OpenGL Screencast 11 part 2: Code Organization

initialization.c

#include "screencasts.h"

void initializeGlobals()
{
  windowName = "OpenGL screenscasts 11: Code Organization";
  windowWidth = 500;
  windowHeight = 450;

  toggleAxes = 0;
  toggleValues = 1;
  toggleMode = 0;

  dim = 5.0;
  th = 340;
  ph = 30;
  fov = 55;
  asp = 1;
}

initialization.h

void initializeGlobals(void);

interaction.c

#include "screencasts.h"

/*
 *  windowKey()
 *  ------
 *  GLUT calls this routine when a non-special key is pressed
 */
void windowKey(unsigned char key,int x,int y)
{
  /*  Exit on ESC */
  if (key == 27) exit(0);
  else if (key == 'a' || key == 'A') toggleAxes = 1-toggleAxes;
  else if (key == 'v' || key == 'V') toggleValues = 1-toggleValues;
  else if (key == 'm' || key == 'M') toggleMode = 1-toggleMode;
  /*  Change field of view angle */
  else if (key == '-' && key>1) fov--;
  else if (key == '+' && key<179) fov++;
  /*  Change dimensions */
  else if (key == 'D') dim += 0.1;
  else if (key == 'd' && dim>1) dim -= 0.1;

  displayProject();
  glutPostRedisplay();
}

/*
 *  windowMenu
 *  ------
 *  Window menu is the same as the keyboard clicks
 */
void windowMenu(int value)
{
  windowKey((unsigned char)value, 0, 0);
}

/*
 *  windowSpecial()
 *  ------
 *  GLUT calls this routine when an arrow key is pressed
 */
void windowSpecial(int key,int x,int y)
{
  /*  Right arrow key - increase azimuth by 5 degrees */
  if (key == GLUT_KEY_RIGHT) th += 5;
  /*  Left arrow key - decrease azimuth by 5 degrees */
  else if (key == GLUT_KEY_LEFT) th -= 5;
  /*  Up arrow key - increase elevation by 5 degrees */
  else if (key == GLUT_KEY_UP) ph += 5;
  /*  Down arrow key - decrease elevation by 5 degrees */
  else if (key == GLUT_KEY_DOWN) ph -= 5;

  /*  Keep angles to +/-360 degrees */
  th %= 360;
  ph %= 360;

  displayProject();
  glutPostRedisplay();
}

interaction.h

void windowKey(unsigned char key,int x,int y);
void windowMenu(int value);
void windowSpecial(int key,int x,int y);

models.c

#include "screencasts.h"

/*
 *  spike
 *  ------
 *  Draw a spike
 *     at (x, y, z)
 *     radius r, height h, with 360/deg sides
 *     rotated ox around the x axis
 *     rotated oy around the y axis
 *     rotated oz around the z axis
 */
void spike(double x, double y, double z,
	   double r,double h,int deg,
	   double ox,double oy,double oz)
{
  glPushMatrix();
  glRotated(oz,0,0,1);
  glRotated(oy,0,1,0);
  glRotated(ox,1,0,0);

  cone(x,y,z, r,h,deg);
  glPopMatrix();
}

/*
 *  towers
 *  ------
 *  Draw a tower
 *     at (x,y,z)
 *     dimensions (dx,dy,dz)
 *     rotated th about the y axis
 */
void tower(double x,double y,double z,
	   double dx,double dy,double dz,
	   double th)
{
  glPushMatrix();
  /*  Transformation  */
  glTranslated(x,y,z);
  glRotated(th,0,1,0);
  glScaled(dx,dy,dz);

  cube(0,1.5,0, 1,3,1, 0);
  cube(0,3.5,0, 2,1,2, 45);
  spike(0,1,-3.5, 0.5,1, 90, 90,0,0);
  spike(0,1,3.5, 0.5,1, 90, -90,0,0);
  spike(-3.5,1,0, 0.5,1, 90, 0,0,-90);
  spike(3.5,1,0, 0.5,1, 90, 0,0,90);

  glPopMatrix();
}

models.h

void spike(double x, double y, double z,
	   double r,double h,int deg,
	   double ox,double oy,double oz);
void tower(double x,double y,double z,
	   double dx,double dy,double dz,
	   double th);

print.c

#include "screencasts.h"

#define LEN 8192
void printv(va_list args, const char* format)
{
  char buf[LEN];
  char* ch=buf;
  vsnprintf(buf,LEN,format,args);
  while (*ch)
    glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18,*ch++);
}

void print(const char* format, ...)
{
  va_list args;
  va_start(args,format);
  printv(args,format);
  va_end(args);
}

void printAt(int x, int y, const char* format, ...)
{
  va_list args;
  glWindowPos2i(x,y);
  va_start(args,format);
  printv(args,format);
  va_end(args);
}

print.h

void printv(va_list args, const char* format);
void print(const char* format, ...);
void printAt(int x, int y, const char* format, ...);

screencasts.h

#ifndef SCREENCASTS
#define SCREENCASTS

/* standard headers */
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <math.h>
#include <time.h>

/* OpenGL and friends */
#ifdef USEGLEW
#include <GL/glew.h>
#endif
#define GL_GLEXT_PROTOTYPES
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

/* includes */
#include "common.h" /* common is just defines */
#include "print.h"  /* printing functions */
#include "error.h"  /* error convenience */
#include "shapes.h" /* basic shapes (cube, cone, etc) */
#include "models.h" /* complex objects */
#include "interaction.h"    /* user interactions (keyboard, mouse, etc) */
#include "initialization.h" /* initialization */
#include "draw.h"    /* draw -> draw whatever objects in the scene */
#include "display.h" /* display -> setup scene to draw */

/* GLOBALS (externs required here) */
/* Don't forget to initialize globals! */
/* window info */
extern char *windowName;
extern int windowWidth;
extern int windowHeight;

/* toggle views */
extern int toggleAxes;   /* toggle axes on and off */
extern int toggleValues; /* toggle values on and off */
extern int toggleMode;   /* projection mode */

/* view */
extern double dim;/* dimension of orthogonal box */
extern int th;    /* azimuth of view angle */
extern int ph;    /* elevation of view angle */
extern int fov;   /* field of view for perspective */
extern int asp;   /* aspect ratio */

#endif

shapes.c

#include "screencasts.h"

/*
 *  cube
 *  ------
 *  Draw a cube
 *     at (x,y,z)
 *     dimensions (dx,dy,dz)
 *     rotated th about the y axis
 */
void cube(double x,double y,double z,
	  double dx,double dy,double dz,
	  double th)
{
  /*  Cube vertices */
  GLfloat vertA[3] = { 0.5, 0.5, 0.5};
  GLfloat vertB[3] = {-0.5, 0.5, 0.5};
  GLfloat vertC[3] = {-0.5,-0.5, 0.5};
  GLfloat vertD[3] = { 0.5,-0.5, 0.5};
  GLfloat vertE[3] = { 0.5, 0.5,-0.5};
  GLfloat vertF[3] = {-0.5, 0.5,-0.5};
  GLfloat vertG[3] = {-0.5,-0.5,-0.5};
  GLfloat vertH[3] = { 0.5,-0.5,-0.5};

  glPushMatrix();
  /*  Transform cube */
  glTranslated(x,y,z);
  glRotated(th,0,1,0);
  glScaled(dx,dy,dz);

  /* Cube */
  glBegin(GL_QUADS);
  /* front => ABCD yellow */
  glColor3f(1.0,1.0,0.0);
  glVertex3fv(vertA);
  glVertex3fv(vertB);
  glVertex3fv(vertC);
  glVertex3fv(vertD);
  /* back => FEHG red */
  glColor3f(1.0,0.0,0.0);
  glVertex3fv(vertF);
  glVertex3fv(vertE);
  glVertex3fv(vertH);
  glVertex3fv(vertG);
  /* right => EADH green */
  glColor3f(0.0,1.0,0.0);
  glVertex3fv(vertE);
  glVertex3fv(vertA);
  glVertex3fv(vertD);
  glVertex3fv(vertH);
  /* left => BFGC blue */
  glColor3f(0.0,0.0,1.0);
  glVertex3fv(vertB);
  glVertex3fv(vertF);
  glVertex3fv(vertG);
  glVertex3fv(vertC);
  /* top => EFBA turquoise */
  glColor3f(0.0,1.0,1.0);
  glVertex3fv(vertE);
  glVertex3fv(vertF);
  glVertex3fv(vertB);
  glVertex3fv(vertA);
  /* bottom => DCGH pink */
  glColor3f(1.0,0.0,1.0);
  glVertex3fv(vertD);
  glVertex3fv(vertC);
  glVertex3fv(vertG);
  glVertex3fv(vertH);
  glEnd();

  glPopMatrix();
}

/*
 *  cone
 *  ------
 *  Draws a cone
 *     at (x,y,z)
 *     with radius r and height h
 *     with 360/deg sides
 */
void cone(double x,double y,double z,
	  double r,double h,int deg)
{
  int k;
  glPushMatrix();

  /*  Transformation */
  glTranslated(x,y,z);
  glScaled(r,h,r);
  glRotated(-90,1,0,0);

  /* sides */
  glBegin(GL_TRIANGLES);
  for (k=0;k<=360;k+=deg){
    glColor3f(0.0,0.0,1.0);
    glVertex3f(0,0,1);
    glColor3f(0.0,1.0,1.0);
    glVertex3f(Cos(k),Sin(k),0);
    glColor3f(1.0,0.0,1.0);
    glVertex3f(Cos(k+deg),Sin(k+deg),0);
  }
  glEnd();

  /* bottom circle */ 
  /* rotate back */
  glRotated(90,1,0,0);
  glBegin(GL_TRIANGLES);
  glColor3f(1.0,1.0,0.0);
  for (k=0;k<=360;k+=deg) {
    glVertex3f(0,0,0);
    glVertex3f(Cos(k),0,Sin(k));
    glVertex3f(Cos(k+deg),0,Sin(k+deg));
  }
  glEnd();

  glPopMatrix();
}