#include<Gl/glut.h>

void LineDDA(int x0, int y0, int x1, int y1 /* int color*/){
    int x, dy, dx, y;
    float m;
    dx = x1 - x0;
    dy = y1 - y0;
    m = dy / dx;
    y = y0;

    glColor3f(1.0f, 1.0f, 0.0f);
    glPointSize(1);
    for(x = x0; x <= x1; x++){
        glBegin(GL_POINTS);
        glVertex2i(x, (int)(y + 0.5));
        glEnd();
        y += m;
    }
}

void myDisplay(void){
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0f, 0.0f, 0.0f);
    glRectf(25.0, 25.0, 75.0, 75.0);

    glPointSize(5);
    glBegin(GL_POINT);
    glColor3f(0.0f, 1.0f, 0.0f); glVertex2f(0.0f, 0.0f);
    glEnd();

    LineDDA(0, 0, 200, 300);

    glBegin(GL_LINES);
    glColor3f(1.0f, 0.0f, 0.0f); glVertex2f(100.0f, 0.0f);
    glColor3f(0.0f, 1.0f, 0.0f); glVertex2f(180.0f, 240.0f);
    glEnd();

    glFlush();
}
void Init(){
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glShadeModel(GL_FLAT);
}
void Reshape(int w, int h){
    glViewport(0, 0, (GLsizei)w, (GLsizei) h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0.0, (GLdouble)w, 0.0, (GLdouble)h);
}

int main(int argc, char *argv[]){
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
    glutInitWindowPosition(100, 100);
    glutInitWindowSize(400, 400);
    glutCreateWindow("Hello World!");
    Init();
    glutDisplayFunc(myDisplay);
    glutReshapeFunc(Reshape);
    glutMainLoop();
    return 0;
}