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

/* Compositing images that include depth information. */

/* To use this program, you select a region of the "room" scene by
   rubber-banding the region with the left mouse button.  Once a
   region is selected, position the region with the middle mouse
   button.  The region will be composited using the region image and
   the region's depth information.  With the right mouse button, you
   can shift the region's depth values nearer or further away. */

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

/* Create a single component texture map */
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;
}

GLboolean stencil = GL_TRUE;

/* ARGSUSED1 */
void 
key(unsigned char key, int x, int y)
{
  switch (key) {
  case 't':            /* toggle using stencil */
    if (stencil == GL_TRUE)
      stencil = GL_FALSE;
    else
      stencil = GL_TRUE;
    glutPostRedisplay();
    break;
  case '\033':
    exit(0);
    break;
  }
}

enum {
  SPHERE = 1, CONE
};
enum {
  X, Y, Z
};

int startx, starty;
int wid, ht;
int oldwid = 0, oldht = 0;

const int WINDIM = 512;
const GLfloat FRUSTDIM = 110.f;
const GLfloat FRUSTNEAR = 320.f;
const GLfloat FRUSTFAR = 540.f;
const GLfloat FRUSTDIFF = 540.f - 320.f;

GLboolean drawmode = GL_FALSE;
GLboolean depthmode = GL_FALSE;
GLboolean rubberbandmode = GL_FALSE;
GLfloat *color;
GLfloat *depth;
GLfloat depthbias = 0.f;
GLfloat raspos[] =
{0.f, 0.f, -430.f};

int winWidth = 512;
int winHeight = 512;

GLfloat sx = 0;
GLfloat sy = 0;

/* Overlay Stuff */
int transparent;
int red;
int overlaySupport = 0;

void
setRasterPosXY(int x, int y)
{
  raspos[X] = (x - winWidth / 2) * sx;
  raspos[Y] = (y - winHeight / 2) * sy;

  glRasterPos3fv(raspos);

  glutPostRedisplay();
}

void
setRasterPosZ(int y)
{
  raspos[Z] = -(FRUSTNEAR + y * FRUSTDIFF / winHeight);

  depthbias = (y - winHeight / 2.f) / winHeight;

  glRasterPos3fv(raspos);

  glutPostRedisplay();
}

void
motion(int x, int y)
{
  y = winHeight - y;
  if (drawmode)
    setRasterPosXY(x, y);

  if (rubberbandmode) {
    wid = x - startx;
    ht = y - starty;
    if (overlaySupport) glutPostOverlayRedisplay();
  }
  if (depthmode)
    setRasterPosZ(y);
}

/* redraw function for overlay: used to show selected region */
void
overlay(void)
{
  if (glutLayerGet(GLUT_OVERLAY_DAMAGED)) {
    glClear(GL_COLOR_BUFFER_BIT);
  } else {
    glIndexi(transparent);
    glBegin(GL_LINE_LOOP);
    glVertex2i(startx, starty);
    glVertex2i(startx + oldwid, starty);
    glVertex2i(startx + oldwid, starty + oldht);
    glVertex2i(startx, starty + oldht);
    glEnd();
  }

  glIndexi(red);
  glBegin(GL_LINE_LOOP);
  glVertex2i(startx, starty);
  glVertex2i(startx + wid, starty);
  glVertex2i(startx + wid, starty + ht);
  glVertex2i(startx, starty + ht);
  glEnd();

  oldwid = wid;
  oldht = ht;

  glFlush();
}

/* used to get current width and height of viewport */
void
reshape(int wid, int ht)
{
  if (overlaySupport) {
    glutUseLayer(GLUT_OVERLAY);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, wid, 0, ht);  /* 1 to 1 with window */
    glMatrixMode(GL_MODELVIEW);
    glViewport(0, 0, wid, ht);
  }

  glutUseLayer(GLUT_NORMAL);
  glViewport((GLint) (-wid * .1), (GLint) (-ht * .1),
    (GLuint) (wid * 1.2), (GLuint) (ht * 1.2));

  winWidth = wid;
  winHeight = ht;

  sx = 2 * FRUSTDIM / (winWidth * 1.2);
  sy = 2 * FRUSTDIM / (winHeight * 1.2);
}

void
mouse(int button, int state, int x, int y)
{
  y = winHeight - y;    /* flip y orientation */
  if (state == GLUT_DOWN)
    switch (button) {
    case GLUT_LEFT_BUTTON:  /* select an image */
      startx = x;
      starty = y;
      wid = 0;
      ht = 0;
      rubberbandmode = GL_TRUE;
      if (overlaySupport) glutShowOverlay();
      break;
    case GLUT_MIDDLE_BUTTON:
      glutUseLayer(GLUT_NORMAL);
      if (color && depth) {
        drawmode = GL_TRUE;
        setRasterPosXY(x, y);
      }
      break;
    case GLUT_RIGHT_BUTTON:  /* change depth */
      glutUseLayer(GLUT_NORMAL);
      if (color && depth) {
        depthmode = GL_TRUE;
        setRasterPosZ(y);
      }
      break;
  } else                /* GLUT_UP */
    switch (button) {
    case GLUT_LEFT_BUTTON:
      rubberbandmode = GL_FALSE;
      if (overlaySupport) glutHideOverlay();
      wid = x - startx;
      ht = y - starty;
      if (wid < 0) {
        wid = -wid;
        startx = x;
      }
      if (ht < 0) {
        ht = -ht;
        starty = y;
      }
      color = (GLfloat *) realloc(color, wid * ht * 3 * sizeof(GLfloat));
      depth = (GLfloat *) realloc(depth, wid * ht * sizeof(GLfloat));

      glutUseLayer(GLUT_NORMAL);
      glReadPixels(startx, starty, wid, ht, GL_RGB, GL_FLOAT, color);
      glReadPixels(startx, starty, wid, ht, GL_DEPTH_COMPONENT, GL_FLOAT,
        depth);
      break;
    case GLUT_MIDDLE_BUTTON:
      drawmode = GL_FALSE;
      break;
    case GLUT_RIGHT_BUTTON:  /* change depth */
      depthmode = GL_FALSE;
      break;
    }
}

/* Called when window needs to be redrawn */
void
redraw(void)
{
  /* material properties for objects in scene */
  static GLfloat wall_mat[] =
  {1.f, 1.f, 1.f, 1.f};

  glutUseLayer(GLUT_NORMAL);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

  /* Note: wall verticies are ordered so they are all front facing this lets
     me do back face culling to speed things up. */

  glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, wall_mat);

  /* floor */
  /* make the floor textured */
  glEnable(GL_TEXTURE_2D);

  /* Since we want to turn texturing on for floor only, we have to make floor 
     a separate glBegin()/glEnd() sequence. You can't turn texturing on and
     off between begin and end calls */
  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, -520.f);
  glTexCoord2i(0, 1);
  glVertex3f(-100.f, -100.f, -520.f);
  glEnd();

  glDisable(GL_TEXTURE_2D);

  /* walls */

  glBegin(GL_QUADS);
  /* left wall */
  glNormal3f(1.f, 0.f, 0.f);
  glVertex3f(-100.f, -100.f, -320.f);
  glVertex3f(-100.f, -100.f, -520.f);
  glVertex3f(-100.f, 100.f, -520.f);
  glVertex3f(-100.f, 100.f, -320.f);

  /* right wall */
  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, -520.f);
  glVertex3f(100.f, -100.f, -520.f);

  /* ceiling */
  glNormal3f(0.f, -1.f, 0.f);
  glVertex3f(-100.f, 100.f, -320.f);
  glVertex3f(-100.f, 100.f, -520.f);
  glVertex3f(100.f, 100.f, -520.f);
  glVertex3f(100.f, 100.f, -320.f);

  /* back wall */
  glNormal3f(0.f, 0.f, 1.f);
  glVertex3f(-100.f, -100.f, -520.f);
  glVertex3f(100.f, -100.f, -520.f);
  glVertex3f(100.f, 100.f, -520.f);
  glVertex3f(-100.f, 100.f, -520.f);
  glEnd();

  glPushMatrix();
  glTranslatef(-80.f, -80.f, -420.f);
  glCallList(SPHERE);
  glPopMatrix();

  glPushMatrix();
  glTranslatef(-20.f, -100.f, -500.f);
  glCallList(CONE);
  glPopMatrix();

  if (stencil) {
    glEnable(GL_STENCIL_TEST);
    glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
    glStencilFunc(GL_ALWAYS, 1, 1);
    glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
    glPixelTransferf(GL_DEPTH_BIAS, depthbias);

    glDrawPixels(wid, ht, GL_DEPTH_COMPONENT, GL_FLOAT, depth);

    glPixelTransferf(GL_DEPTH_BIAS, 0.f);
    glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
    glStencilFunc(GL_EQUAL, 1, 1);
    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
    glDisable(GL_DEPTH_TEST);

    glDrawPixels(wid, ht, GL_RGB, GL_FLOAT, color);

    glEnable(GL_DEPTH_TEST);
    glDisable(GL_STENCIL_TEST);
  } else
    glDrawPixels(wid, ht, GL_RGB, GL_FLOAT, color);

  glutSwapBuffers();
}

const int TEXDIM = 256;

/* Parse arguments, and set up interface between OpenGL and window system */
int
main(int argc, char *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 *obj;

  glutInit(&argc, argv);
  glutInitWindowSize(WINDIM, WINDIM);

  glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL | GLUT_DOUBLE);
  (void) glutCreateWindow("compositing images with depth");
  glutDisplayFunc(redraw);
  glutKeyboardFunc(key);
  glutMouseFunc(mouse);
  glutMotionFunc(motion);
  glutReshapeFunc(reshape);

  /* draw a perspective scene */
  glMatrixMode(GL_PROJECTION);
  glFrustum(-FRUSTDIM, FRUSTDIM, -FRUSTDIM, FRUSTDIM, FRUSTNEAR, FRUSTFAR);
  glMatrixMode(GL_MODELVIEW);

  /* turn on features */
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);

  /* place light 0 in the right place */
  glLightfv(GL_LIGHT0, GL_POSITION, lightpos);

  /* remove back faces to speed things up */
  glCullFace(GL_BACK);

  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

  glNewList(SPHERE, GL_COMPILE);
  /* make display lists for sphere and cone; for efficiency */
  obj = gluNewQuadric();
  glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, sphere_mat);
  gluSphere(obj, 20.f, 20, 20);
  glEndList();

  glNewList(CONE, GL_COMPILE);
  glRotatef(-90.f, 1.f, 0.f, 0.f);
  glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, cone_mat);
  gluQuadricOrientation(obj, GLU_INSIDE);
  gluDisk(obj, 0., 20., 20, 1);
  gluQuadricOrientation(obj, GLU_OUTSIDE);
  gluCylinder(obj, 20., 0., 60., 20, 20);
  glEndList();

  gluDeleteQuadric(obj);

  /* load pattern for current 2d texture */
  tex = make_texture(TEXDIM, TEXDIM);
  glTexImage2D(GL_TEXTURE_2D, 0, 1, TEXDIM, TEXDIM, 0, GL_RED, GL_FLOAT, tex);
  free(tex);

  /* storage for saved image */
  color = 0;
  depth = 0;

  glReadBuffer(GL_FRONT);  /* so glReadPixel() always get the right image */
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  glPixelStorei(GL_PACK_ALIGNMENT, 1);

  glutInitDisplayMode(GLUT_SINGLE | GLUT_INDEX);
  if (glutLayerGet(GLUT_OVERLAY_POSSIBLE)) {
    glutEstablishOverlay();
    glutHideOverlay();
    transparent = glutLayerGet(GLUT_TRANSPARENT_INDEX);
    glClearIndex(transparent);
    red = (transparent + 1) % glutGet(GLUT_WINDOW_COLORMAP_SIZE);
    glutSetColor(red, 1.0, 0.0, 0.0);  /* Red. */
    glutOverlayDisplayFunc(overlay);
    overlaySupport = 1;
  } else {
    printf("Running without overlay rubber banding support.\n");
  }
  glutMainLoop();
  return 0;             /* ANSI C requires main to return int. */
}
