/* October 2002
 * Brian J.Ross
 * Brock University, Dept of Computer Science
 * COSC 3P98 Midterm solution B
 *
 * A simple 2D function plotter.
 */
#if !defined(Linux)
  #include <windows.h>           //Not Linux must be windows
#endif

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <math.h>

#define MINDIM 0
#define MAXDIM 500


struct glob {
   float xmin;
   float xmax;
   float xincr;
};
struct glob global = {-5.0, 5.0, 0.5};


float func(float x) {

	return sin(x);
}

void  initdraw(void) { 

	glClear(GL_COLOR_BUFFER_BIT);

	
	glColor3f(1.0, 0.0, 0.0); // red
	glBegin(GL_LINES);
	   glVertex2f(0.0, -5.0);
	   glVertex2f(0.0, 5.0);
	   glVertex2f(-5.0, 0.0);
	   glVertex2f(5.0, 0.0);
	glEnd();
}

void  plot2d(void) { 
	float x;

	initdraw();
	glColor3f(0.0, 0.0, 0.0);
	glBegin(GL_LINE_STRIP);
	   for (x=global.xmin; x <= global.xmax; x+=global.xincr) {
	       glVertex2f(x, func(x)); 
	   };
	glEnd();
	glFlush();
}

int main(argc, argv)
	int argc;
	char **argv; {

	glutInit(&argc, argv);
	glutInitWindowSize(MAXDIM, MAXDIM);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutCreateWindow("window");

	glutDisplayFunc(plot2d);

	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(global.xmin, global.xmax, global.xmin, global.xmax);
	glClearColor (1.0, 1.0, 1.0, 1.0);

	glutMainLoop();
	return 0;
}