ATMOSPHE.CXX

/* 
 * (c) Copyright 1993, Silicon Graphics, Inc. 
 *               1993-1995 Microsoft Corporation 
 * 
 * ALL RIGHTS RESERVED 
 * 
 * Please refer to OpenGL/readme.txt for additional information 
 * 
 */ 
 
#include "glos.h" 
 
#include <GL/glu.h> 
 
#ifdef X11 
#include <GL/glx.h> 
#endif 
 
#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
 
#ifdef WIN32 
#include "stonehen.h" 
#endif 
 
#define ATMOSPHERE_EXTERN 
#include "atmosphe.h" 
 
const Weather clear("Clear", 0.); 
const Weather foggy("Foggy", .04, .5, white, Color(.6, .6, 1), white); 
const Weather very_foggy("Very Foggy", .25, .5, white, white, white); 
const Weather rainy("Rainy", .01, 1., black, Color(.35, .35, .35), black); 
 
Weather weathers[nweathers] = {clear, foggy, very_foggy, rainy}; 
 
const float root3_2 = sqrt(3.) / 2.; 
 
inline float clamp(float a, float min = 0, float max = 1) 
{ 
  if (a < min) return min; 
  else if (a > max) return max; 
  else return a; 
} 
 
Weather::Weather() 
{ 
  strcpy(name, "No name"); 
  fog_density = 0; 
  fog_color = white; 
  fog_spread = 1; 
  sun_brightness = 1; 
  light_sun = GL_LIGHT0; 
  light_ambient = GL_LIGHT1; 
  sky_top = blue; 
  sky_bottom = white; 
} 
 
Weather::Weather(const char *n, GLfloat fd, GLfloat fs, Color fc,  
 Color s1, Color s2, GLfloat sb, 
 GLenum ls, GLenum la) 
{ 
  strcpy(name, n); 
  fog_density = fd; 
  fog_color = fc; 
  fog_spread = fs; 
  sun_brightness = sb; 
  light_sun = ls; 
  light_ambient = la; 
  sky_top = s1; 
  sky_bottom = s2; 
} 
 
Weather::~Weather() 
{ 
} 
 
Weather Weather::operator=(Weather a) 
{ 
  strcpy(name, a.name); 
 
  fog_density = a.fog_density; 
  fog_color = a.fog_color; 
  fog_spread = a.fog_spread; 
 
  sun_brightness = a.sun_brightness; 
 
  light_sun = a.light_sun; 
  light_ambient = a.light_ambient; 
 
  sky_top = a.sky_top; 
  sky_bottom = a.sky_bottom; 
 
  return *this; 
} 
 
void Weather::apply(Point sun) 
{ 
  Color c; 
 
  if (fog_density != 0) { 
    glFogf(GL_FOG_DENSITY, fog_density); 
    glFogfv(GL_FOG_COLOR, fog_color.c); 
    glFogi(GL_FOG_MODE, GL_EXP2); 
  } 
  glLightfv(light_sun, GL_AMBIENT, black.c); 
  c = white; 
  c *= sun_brightness; 
  glLightfv(light_sun, GL_DIFFUSE, c.c); 
  glLightfv(light_sun, GL_SPECULAR, white.c); 
  if (sun.pt[2] >= 0.0) glEnable(light_sun); 
  else glDisable(light_sun); 
 
  c = white; 
  c *= .25; 
  glLightfv(light_ambient, GL_AMBIENT, c.c); 
  glLightfv(light_ambient, GL_DIFFUSE, black.c); 
  glLightfv(light_ambient, GL_SPECULAR, black.c); 
  glEnable(light_ambient); 
} 
 
void Weather::draw_sky(Point sun) 
{ 
  Point p; 
  float c; 
  Color bottom, top; 
 
  if (sun.pt[2] >= .5) c = 1.; 
  else if (sun.pt[2] >= -.5)  
    c = sqrt(1. - sun.pt[2]*sun.pt[2])*.5 + sun.pt[2]*root3_2; 
  else c = 0; 
 
  bottom = sky_bottom * c; 
  top = sky_top * c; 
 
  /* This is drawn as a far-away quad */ 
  glBegin(GL_QUADS); 
  glColor3fv(bottom.c); 
  glVertex3f(-1, -1, -1); 
  glVertex3f(1, -1, -1); 
  glColor3fv(top.c); 
  glVertex3f(1, 1, -1); 
  glVertex3f(-1, 1, -1); 
  glEnd(); 
} 
 
GLfloat Weather::shadow_blur() 
{ 
  return clamp(fog_density * 10.); 
}