/*
 Compiling C++/OpenGL programs in OS X

 1. Open up a text file called "gcomp" and cut and paste the following code into it.

     g++ -o $1 $1.cpp -L/Developer/SDKs/MacOSX10.5.sdk/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries -L/usr/local/lib  -lGL  -lGLU -framework GLUT

 2. At the terminal prompt type: chmod u+x gcomp
    This makes the file gcomp into an executable.

 3. If your program is called myProg.cpp, just type "gcomp myProg".
    and run the program by typing "myProg".


*/

#include </Developer/SDKs/MacOSX10.5.sdk/System/Library/Frameworks/OpenGL.framework/Headers/gl.h>
#include </Developer/SDKs/MacOSX10.5.sdk/System/Library/Frameworks/OpenGL.framework/Headers/glu.h>
#include </Developer/SDKs/MacOSX10.5.sdk/System/Library/Frameworks/GLUT.framework/Headers/glut.h>
#include <iostream>
#include <fstream>

using namespace std;


void initWindow(int xres, int yres)
{
}

void setPixel(int x, int y, float color[])
{
  glRasterPos2i(x,y);
  glDrawPixels(1,1,GL_RGB,GL_FLOAT,color);
}



void line(int x1, int y1,int x2,int y2,float color[])

{
   // Implement Bresenham's algorithm here
   // modified so that it works for all slopes
   // and both positive and negative dx and dy.
   // When a pixel (x,y) is found on the line
   // call setPixel(x,y,color)

   // Test code that you will remove:
   for (int i=x1;i<x2;i++) 
      setPixel(i,y1,color);
}

void makeList(char *argv)
{
     ifstream fin;
     int x1,y1,x2,y2;

     fin.open(argv);

     float color[3] = {0.0,0.0,0.0};

     glDeleteLists(1,1);
     glNewList(1,GL_COMPILE);
         while ( (fin>>x1) != 0) 
            {
              fin >> y1 >> x2 >> y2;
              line(x1,y1,x2,y2,color);  
              glFlush();
            }
     glEndList();

}


void initGraphics(int xres,int yres,char *argv)

{
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();

     // This puts origin at center of the window

     gluOrtho2D((double) -xres/2,(double) xres/2,(double) -yres/2,(double) yres/2);
     glTranslatef(0.375, 0.375, 0.0);
     glMatrixMode(GL_MODELVIEW);
     makeList(argv);
     
}
void display(void)
{
        glClearColor(1.0,1.0,1.0,0.0);
        glClear(GL_COLOR_BUFFER_BIT);  // Clear window
        glCallList(1);
        glutSwapBuffers();
        glCallList(1);
}


void button_event(int button, int state, int x, int y)
{
}

void key_event(unsigned char key, int x, int y)
{
    switch (key) {
       case 'q' : exit(0);
     }
    glutPostRedisplay();

}

void mouse_motion(int x, int y)
{
}

int main(int argc, char *argv[])

{


   // Initialize glut parameters

	glutInit(&argc, argv); /* initialize glut */
        glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE);

   // enter xres, yres, xpos, ypos of window and
   // open a window 
       
        int xres= 801, yres = 801, xpos = 0, ypos = 0;
       
        glutInitWindowSize(xres,yres);
        glutInitWindowPosition(xpos,ypos);
        glutCreateWindow(argv[0]);


   // Your function to set initial graphics to be displayed in the window

        initGraphics(xres,yres,argv[1]);  // argv[1] is the name of the input file

   // Your function Display is called whenever glutPostRedisplay() is invoked;

        glutDisplayFunc(display);

   // Your function that is called when interrupt is generated

        glutMouseFunc(button_event);
        glutKeyboardFunc(key_event);
        glutMotionFunc(mouse_motion);
  
   // Call your Display function and turn over control to window manager

        display();
        glutMainLoop();
}