/*
 * This program is under the GNU GPL.
 * Use at your own risk.
 *
 * written by David Bucciarelli (tech.hmw@plus.it)
 *            Humanware s.r.l.
 */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include <string.h>

#ifdef WIN32
#include <windows.h>
#include <mmsystem.h>
#endif

#include <GL/glut.h>
#include "readtex.h"

#ifdef XMESA
#include "GL/xmesa.h"
static int fullscreen = 1;
#endif

#ifndef M_PI
#define M_PI 3.1415926535
#endif

#define vinit(a,i,j,k) {\
  (a)[0]=i;\
  (a)[1]=j;\
  (a)[2]=k;\
}

#define vinit4(a,i,j,k,w) {\
  (a)[0]=i;\
  (a)[1]=j;\
  (a)[2]=k;\
  (a)[3]=w;\
}


#define vadds(a,dt,b) {\
  (a)[0]+=(dt)*(b)[0];\
  (a)[1]+=(dt)*(b)[1];\
  (a)[2]+=(dt)*(b)[2];\
}

#define vequ(a,b) {\
  (a)[0]=(b)[0];\
  (a)[1]=(b)[1];\
  (a)[2]=(b)[2];\
}

#define vinter(a,dt,b,c) {\
  (a)[0]=(dt)*(b)[0]+(1.0-dt)*(c)[0];\
  (a)[1]=(dt)*(b)[1]+(1.0-dt)*(c)[1];\
  (a)[2]=(dt)*(b)[2]+(1.0-dt)*(c)[2];\
}

#define clamp(a)        ((a) < 0.0 ? 0.0 : ((a) < 1.0 ? (a) : 1.0))

#define vclamp(v) {\
  (v)[0]=clamp((v)[0]);\
  (v)[1]=clamp((v)[1]);\
  (v)[2]=clamp((v)[2]);\
}

static int WIDTH = 640;
static int HEIGHT = 480;

static GLint T0 = 0;
static GLint Frames = 0;
static GLint NiceFog = 1;

#define DIMP 20.0
#define DIMTP 16.0

#define RIDCOL 0.4

#define NUMTREE 50
#define TREEINR 2.5
#define TREEOUTR 8.0

#define AGRAV -9.8

typedef struct
{
   int age;
   float p[3][3];
   float v[3];
   float c[3][4];
}
part;

static float treepos[NUMTREE][3];

static float black[3] = { 0.0, 0.0, 0.0 };
static float blu[3] = { 1.0, 0.2, 0.0 };
static float blu2[3] = { 1.0, 1.0, 0.0 };

static float fogcolor[4] = { 1.0, 1.0, 1.0, 1.0 };

static float q[4][3] = {
   {-DIMP, 0.0, -DIMP},
   {DIMP, 0.0, -DIMP},
   {DIMP, 0.0, DIMP},
   {-DIMP, 0.0, DIMP}
};

static float qt[4][2] = {
   {-DIMTP, -DIMTP},
   {DIMTP, -DIMTP},
   {DIMTP, DIMTP},
   {-DIMTP, DIMTP}
};

static int win = 0;

static int np;
static float eject_r, dt, maxage, eject_vy, eject_vl;
static short shadows;
static float ridtri;
static int fog = 1;
static int help = 1;
static int joyavailable = 0;
static int joyactive = 0;

static part *p;

static GLuint groundid;
static GLuint treeid;

static float obs[3] = { 2.0, 1.0, 0.0 };
static float dir[3];
static float v = 0.0;
static float alpha = -84.0;
static float beta = 90.0;

static float
vrnd(void)
{
   return (((float) rand()) / RAND_MAX);
}

static void
setnewpart(part * p)
{
   float a, v[3], *c;

   p->age = 0;

   a = vrnd() * 3.14159265359 * 2.0;

   vinit(v, sin(a) * eject_r * vrnd(), 0.15, cos(a) * eject_r * vrnd());
   vinit(p->p[0], v[0] + vrnd() * ridtri, v[1] + vrnd() * ridtri,
	 v[2] + vrnd() * ridtri);
   vinit(p->p[1], v[0] + vrnd() * ridtri, v[1] + vrnd() * ridtri,
	 v[2] + vrnd() * ridtri);
   vinit(p->p[2], v[0] + vrnd() * ridtri, v[1] + vrnd() * ridtri,
	 v[2] + vrnd() * ridtri);

   vinit(p->v, v[0] * eject_vl / (eject_r / 2),
	 vrnd() * eject_vy + eject_vy / 2, v[2] * eject_vl / (eject_r / 2));

   c = blu;

   vinit4(p->c[0], c[0] * ((1.0 - RIDCOL) + vrnd() * RIDCOL),
	  c[1] * ((1.0 - RIDCOL) + vrnd() * RIDCOL),
	  c[2] * ((1.0 - RIDCOL) + vrnd() * RIDCOL), 1.0);
   vinit4(p->c[1], c[0] * ((1.0 - RIDCOL) + vrnd() * RIDCOL),
	  c[1] * ((1.0 - RIDCOL) + vrnd() * RIDCOL),
	  c[2] * ((1.0 - RIDCOL) + vrnd() * RIDCOL), 1.0);
   vinit4(p->c[2], c[0] * ((1.0 - RIDCOL) + vrnd() * RIDCOL),
	  c[1] * ((1.0 - RIDCOL) + vrnd() * RIDCOL),
	  c[2] * ((1.0 - RIDCOL) + vrnd() * RIDCOL), 1.0);
}

static void
setpart(part * p)
{
   float fact;

   if (p->p[0][1] < 0.1) {
      setnewpart(p);
      return;
   }

   p->v[1] += AGRAV * dt;

   vadds(p->p[0], dt, p->v);
   vadds(p->p[1], dt, p->v);
   vadds(p->p[2], dt, p->v);

   p->age++;

   if ((p->age) > maxage) {
      vequ(p->c[0], blu2);
      vequ(p->c[1], blu2);
      vequ(p->c[2], blu2);
   }
   else {
      fact = 1.0 / maxage;
      vadds(p->c[0], fact, blu2);
      vclamp(p->c[0]);
      p->c[0][3] = fact * (maxage - p->age);

      vadds(p->c[1], fact, blu2);
      vclamp(p->c[1]);
      p->c[1][3] = fact * (maxage - p->age);

      vadds(p->c[2], fact, blu2);
      vclamp(p->c[2]);
      p->c[2][3] = fact * (maxage - p->age);
   }
}

static void
drawtree(float x, float y, float z)
{
   glBegin(GL_QUADS);
   glTexCoord2f(0.0, 0.0);
   glVertex3f(x - 1.5, y + 0.0, z);

   glTexCoord2f(1.0, 0.0);
   glVertex3f(x + 1.5, y + 0.0, z);

   glTexCoord2f(1.0, 1.0);
   glVertex3f(x + 1.5, y + 3.0, z);

   glTexCoord2f(0.0, 1.0);
   glVertex3f(x - 1.5, y + 3.0, z);


   glTexCoord2f(0.0, 0.0);
   glVertex3f(x, y + 0.0, z - 1.5);

   glTexCoord2f(1.0, 0.0);
   glVertex3f(x, y + 0.0, z + 1.5);

   glTexCoord2f(1.0, 1.0);
   glVertex3f(x, y + 3.0, z + 1.5);

   glTexCoord2f(0.0, 1.0);
   glVertex3f(x, y + 3.0, z - 1.5);

   glEnd();

}

static void
calcposobs(void)
{
   dir[0] = sin(alpha * M_PI / 180.0);
   dir[2] = cos(alpha * M_PI / 180.0) * sin(beta * M_PI / 180.0);
   dir[1] = cos(beta * M_PI / 180.0);

   if (dir[0] < 1.0e-5 && dir[0] > -1.0e-5)
      dir[0] = 0;
   if (dir[1] < 1.0e-5 && dir[1] > -1.0e-5)
      dir[1] = 0;
   if (dir[2] < 1.0e-5 && dir[2] > -1.0e-5)
      dir[2] = 0;

   obs[0] += v * dir[0];
   obs[1] += v * dir[1];
   obs[2] += v * dir[2];
}

static void
printstring(void *font, char *string)
{
   int len, i;

   len = (int) strlen(string);
   for (i = 0; i < len; i++)
      glutBitmapCharacter(font, string[i]);
}

static void
reshape(int width, int height)
{
   WIDTH = width;
   HEIGHT = height;
   glViewport(0, 0, (GLint) width, (GLint) height);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluPerspective(70.0, width / (float) height, 0.1, 30.0);

   glMatrixMode(GL_MODELVIEW);
}

static void
printhelp(void)
{
   glColor4f(0.0, 0.0, 0.0, 0.5);
   glRecti(40, 40, 600, 440);

   glColor3f(1.0, 0.0, 0.0);
   glRasterPos2i(300, 420);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "Help");

   glRasterPos2i(60, 390);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "h - Toggle Help");

   glRasterPos2i(60, 360);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "t - Increase particle size");
   glRasterPos2i(60, 330);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "T - Decrease particle size");

   glRasterPos2i(60, 300);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "r - Increase emission radius");
   glRasterPos2i(60, 270);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "R - Decrease emission radius");

   glRasterPos2i(60, 240);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "f - Toggle Fog");
   glRasterPos2i(60, 210);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "s - Toggle shadows");
   glRasterPos2i(60, 180);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "Arrow Keys - Rotate");
   glRasterPos2i(60, 150);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "a - Increase velocity");
   glRasterPos2i(60, 120);
   printstring(GLUT_BITMAP_TIMES_ROMAN_24, "z - Decrease velocity");

   glRasterPos2i(60, 90);
   if (joyavailable)
      printstring(GLUT_BITMAP_TIMES_ROMAN_24,
		  "j - Toggle jostick control (Joystick control available)");
   else
      printstring(GLUT_BITMAP_TIMES_ROMAN_24,
		  "(No Joystick control available)");
}

static void
dojoy(void)
{
#ifdef WIN32
   static UINT max[2] = { 0, 0 };
   static UINT min[2] = { 0xffffffff, 0xffffffff }, center[2];
   MMRESULT res;
   JOYINFO joy;

   res = joyGetPos(JOYSTICKID1, &joy);

   if (res == JOYERR_NOERROR) {
      joyavailable = 1;

      if (max[0] < joy.wXpos)
	 max[0] = joy.wXpos;
      if (min[0] > joy.wXpos)
	 min[0] = joy.wXpos;
      center[0] = (max[0] + min[0]) / 2;

      if (max[1] < joy.wYpos)
	 max[1] = joy.wYpos;
      if (min[1] > joy.wYpos)
	 min[1] = joy.wYpos;
      center[1] = (max[1] + min[1]) / 2;

      if (joyactive) {
	 if (fabs(center[0] - (float) joy.wXpos) > 0.1 * (max[0] - min[0]))
	    alpha +=
	       2.5 * (center[0] - (float) joy.wXpos) / (max[0] - min[0]);
	 if (fabs(center[1] - (float) joy.wYpos) > 0.1 * (max[1] - min[1]))
	    beta += 2.5 * (center[1] - (float) joy.wYpos) / (max[1] - min[1]);

	 if (joy.wButtons & JOY_BUTTON1)
	    v += 0.01;
	 if (joy.wButtons & JOY_BUTTON2)
	    v -= 0.01;
      }
   }
   else
      joyavailable = 0;
#endif
}

static void
drawfire(void)
{
   static char frbuf[80] = "";
   int j;
   static double t0 = -1.;
   double t = glutGet(GLUT_ELAPSED_TIME) / 1000.0;
   if (t0 < 0.0)
      t0 = t;
   dt = (t - t0) * 1.0;
   t0 = t;

   dojoy();

   if (NiceFog)
      glHint(GL_FOG_HINT, GL_NICEST);
   else
      glHint(GL_FOG_HINT, GL_DONT_CARE);

   glEnable(GL_DEPTH_TEST);

   if (fog)
      glEnable(GL_FOG);
   else
      glDisable(GL_FOG);

   glDepthMask(GL_TRUE);
   glClearColor(1.0, 1.0, 1.0, 1.0);
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

   glPushMatrix();
   calcposobs();
   gluLookAt(obs[0], obs[1], obs[2],
	     obs[0] + dir[0], obs[1] + dir[1], obs[2] + dir[2],
	     0.0, 1.0, 0.0);

   glColor4f(1.0, 1.0, 1.0, 1.0);

   glEnable(GL_TEXTURE_2D);

   glBindTexture(GL_TEXTURE_2D, groundid);
#if 1
   glBegin(GL_QUADS);
   glTexCoord2fv(qt[0]);
   glVertex3fv(q[0]);
   glTexCoord2fv(qt[1]);
   glVertex3fv(q[1]);
   glTexCoord2fv(qt[2]);
   glVertex3fv(q[2]);
   glTexCoord2fv(qt[3]);
   glVertex3fv(q[3]);
   glEnd();
#else
   /* Subdivide the ground into a bunch of quads.  This improves fog
    * if GL_FOG_HINT != GL_NICEST
    */
   {
      float x, y;
      float dx = 1.0, dy = 1.0;
      glBegin(GL_QUADS);
      for (y = -DIMP; y < DIMP; y += 1.0) {
         for (x = -DIMP; x < DIMP; x += 1.0) {
            glTexCoord2f(0, 0);   glVertex3f(x, 0, y);
            glTexCoord2f(1, 0);   glVertex3f(x+dx, 0, y);
            glTexCoord2f(1, 1);   glVertex3f(x+dx, 0, y+dy);
            glTexCoord2f(0, 1);   glVertex3f(x, 0, y+dy);
         }
      }
      glEnd();
   }
#endif


   glEnable(GL_ALPHA_TEST);
   glAlphaFunc(GL_GEQUAL, 0.9);

   glBindTexture(GL_TEXTURE_2D, treeid);
   for (j = 0; j < NUMTREE; j++)
      drawtree(treepos[j][0], treepos[j][1], treepos[j][2]);

   glDisable(GL_TEXTURE_2D);
   glDepthMask(GL_FALSE);
   glDisable(GL_ALPHA_TEST);

   if (shadows) {
      glBegin(GL_TRIANGLES);
      for (j = 0; j < np; j++) {
	 glColor4f(black[0], black[1], black[2], p[j].c[0][3]);
	 glVertex3f(p[j].p[0][0], 0.1, p[j].p[0][2]);

	 glColor4f(black[0], black[1], black[2], p[j].c[1][3]);
	 glVertex3f(p[j].p[1][0], 0.1, p[j].p[1][2]);

	 glColor4f(black[0], black[1], black[2], p[j].c[2][3]);
	 glVertex3f(p[j].p[2][0], 0.1, p[j].p[2][2]);
      }
      glEnd();
   }

   glBegin(GL_TRIANGLES);
   for (j = 0; j < np; j++) {
      glColor4fv(p[j].c[0]);
      glVertex3fv(p[j].p[0]);

      glColor4fv(p[j].c[1]);
      glVertex3fv(p[j].p[1]);

      glColor4fv(p[j].c[2]);
      glVertex3fv(p[j].p[2]);

      setpart(&p[j]);
   }
   glEnd();

   glDisable(GL_TEXTURE_2D);
   glDisable(GL_ALPHA_TEST);
   glDisable(GL_DEPTH_TEST);
   glDisable(GL_FOG);

   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glOrtho(-0.5, 639.5, -0.5, 479.5, -1.0, 1.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();

   glColor3f(1.0, 0.0, 0.0);
   glRasterPos2i(10, 10);
   printstring(GLUT_BITMAP_HELVETICA_18, frbuf);
   glRasterPos2i(370, 470);
   printstring(GLUT_BITMAP_HELVETICA_10,
	       "Fire V1.5 Written by David Bucciarelli (tech.hmw@plus.it)");

   if (help)
      printhelp();

   reshape(WIDTH, HEIGHT);
   glPopMatrix();

   glutSwapBuffers();

   Frames++;
   {
      GLint t = glutGet(GLUT_ELAPSED_TIME);
      if (t - T0 >= 2000) {
         GLfloat seconds = (t - T0) / 1000.0;
         GLfloat fps = Frames / seconds;
         sprintf(frbuf, "Frame rate: %f", fps);
         T0 = t;
         Frames = 0;
      }
   }
}


static void
idle(void)
{
   glutPostRedisplay();
}


static void
special(int key, int x, int y)
{
   switch (key) {
   case GLUT_KEY_LEFT:
      alpha += 2.0;
      break;
   case GLUT_KEY_RIGHT:
      alpha -= 2.0;
      break;
   case GLUT_KEY_DOWN:
      beta -= 2.0;
      break;
   case GLUT_KEY_UP:
      beta += 2.0;
      break;
   }
   glutPostRedisplay();
}

static void
key(unsigned char key, int x, int y)
{
   switch (key) {
   case 27:
      exit(0);
      break;

   case 'a':
      v += 0.0005;
      break;
   case 'z':
      v -= 0.0005;
      break;

   case 'j':
      joyactive = (!joyactive);
      break;
   case 'h':
      help = (!help);
      break;
   case 'f':
      fog = (!fog);
      break;
   case 's':
      shadows = !shadows;
      break;
   case 'R':
      eject_r -= 0.03;
      break;
   case 'r':
      eject_r += 0.03;
      break;
   case 't':
      ridtri += 0.005;
      break;
   case 'T':
      ridtri -= 0.005;
      break;
#ifdef XMESA
   case ' ':
      XMesaSetFXmode(fullscreen ? XMESA_FX_FULLSCREEN : XMESA_FX_WINDOW);
      fullscreen = (!fullscreen);
      break;
#endif
   case 'n':
      NiceFog = !NiceFog;
      printf("NiceFog %d\n", NiceFog);
      break;
   }
   glutPostRedisplay();
}

static void
inittextures(void)
{
   GLenum gluerr;
   GLubyte tex[128][128][4];

   glGenTextures(1, &groundid);
   glBindTexture(GL_TEXTURE_2D, groundid);

   glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
   if (!LoadRGBMipmaps("../images/s128.rgb", GL_RGB)) {
      fprintf(stderr, "Error reading a texture.\n");
      exit(-1);
   }

   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
		   GL_LINEAR_MIPMAP_LINEAR);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

   glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

   glGenTextures(1, &treeid);
   glBindTexture(GL_TEXTURE_2D, treeid);

   if (1)
   {
      int w, h;
      GLenum format;
      int x, y;
      GLubyte *image = LoadRGBImage("../images/tree3.rgb", &w, &h, &format);

      if (!image) {
	 fprintf(stderr, "Error reading a texture.\n");
	 exit(-1);
      }

      for (y = 0; y < 128; y++)
	 for (x = 0; x < 128; x++) {
	    tex[x][y][0] = image[(y + x * 128) * 3];
	    tex[x][y][1] = image[(y + x * 128) * 3 + 1];
	    tex[x][y][2] = image[(y + x * 128) * 3 + 2];
	    if ((tex[x][y][0] == tex[x][y][1]) &&
		(tex[x][y][1] == tex[x][y][2]) && (tex[x][y][2] == 255))
	       tex[x][y][3] = 0;
	    else
	       tex[x][y][3] = 255;
	 }

      if ((gluerr = gluBuild2DMipmaps(GL_TEXTURE_2D, 4, 128, 128, GL_RGBA,
				      GL_UNSIGNED_BYTE, (GLvoid *) (tex)))) {
	 fprintf(stderr, "GLULib%s\n", (char *) gluErrorString(gluerr));
	 exit(-1);
      }
   }
   else {
      if (!LoadRGBMipmaps("../images/tree2.rgba", GL_RGBA)) {
	 fprintf(stderr, "Error reading a texture.\n");
	 exit(-1);
      }
   }

   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
		   GL_LINEAR_MIPMAP_LINEAR);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

   glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
}

static void
inittree(void)
{
   int i;
   float dist;

   for (i = 0; i < NUMTREE; i++)
      do {
	 treepos[i][0] = vrnd() * TREEOUTR * 2.0 - TREEOUTR;
	 treepos[i][1] = 0.0;
	 treepos[i][2] = vrnd() * TREEOUTR * 2.0 - TREEOUTR;
	 dist =
	    sqrt(treepos[i][0] * treepos[i][0] +
		 treepos[i][2] * treepos[i][2]);
      } while ((dist < TREEINR) || (dist > TREEOUTR));
}

int
main(int ac, char **av)
{
   int i;

   fprintf(stderr,
	   "Fire V1.5\nWritten by David Bucciarelli (tech.hmw@plus.it)\n");

   /* Default settings */

   np = 800;
   eject_r = -0.65;
   dt = 0.015;
   eject_vy = 4;
   eject_vl = 1;
   shadows = 1;
   ridtri = 0.25;

   maxage = 1.0 / dt;

   if (ac == 2)
      np = atoi(av[1]);

   if (ac == 4) {
      WIDTH = atoi(av[2]);
      HEIGHT = atoi(av[3]);
   }

   glutInitWindowSize(WIDTH, HEIGHT);
   glutInit(&ac, av);

   glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);

   if (!(win = glutCreateWindow("Fire"))) {
      fprintf(stderr, "Error opening a window.\n");
      exit(-1);
   }

   reshape(WIDTH, HEIGHT);

   inittextures();

   glShadeModel(GL_FLAT);
   glEnable(GL_DEPTH_TEST);

   glEnable(GL_BLEND);
   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

   glEnable(GL_FOG);
   glFogi(GL_FOG_MODE, GL_EXP);
   glFogfv(GL_FOG_COLOR, fogcolor);
   glFogf(GL_FOG_DENSITY, 0.1);

   p = (part *) malloc(sizeof(part) * np);

   for (i = 0; i < np; i++)
      setnewpart(&p[i]);

   inittree();

   glutKeyboardFunc(key);
   glutSpecialFunc(special);
   glutDisplayFunc(drawfire);
   glutIdleFunc(idle);
   glutReshapeFunc(reshape);
   glutMainLoop();

   return (0);
}