/* Just messing around with OpenGL
 *
 * Copyright Clint Byrum, 2002. All Rights Reserved.
 *
 * This code is covered under the GNU General Public
 * License, v2.0 or later.
 * 
*/

#include <GL/glut.h>
#include <GL/gl.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define DISPLAY_DELAY 50
#define MOVE_FACTOR 8.2
#define MASS1_SIZE 250

#define XSTART 450.0
#define YSTART 450.0
#define ZSTART 0.0

#define WORLDX 640.0
#define WORLDY 480.0 
#define WORLDZ 150.0


struct toyMass {
  int vcount;
  GLfloat *vertexes;
  GLfloat *colors;
};

void toyDisplayWin(void);
void toyTimerFunc(int value);
struct toyMass *toyMakeLots(int howmany,struct toyMass *mass);
void toyDisplayMass(struct toyMass *mass);
GLfloat toyRand(GLfloat low,GLfloat high);

/* Global mass */  
struct toyMass *onemass;

static GLfloat lastpos= 20;
static GLfloat lastpos2=40;

int main(int argcp, char **argv) {
  int winhndl;
  glutInitWindowSize(640,480);
  glutInitWindowPosition(0,0);


  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);

  glutInit(&argcp, argv);

  winhndl=glutCreateWindow("My god this is idiotic");
  glutSetCursor(GLUT_CURSOR_CROSSHAIR);

  glClearColor(0.0,0.0,0.0,0.0);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0.0,WORLDX,0.0,WORLDY,-WORLDZ,WORLDZ);
 
  glutDisplayFunc(toyDisplayWin);
  glutTimerFunc(DISPLAY_DELAY,toyTimerFunc,0);


  srand(time(NULL));
  /*fprintf(stderr,"time=%d",time(NULL));*/
  
  onemass=malloc(sizeof(struct toyMass));
  if(onemass==NULL) { exit(1); };
  onemass->vertexes=malloc(sizeof(GLfloat)*MASS1_SIZE);
  if(onemass->vertexes==NULL) { exit(1); };
  onemass->colors=malloc(sizeof(GLfloat)*MASS1_SIZE);
  if(onemass->colors==NULL) { exit(1); };

  toyMakeLots(MASS1_SIZE,onemass);
  
  /*fprintf(stderr,"Calling glutMainLoop\n");*/
  glutMainLoop();

  sleep(1);

  return 0;
}

void toyDisplayWin(void) {

  GLdouble  sphereRadius=30;
  GLint     sphereSlices=30;
  GLint     sphereStacks=30;

  GLfloat oldpos,diff;
  
  GLfloat r1[3],r2[3],r3[3],r4[3];
  
  diff=((-1.0*MOVE_FACTOR)+(2.0*MOVE_FACTOR)*rand()/(RAND_MAX+1.0));
  lastpos=lastpos+diff;
  
  r1[0]=20.0;r1[1]=40.0+lastpos;r1[2]=0.0;
  r2[0]=40.0;
  
  diff=((-1.0*MOVE_FACTOR)+(2.0*MOVE_FACTOR)*rand()/(RAND_MAX+1.0));
  lastpos=lastpos+diff;
  r2[1]=lastpos;
  r2[2]=lastpos-(lastpos*0.4);

  r3[0]=40.0+lastpos;r3[1]=80.0;r3[2]=0.0;
  /*r4[0]=20.0;*/
  
  oldpos=lastpos;
  diff=((-1.0*MOVE_FACTOR)+(2.0*MOVE_FACTOR)*rand()/(RAND_MAX+1.0));
  lastpos=lastpos+diff;
  r4[0]=lastpos;
  r4[1]=80.0;
  r4[2]=(-1.0+20.0*rand()/(RAND_MAX+1.0));;
 
  /*fprintf(stderr,"In toyDisplayWin [%f]\n",r4[0]);*/
  
  glClear(GL_COLOR_BUFFER_BIT);

  glColor3f(1.0,0.0,0.0);
  
  /*
  glBegin(GL_POLYGON); 
  glVertex3f(2.0, 4.0, 0.0); 
  glColor3f(0.0,1.0,0.0);
  glVertex3f(8.0, 4.0, 0.0);
  glColor3f(0.0,0.0,1.0);
  glVertex3f(8.0, 6.0, 0.0); 
  glVertex3f(2.0, 6.0, 0.0); 
  glEnd(); 
  */
  
  /*glutWireSphere(sphereRadius,sphereSlices,sphereStacks);*/

  glColor3f(0.0,1.0,0.0);

  /*
  glBegin(GL_POLYGON);
  */
  /*
  glVertex3f(20.0,40.0,0.0);
  glVertex3f(40.0,40.0,0.0);
  glVertex3f(40.0,80.0,0.0);
  glVertex3f(20.0,80.0,0.0);
  */
  /*
  glVertex3fv(r1);
  glColor3f(1.0,0.5,0.0);
  glVertex3fv(r2);
  glVertex3fv(r3);
  */
  /*glColor3f(rand()/(RAND_MAX+1.0),0.0,1.0);*/
  /*
  glColor3f(1.0,0.0,1.0);
  glVertex3fv(r4);
  glEnd();
  */

  toyDisplayMass(onemass);

  /*glFlush();*/
  glutSwapBuffers();

  glutTimerFunc(DISPLAY_DELAY,toyTimerFunc,0);
  /*usleep(600);*/ 
}

void toyTimerFunc(int value) {
  /*fprintf(stderr,"In toyTimerFunc\n");*/
  glutPostRedisplay();
}

/* howmany = howmany polygons to make
 * mass = pointer to allocated RAM for masses
 */
struct toyMass *toyMakeLots(int howmany, struct toyMass *mass) {
  int i,vpos;
  GLfloat lastx;
  GLfloat lasty;
  GLfloat lastz;
  GLfloat diff;
  lastx=XSTART+toyRand(0,10);
  lasty=YSTART+toyRand(0,10);
  lastz=ZSTART+toyRand(0,10);
  for(i=0;i<=howmany;i++) {
    /* Move a small amount x, then y, then z */
    vpos=i*3;
    diff=(-1.0*MOVE_FACTOR)+(MOVE_FACTOR*2)*rand()/(RAND_MAX+1.0);
    lastx+=diff;
    mass->vertexes[vpos+0]=lastx;
    mass->colors[vpos+0]=lastx-(lastx*0.9);
    diff=(-1.0*MOVE_FACTOR)+(MOVE_FACTOR*2)*rand()/(RAND_MAX+1.0);
    lasty+=diff;
    mass->vertexes[vpos+1]=lasty;
    mass->colors[vpos+0]=lasty-(lasty*0.9);
    diff=(-1.0*MOVE_FACTOR)+(MOVE_FACTOR*2)*rand()/(RAND_MAX+1.0);
    lastz+=diff;
    mass->vertexes[vpos+2]=lastz;
    mass->colors[vpos+0]=lastz-(lastz*0.9);
    mass->vcount++;
  }
  return mass;
}

void toyDisplayMass(struct toyMass *mass) {
  int i;
  GLfloat tmp[3];
  GLfloat tmpc[4];
  glBegin(GL_POLYGON);
  for(i=0;i<=mass->vcount;i++) {
    tmp[0]=mass->vertexes[i]  +toyRand(0,0.1);
    tmp[1]=mass->vertexes[i+1]+toyRand(0,0.1);
    tmp[2]=mass->vertexes[i+2]+toyRand(0,0.1);
    tmpc[0]=mass->colors[i];
    tmpc[1]=mass->colors[i+1];
    tmpc[2]=mass->colors[i+2];
    tmpc[3]=toyRand(0,1);
    /*fprintf(stderr,"tmpc[3]=%f",tmpc[3]);*/
    /*glColor3f(toyRand(0,3),toyRand(0,3),toyRand(0,3)); */
    /*glColor3f(toyRand(0,0.2),0.25,1.0);*/
    glColor4fv(tmpc);
    glVertex3fv(tmp);
  }
  glEnd();
}

GLfloat toyRand(GLfloat low,GLfloat high) {
  return low+(high*rand()/(RAND_MAX+1.0));
}