// Copyright (c) David Kabala 
// Fall 2009

#include <GL/glut.h>

class SceneManager
{
protected:
    GLenum _DrawPrimitiveType;

public:
    SceneManager(void) : _DrawPrimitiveType(GL_POINTS)
    {
    }

    void init(void)
    {
        glPointSize(5.0f);
        glLineWidth(5.0f);
    }

    void reshape(int w, int h)
    {
        glViewport(0,0,w,h);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(-w/2.0,w/2.0,-h/2.0,h/2.0,-1.0,1.0);
        glMatrixMode(GL_MODELVIEW);
        glutPostRedisplay();
    }

    void display(void)
    {
        glClear(GL_COLOR_BUFFER_BIT);
        glBegin(_DrawPrimitiveType);
            glColor3f(1.0, 1.0, 1.0);  /* white */
            glVertex2i(-100, 100);
            glVertex2i(100, 100);
            glVertex2i(100, -100);
            glVertex2i(-100, -100);
        glEnd();
        glFlush();  /* Single buffered, so needs a flush. */
    }
    
    void keyboard(unsigned char key, int x, int y)
    {
        switch(key)
        {
        case 'z':
            exit(0);
            break;
        case 'p': //Points
            _DrawPrimitiveType = GL_POINTS;
            break;
        case 'l': //Lines
            _DrawPrimitiveType = GL_LINES;
            break;
        case 't': //Triangles
            _DrawPrimitiveType = GL_TRIANGLES;
            break;
        case 'q': //Quads
            _DrawPrimitiveType = GL_QUADS;
            break;
        case 'n': //Polygon
            _DrawPrimitiveType = GL_POLYGON;
            break;
        }
        glutPostRedisplay();
    }
};

SceneManager mgr;

void reshape(int w, int h)
{
    mgr.reshape(w,h);
}

void display(void)
{
    mgr.display();
}
void keyboard(unsigned char key, int x, int y)
{
    mgr.keyboard(key,x,y);
}

int main(int argc, char **argv)
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_SINGLE);
  glutCreateWindow("Primitives");
  glutDisplayFunc(display);
  glutReshapeFunc(reshape);
  glutKeyboardFunc(keyboard);
  mgr.init();
  glutMainLoop();
  return 0;             /* ANSI C requires main to return int. */
}