#include "stdafx.h"
#include<windows.h>
#include<GL/gl.h>
#include<GL/glu.h>
#include<GL/glaux.h>
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#define INF 0x3f3f3f3f

void init(){
	glClearColor(0.0,0.0,0.0,1.0);
}
void Set(int x,int y,int c1,int c2,int c3){
	glVertex2f(x,y);
}

void solve(int x0,int y0,int x1,int y1,int d1,int d2,int d,int c1,int c2,int c3){
	
	int x=x0,y=y0;
	if(x0>x1){
		x=x1,x1=x0;
		y=y1,y1=y0;
	}
    glColor3f(c1,c2,c3);
	glBegin(GL_POINTS);
		Set(x,y,c1,c2,c3);
		while(x<x1){
			if(d<=0){
				y++;
				d+=d1;
			} else {
				d+=d2;
			}
			Set(x,y,c1,c2,c3);
			x++;
		}
	glEnd();
}
void MidpointLine(int x0,int y0,int x1,int y1,int c1,int c2,int c3){
	double k=0.0;
	int d1,d2,a,b,d;
	if(x0==x1)k=INF;
	else {
		k=1.0*(y0-y1)/(x0-x1);
	}
	if(k>1.0){
		a=y0-y1,b=x1-x0,d=b+a+b;
		d1=b+b,d2=2*(a+b);
		solve(x0,y0,x1,y1,d1,d2,d,c1,c2,c3);
	}
	else {
		a=y0-y1,b=x1-x0,d=a+a+b;
		d2=a+a,d1=2*(a+b);
		solve(x0,y0,x1,y1,d1,d2,d,c1,c2,c3);
	}
}
void DDA(int x0,int y0,int x1,int y1,int c1,int c2,int c3){
	int x=x0,y=y0;
	double yi=0;
	
	if(x0>x1){
		x=x1,x1=x0;
		y=y1,y1=y0;
	}
	double m=1.0*(y0-y1)/(x0-x1);
	double b=y0-m*x0;
	glColor3f(c1,c2,c3);
	glBegin(GL_POINTS);
		Set(x,y,c1,c2,c3);
		while(x<x1){
			yi=m*x+b;
			Set(x,yi,c1,c2,c3);
			x++;
		}
	glEnd();
}
void CALLBACK draw(){
	
	glClear(GL_COLOR_BUFFER_BIT);
	int x0,y0,x1,y1;
	x0=y0=30;
	x1=130,y1=100;
	MidpointLine(x0,y0,x1,y1,0,1,0);
	DDA(x0,y0+10,x1,y1+10,0,1,0);
	glColor3f(1,0,0);
	glBegin(GL_LINES);
		glVertex2f(x0,y0+20);
		glVertex2f(x1,y1+20);
	glEnd();
	glFlush();
}

int main(int argc, char* argv[]){
	auxInitDisplayMode(AUX_SINGLE|AUX_RGBA);
	auxInitPosition(100,100,500,500);
	auxInitWindow("CGOpenGL");
	init();
	auxMainLoop(draw);
	return 0;
}