Grafika komputer prak 4 membuat objek garis segitiga

/* Praktikum 04
* Membuat objek garis dengan DDA dan Bresenham
*/
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <glut.h>
#include <math.h>
void display(void)
{
//set display-window background color to white
glClearColor(1.0,1.0,1.0,0.0);
//set projection paramaters
glMatrixMode(GL_PROJECTION);
gluOrtho2D(0.0,300.0,0.0,300.0);
}
void setPixel(GLint xCoordinate, GLint yCoordinate)
{
glBegin(GL_POINTS);
glVertex2i(xCoordinate,yCoordinate);
glEnd();
glFlush();
}
//Procedure Bresenham line-drawing untuk |m| < 1.0
void lineBres(GLint x0, GLint y0, GLint xEnd, GLint yEnd)
{ //kordinat
GLint dx = (float)fabs((float) xEnd - x0);
GLint dy = (float)fabs((float) yEnd - y0);
GLint p = 2 * dy - dx;
GLint twoDy = 2 * dy;
GLint twoDyMinusDx = 2 * (dy-dx);
GLint x,y;
// determine which endpoint to use as start position
if(x0 > xEnd){
x = xEnd;
y = yEnd;
xEnd = x;
}else{
x = x0;
y = y0;
}
setPixel(x,y);