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

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

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

#include <GL/glut.h>
#include <GL/gl.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] =((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(-80.F + dx,-60.F + dy,-420.F + dz);
  glCallList(SPHERE);
  glPopMatrix();
  glPushMatrix();
  glTranslatef(-20.F,-80.F,-600.F);
  glCallList(CONE);
  glPopMatrix();
  if( glGetError() )
    printf("Oops! I screwed up my OpenGL calls somewhere\n");
  glFlush();
}

enum {NONE,FIELD};

int rendermode = NONE;

void menu(int selection) {
  rendermode = selection;
  glutPostRedisplay();
}

GLdouble focus = 420.;

void redraw() {
  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();
  glutSwapBuffers();
}

void key(unsigned char key,int x,int y) {
  if(key == '\033')
    exit(0);
}

const int TEXDIM = 256;

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  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;
  glutInitWindowSize(300,300);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_ACCUM|GLUT_DOUBLE);
  glutCreateWindow("Motion blur");
  glutDisplayFunc(redraw);
  glutKeyboardFunc(key);
  glutCreateMenu(menu);
  glutAddMenuEntry("Normal",NONE);
  glutAddMenuEntry("Motion Blur",FIELD);
  glutAttachMenu(GLUT_RIGHT_BUTTON);
  glMatrixMode(GL_PROJECTION);
  glFrustum(-FRUSTDIM,FRUSTDIM,-FRUSTDIM,FRUSTDIM,FRUSTNEAR,FRUSTFAR); 
  glMatrixMode(GL_MODELVIEW);
  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);
  glutMainLoop();
  return(0);
}