithm

#include <stdlib.h>
#include <stdio.h>

//extern int plot(int x, int y);

int plot(int x, int y, int color)
{
    printf("plot(%d, %d, %d)\n", x, y, color);

}


void swap(int *a, int *b)
{
    int tmp;

    tmp = *a;
    *a = *b;
    *b = tmp;
    printf("swap %d with %d\n", a, b);

}



int line(int x1, int y1, int x2, int y2, int color)
{
    int steep;
    int deltax, deltay;
    int e, x, y, y_step;

    steep = (abs(y2 - y1) > (x2 - x1));

    if (steep) {
        swap(&x1, &y1);
        swap(&x2, &y2);
    }
    if (x1 > x2) {
        swap(&x1, &x2);
        swap(&y1, &y2);
    }
    deltax = x2 - x1;
    deltay = abs(y2 - y1);
    e = x1;
    y = y1;
    if (y1 < y2) {
        y_step = 1;
    } else
        y_step = -1;
    for (x = x1; x <= x2; x++) {
        if (steep)
            plot(y, x, color);
        else
            plot(x, y, color);
        e += deltay;
        if (2 * e >= deltax) {
            y += y_step;
            e -= deltax;
        }
    }
    return 0;
}


int main()
{
    int x1, x2, y1, y2, color;

    x1 = 0;
    y1 = 0;
    x2 = 50;
    y2 = 65;
    color = 1;

    line(x1, y1, x2, y2, color);
}
~
~