Assignment 2 (Primitive Practice)

gistfile1.cpp

#include <stdlib.h>
#include <GLUT/glut.h>
#include <math.h>


/*************************
::: HELPER VARIABLES ::: *
*************************/

enum MENU_TYPE {
  POINTS,
  LINES,
  LINE_STRIP,
  LINE_LOOP,
  TRIANGLES,
  TRIANGLE_STRIP,
  TRIANGLE_FAN
};

typedef struct Coord_t {
  GLfloat x;
  GLfloat y;
  Coord_t(GLfloat _x, GLfloat _y) : x(_x), y(_y) {}
};

int coords_length = 12;
Coord_t coords[12] = { 
  Coord_t(1.0, 5.0),
  Coord_t(5.0, 1.0),
  Coord_t(2.0, 6.0), 
  Coord_t(6.0, 2.0), 
  Coord_t(3.0, 7.0),
  Coord_t(7.0, 3.0),
  Coord_t(4.0, 8.0),
  Coord_t(8.0, 4.0),
  Coord_t(5.0, 9.0),
  Coord_t(9.0, 5.0),
  Coord_t(6.0, 10.0),
  Coord_t(10.0, 6.0)
};


/************************************
::: HELPER FUNCTIONS DECLARATIONS ::: 
************************************/

void initWindow();
void initMenu();
void menu(int);
void display();
void loopPoints();
void renderPoints();
void renderPointsUsing(int);


/*****************************
::: MAIN PROGRAM EXECUTION ::: 
******************************/

int main(int argc, char** argv) {
  glutInit(&argc, argv);
  initWindow();
  initMenu();
  glutDisplayFunc(display);
  glutMainLoop();
  return 0;
}


/***************************************
::: HELPER FUNCTIONS IMPLEMENTATIONS ::: 
***************************************/

void initWindow() {
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
  glutInitWindowSize(800, 400);
  glutInitWindowPosition(0, 0);
  glutCreateWindow("Primitives");

  glClearColor(1.0, 1.0, 1.0, 0.0);
  glClear(GL_COLOR_BUFFER_BIT);
  gluOrtho2D(0.0, 20.0, 0.0, 12.0);
  glColor3f(1.0, 0.0, 0.0);
}

void initMenu() {
  glutCreateMenu(menu);
  glutAttachMenu(GLUT_RIGHT_BUTTON);
  glutAddMenuEntry("Points",         POINTS);
  glutAddMenuEntry("Lines",          LINES);
  glutAddMenuEntry("Line Strip",     LINE_STRIP);
  glutAddMenuEntry("Line Loop",      LINE_LOOP);
  glutAddMenuEntry("Triangles",      TRIANGLES);
  glutAddMenuEntry("Triangle Strip", TRIANGLE_STRIP);
  glutAddMenuEntry("Triangle Fan",   TRIANGLE_FAN);
}

void menu(int item) {
  glClear(GL_COLOR_BUFFER_BIT);
  renderPoints();

  switch (item) {
    case POINTS:
      renderPointsUsing(GL_POINTS);
    break;
    case LINES:
      renderPointsUsing(GL_LINES);
    break;
    case LINE_STRIP:
      renderPointsUsing(GL_LINE_STRIP);
    break;
    case LINE_LOOP:
      renderPointsUsing(GL_LINE_LOOP);
    break;
    case TRIANGLES:
      renderPointsUsing(GL_TRIANGLES);
    break;
    case TRIANGLE_STRIP:
      renderPointsUsing(GL_TRIANGLE_STRIP);
    break;
    case TRIANGLE_FAN:
      renderPointsUsing(GL_TRIANGLE_FAN);
    break;
    default:
    break;
  }
  glFlush();
}

void display() {
  glPointSize(5);
  glLineWidth(5);
  renderPoints();
  glFlush();
}

void renderPoints() {
  glBegin(GL_POINTS);
    for(int i = 0; i < coords_length; ++i) {
      glVertex2f(coords[i].x, coords[i].y);
    }
  glEnd();
}

void renderPointsUsing(int primitive) {
  glBegin(primitive);
  for(int i = 0; i < coords_length; ++i) {
    glVertex2f(coords[i].x + 10.0, coords[i].y);
  }
  glEnd();
}