/* motionblur.c - by Tom McReynolds, SGI */

/* Using the accumulation buffer for motion blur. */

#include <windows.h>

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glaux.h>

#include <stdio.h>
#include <stdlib.h>

const GLdouble FRUSTDIM = 100.f;
const GLdouble FRUSTNEAR = 320.f;
const GLdouble FRUSTFAR = 660.f;

GLfloat *make_texture(int maxs,int maxt) {
  int s,t;
  static GLfloat *texture;
  texture =(GLfloat *)malloc(maxs * maxt * sizeof(GLfloat));
  for(t = 0; t < maxt; t++) {
    for(s = 0; s < maxs; s++) {
      texture[s + maxs * t] =(float)(((s >> 4) & 0x1) ^((t >> 4) & 0x1)); } }
  return(texture);
}

enum {SPHERE = 1,CONE};

void render(GLfloat dx,GLfloat dy,GLfloat dz) {
  static GLfloat wall_mat[] = {1.f,1.f,1.f,1.f};
  glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
  glMaterialfv(GL_FRONT,GL_AMBIENT_AND_DIFFUSE,wall_mat);
  glEnable(GL_TEXTURE_2D);
  glBegin(GL_QUADS);
  glNormal3f(0.f,1.f,0.f);
  glTexCoord2i(0,0);
  glVertex3f(-100.f,-100.f,-320.f);
  glTexCoord2i(1,0);
  glVertex3f(100.f,-100.f,-320.f);
  glTexCoord2i(1,1);
  glVertex3f(100.f,-100.f,-640.f);
  glTexCoord2i(0,1);
  glVertex3f(-100.f,-100.f,-640.f);
  glEnd();
  glDisable(GL_TEXTURE_2D);
  glBegin(GL_QUADS);
  glNormal3f(1.f,0.f,0.f);
  glVertex3f(-100.f,-100.f,-320.f);
  glVertex3f(-100.f,-100.f,-640.f);
  glVertex3f(-100.f,100.f,-640.f);
  glVertex3f(-100.f,100.f,-320.f);
  glNormal3f(-1.f,0.f,0.f);
  glVertex3f(100.f,-100.f,-320.f);
  glVertex3f(100.f,100.f,-320.f);
  glVertex3f(100.f,100.f,-640.f);
  glVertex3f(100.f,-100.f,-640.f);
  glNormal3f(0.f,-1.f,0.f);
  glVertex3f(-100.f,100.f,-320.f);
  glVertex3f(-100.f,100.f,-640.f);
  glVertex3f(100.f,100.f,-640.f);
  glVertex3f(100.f,100.f,-320.f);
  glNormal3f(0.f,0.f,1.f);
  glVertex3f(-100.f,-100.f,-640.f);
  glVertex3f(100.f,-100.f,-640.f);
  glVertex3f(100.f,100.f,-640.f);
  glVertex3f(-100.f,100.f,-640.f);
  glEnd();
  glPushMatrix();
  glTranslatef(-60.f + dx,-60.f + dy,-420.f + dz);
  glScalef(2.0f,2.0f,2.0f) ;
  glCallList(SPHERE);
  glPopMatrix();
  glPushMatrix();
  glTranslatef(20.f + dx,-80.f + dy,-600.f + dz);
  glScalef(2.0f,2.0f,2.0f) ;
  glCallList(CONE);
  glPopMatrix();
  if( glGetError() )
    printf("Oops! I screwed up my OpenGL calls somewhere\n");
  glFlush();
}

enum {NONE,FIELD};

int rendermode = NONE;

void CALLBACK redraw(void) {
  int i;
  int max;
  GLfloat dx,dy,dz;
  dx =  .5f;
  dy =  1.f;
  dz = -2.f;
  glPushMatrix();
  switch(rendermode) {
    case NONE  : render(0.f,0.f,0.f);
                 break;
    case FIELD : max = 16;
                 glClear(GL_ACCUM_BUFFER_BIT);
                 for ( i = 0 ; i < max ; i++) {
                   render(dx * i,dy * i,dz * i);
                   glAccum(GL_ACCUM,1.f/max); } 
                 glAccum(GL_RETURN,1.f);
                 break; }
  glPopMatrix();
  auxSwapBuffers();
}

const int TEXDIM = 256;

void CALLBACK myReshape(int w,int h) { 
  glViewport(0,0,w,h); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity(); 
  glFrustum(-FRUSTDIM,FRUSTDIM,-FRUSTDIM,FRUSTDIM,FRUSTNEAR,FRUSTFAR); 
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity(); 
} 
  
void CALLBACK keySpace(void) {
  if ( rendermode == NONE )
    rendermode = FIELD ;
    else
    rendermode = NONE ;
  redraw();
}

void init(void) {
  GLfloat *tex;
  static GLfloat lightpos[] = {50.f,50.f,-320.f,1.f};
  static GLfloat sphere_mat[] = {1.f,.5f,0.f,1.f};
  static GLfloat cone_mat[] = {0.f,.5f,1.f,1.f};
  GLUquadricObj *sphere,*cone,*base;
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glLightfv(GL_LIGHT0,GL_POSITION,lightpos);
  glCullFace(GL_BACK);
  glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
  glNewList(SPHERE,GL_COMPILE);
  sphere = gluNewQuadric();
  glMaterialfv(GL_FRONT,GL_AMBIENT_AND_DIFFUSE,sphere_mat);
  gluSphere(sphere,20.f,20,20);
  gluDeleteQuadric(sphere);
  glEndList();
  glNewList(CONE,GL_COMPILE);
  cone = gluNewQuadric();
  base = gluNewQuadric();
  glRotatef(-90.f,1.f,0.f,0.f);
  glMaterialfv(GL_FRONT,GL_AMBIENT_AND_DIFFUSE,cone_mat);
  gluDisk(base,0.,20.,20,1);
  gluCylinder(cone,20.,0.,60.,20,20);
  gluDeleteQuadric(cone);
  gluDeleteQuadric(base);
  glEndList();
  tex = make_texture(TEXDIM,TEXDIM);
  glTexImage2D(GL_TEXTURE_2D,0,1,TEXDIM,TEXDIM,0,GL_RED,GL_FLOAT,tex);
  free(tex);
}

void main(void) {
  auxInitDisplayMode(AUX_DOUBLE|AUX_RGBA|AUX_DEPTH|AUX_ACCUM);
  auxInitPosition(0,0,300,300);
  auxInitWindow("Motion blur") ;
  init();
  auxKeyFunc(AUX_SPACE,keySpace) ;
  auxReshapeFunc(myReshape);
  auxMainLoop(redraw);
}