Praktikum 4 Grafika (Membuat garis DDA dan Bresenham)

/* 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 parameters
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)
{
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);
while(x<xEnd){
x++;
if(p<0)
p+=twoDy;
else{
y++;
p+=twoDyMinusDx;
}
setPixel(x,y);
}
}
void drawMyLine (void)
{
    glClear (GL_COLOR_BUFFER_BIT);
   
    glColor3f(1.0,0.0,0.0);
    glPointSize(4.0);
    GLint x0 = 50;
    GLint y0 = 50;
    GLint xEnd = 150;
    GLint yEnd = 50;
    lineBres(x0,y0,xEnd,yEnd);
   
    glColor3f(0.0,1.0,0.0);
    glPointSize(4.0);
    GLint x1 = 50;
    GLint y1 = 100;
    GLint x2 = 150;
    GLint y2 = 100;
    lineBres(x1,y1,x2,y2);

    glColor3f(0.0,0.0,1.0);
    glPointSize(4.0);
    GLint x3 = 50;
    GLint y3 = 150;
    GLint x4 = 150;
    GLint y4 = 150;
    lineBres(x3,y3,x4,y4);

   
}

int main(int argc, char** argv)
{
//initialize GLUT
glutInit(&argc,argv);
//initialize display mode
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
//set display-window width & height
glutInitWindowSize(400,400);
//set display-window upper-left position
glutInitWindowPosition(0,0);
//create diplay-window with a title
glutCreateWindow("Digital Differential Analyzer Algorithm");
//initialize OpenGL
display();
//call graphics to be displayed on the window
glutDisplayFunc(drawMyLine);
//display everything and wait
glutMainLoop();
return 0;
}