Exemplo n.º 1
0
/**
 * gimp_vector_3d_to_2d:
 * @sx: the abscissa of the upper-left screen rectangle.
 * @sy: the ordinate of the upper-left screen rectangle.
 * @w: the width of the screen rectangle.
 * @h: the height of the screen rectangle.
 * @x: the abscissa of the point in the screen rectangle to map (return value).
 * @y: the ordinate of the point in the screen rectangle to map (return value).
 * @vp: position of the observer.
 * @p: the 3D point to project to the plane.
 *
 * Convert the given 3D point to 2D (project it onto the viewing
 * plane, (sx, sy, 0) - (sx + w, sy + h, 0). The input is assumed to
 * be in the unit square (0, 0, z) - (1, 1, z). The viewpoint of the
 * observer is passed in vp.
 *
 * This is basically the opposite of gimp_vector_2d_to_3d().
 **/
void
gimp_vector_3d_to_2d (gint               sx,
                      gint               sy,
                      gint               w,
                      gint               h,
                      gdouble           *x,
                      gdouble           *y,
                      const GimpVector3 *vp,
                      const GimpVector3 *p)
{
  gdouble     t;
  GimpVector3 dir;

  gimp_vector3_sub (&dir, p, vp);
  gimp_vector3_normalize (&dir);

  if (dir.z != 0.0)
    {
      t = (-1.0 * vp->z) / dir.z;
      *x = (gdouble) sx + ((vp->x + t * dir.x) * (gdouble) w);
      *y = (gdouble) sy + ((vp->y + t * dir.y) * (gdouble) h);
    }
  else
    {
      *x = (gdouble) sx + (p->x * (gdouble) w);
      *y = (gdouble) sy + (p->y * (gdouble) h);
    }
}
Exemplo n.º 2
0
void
compute_bounding_box (void)
{
  GimpVector3  p1, p2;
  gdouble      t;
  GimpVector3  dir;

  p1 = mapvals.position;
  p1.x -= (mapvals.radius + 0.01);
  p1.y -= (mapvals.radius + 0.01);

  p2 = mapvals.position;
  p2.x += (mapvals.radius + 0.01);
  p2.y += (mapvals.radius + 0.01);

  gimp_vector3_sub (&dir, &p1, &mapvals.viewpoint);
  gimp_vector3_normalize (&dir);

  if (dir.z != 0.0)
    {
      t = (-1.0 * mapvals.viewpoint.z) / dir.z;
      p1.x = (mapvals.viewpoint.x + t * dir.x);
      p1.y = (mapvals.viewpoint.y + t * dir.y);
    }

  gimp_vector3_sub (&dir, &p2, &mapvals.viewpoint);
  gimp_vector3_normalize (&dir);

  if (dir.z != 0.0)
    {
      t = (-1.0 * mapvals.viewpoint.z) / dir.z;
      p2.x = (mapvals.viewpoint.x + t * dir.x);
      p2.y = (mapvals.viewpoint.y + t * dir.y);
    }

  bx1 = p1.x;
  by1 = p1.y;
  bx2 = p2.x;
  by2 = p2.y;
}
Exemplo n.º 3
0
GimpRGB
get_ray_color_plane (GimpVector3 *pos)
{
  GimpRGB color = background;

  static gint         inside = FALSE;
  static GimpVector3  ray, spos;
  static gdouble      vx, vy;

  /* Construct a line from our VP to the point */
  /* ========================================= */

  gimp_vector3_sub (&ray, pos, &mapvals.viewpoint);
  gimp_vector3_normalize (&ray);

  /* Check for intersection. This is a quasi ray-tracer. */
  /* =================================================== */

  if (plane_intersect (&ray, &mapvals.viewpoint, &spos, &vx, &vy) == TRUE)
    {
      color = get_image_color (vx, vy, &inside);

      if (color.a != 0.0 && inside == TRUE &&
	  mapvals.lightsource.type != NO_LIGHT)
        {
          /* Compute shading at this point */
          /* ============================= */

          color = phong_shade (&spos,
			       &mapvals.viewpoint,
			       &mapvals.normal,
			       &mapvals.lightsource.position,
			       &color,
			       &mapvals.lightsource.color,
			       mapvals.lightsource.type);

          gimp_rgb_clamp (&color);
        }
    }

  if (mapvals.transparent_background == FALSE && color.a < 1.0)
    {
      gimp_rgb_composite (&color, &background,
			  GIMP_RGB_COMPOSITE_BEHIND);
    }

  return color;
}
Exemplo n.º 4
0
static GimpVector3
compute_reflected_ray (GimpVector3 *normal,
                       GimpVector3 *view)
{
  GimpVector3 ref;
  gdouble     nl;

  nl = 2.0 * gimp_vector3_inner_product (normal, view);

  ref = *normal;

  gimp_vector3_mul (&ref, nl);
  gimp_vector3_sub (&ref, &ref, view);

  return ref;
}
Exemplo n.º 5
0
static gint
sphere_intersect (GimpVector3 *dir,
		  GimpVector3 *viewp,
		  GimpVector3 *spos1,
		  GimpVector3 *spos2)
{
  static gdouble      alpha, beta, tau, s1, s2, tmp;
  static GimpVector3  t;

  gimp_vector3_sub (&t, &mapvals.position, viewp);

  alpha = gimp_vector3_inner_product (dir, &t);
  beta  = gimp_vector3_inner_product (&t, &t);

  tau = alpha * alpha - beta + mapvals.radius * mapvals.radius;

  if (tau >= 0.0)
    {
      tau = sqrt (tau);
      s1 = alpha + tau;
      s2 = alpha - tau;

      if (s2 < s1)
        {
          tmp = s1;
          s1 = s2;
          s2 = tmp;
        }

      spos1->x = viewp->x + s1 * dir->x;
      spos1->y = viewp->y + s1 * dir->y;
      spos1->z = viewp->z + s1 * dir->z;
      spos2->x = viewp->x + s2 * dir->x;
      spos2->y = viewp->y + s2 * dir->y;
      spos2->z = viewp->z + s2 * dir->z;

      return TRUE;
    }

  return FALSE;
}
Exemplo n.º 6
0
GimpRGB
get_ray_color_box (GimpVector3 *pos)
{
  GimpVector3        lvp, ldir, vp, p, dir, ns, nn;
  GimpRGB             color, color2;
  gfloat             m[16];
  gint               i;
  FaceIntersectInfo  face_intersect[2];

  color = background;
  vp = mapvals.viewpoint;
  p = *pos;

  /* Translate viewpoint so that the box has its origin */
  /* at its lower left corner.                          */
  /* ================================================== */

  vp.x = vp.x - mapvals.position.x;
  vp.y = vp.y - mapvals.position.y;
  vp.z = vp.z - mapvals.position.z;

  p.x = p.x - mapvals.position.x;
  p.y = p.y - mapvals.position.y;
  p.z = p.z - mapvals.position.z;

  /* Compute direction */
  /* ================= */

  gimp_vector3_sub (&dir, &p, &vp);
  gimp_vector3_normalize (&dir);

  /* Compute inverse of rotation matrix and apply it to   */
  /* the viewpoint and direction. This transforms the     */
  /* observer into the local coordinate system of the box */
  /* ==================================================== */

  memcpy (m, rotmat, sizeof (gfloat) * 16);

  transpose_mat (m);

  vecmulmat (&lvp, &vp, m);
  vecmulmat (&ldir, &dir, m);

  /* Ok. Now the observer is in the space where the box is located */
  /* with its lower left corner at the origin and its axis aligned */
  /* to the cartesian basis. Check if the transformed ray hits it. */
  /* ============================================================= */

  face_intersect[0].t = 1000000.0;
  face_intersect[1].t = 1000000.0;

  if (intersect_box (mapvals.scale, lvp, ldir, face_intersect) == TRUE)
    {
      /* We've hit the box. Transform the hit points and */
      /* normals back into the world coordinate system   */
      /* =============================================== */

      for (i = 0; i < 2; i++)
        {
          vecmulmat (&ns, &face_intersect[i].s, rotmat);
          vecmulmat (&nn, &face_intersect[i].n, rotmat);

          ns.x = ns.x + mapvals.position.x;
          ns.y = ns.y + mapvals.position.y;
          ns.z = ns.z + mapvals.position.z;

          face_intersect[i].s = ns;
          face_intersect[i].n = nn;
        }

      color = get_box_image_color (face_intersect[0].face,
				   face_intersect[0].u,
				   face_intersect[0].v);

      /* Check for total transparency... */
      /* =============================== */

      if (color.a < 1.0)
        {
          /* Hey, we can see  through here!      */
          /* Lets see what's on the other side.. */
          /* =================================== */

          color = phong_shade (&face_intersect[0].s,
			       &mapvals.viewpoint,
			       &face_intersect[0].n,
			       &mapvals.lightsource.position,
			       &color,
			       &mapvals.lightsource.color,
			       mapvals.lightsource.type);

          gimp_rgb_clamp (&color);

          color2 = get_box_image_color (face_intersect[1].face,
					face_intersect[1].u,
					face_intersect[1].v);

          /* Make the normal point inwards */
          /* ============================= */

          gimp_vector3_mul (&face_intersect[1].n, -1.0);

          color2 = phong_shade (&face_intersect[1].s,
				&mapvals.viewpoint,
				&face_intersect[1].n,
				&mapvals.lightsource.position,
				&color2,
				&mapvals.lightsource.color,
				mapvals.lightsource.type);

          gimp_rgb_clamp (&color2);

          if (mapvals.transparent_background == FALSE && color2.a < 1.0)
            {
	      gimp_rgb_composite (&color2, &background,
				  GIMP_RGB_COMPOSITE_BEHIND);
	    }

          /* Compute a mix of the first and second colors */
          /* ============================================ */

	  gimp_rgb_composite (&color, &color2, GIMP_RGB_COMPOSITE_NORMAL);
          gimp_rgb_clamp (&color);
        }
      else if (color.a != 0.0 && mapvals.lightsource.type != NO_LIGHT)
        {
	  color = phong_shade (&face_intersect[0].s,
			       &mapvals.viewpoint,
			       &face_intersect[0].n,
			       &mapvals.lightsource.position,
			       &color,
			       &mapvals.lightsource.color,
			       mapvals.lightsource.type);

	  gimp_rgb_clamp (&color);
        }
    }
  else
    {
      if (mapvals.transparent_background == TRUE)
	gimp_rgb_set_alpha (&color, 0.0);
    }

  return color;
}
Exemplo n.º 7
0
GimpRGB
get_ray_color_sphere (GimpVector3 *pos)
{
  GimpRGB color = background;

  static GimpRGB      color2;
  static gint         inside = FALSE;
  static GimpVector3  normal, ray, spos1, spos2;
  static gdouble      vx, vy;

  /* Check if ray is within the bounding box */
  /* ======================================= */

  if (pos->x<bx1 || pos->x>bx2 || pos->y<by1 || pos->y>by2)
    return color;

  /* Construct a line from our VP to the point */
  /* ========================================= */

  gimp_vector3_sub (&ray, pos, &mapvals.viewpoint);
  gimp_vector3_normalize (&ray);

  /* Check for intersection. This is a quasi ray-tracer. */
  /* =================================================== */

  if (sphere_intersect (&ray, &mapvals.viewpoint, &spos1, &spos2) == TRUE)
    {
      /* Compute spherical to rectangular mapping */
      /* ======================================== */

      gimp_vector3_sub (&normal, &spos1, &mapvals.position);
      gimp_vector3_normalize (&normal);
      sphere_to_image (&normal, &vx, &vy);
      color = get_image_color (vx, vy, &inside);

      /* Check for total transparency... */
      /* =============================== */

      if (color.a < 1.0)
        {
          /* Hey, we can see  through here!      */
          /* Lets see what's on the other side.. */
          /* =================================== */

          color = phong_shade (&spos1,
			       &mapvals.viewpoint,
			       &normal,
			       &mapvals.lightsource.position,
			       &color,
			       &mapvals.lightsource.color,
			       mapvals.lightsource.type);

          gimp_rgb_clamp (&color);

          gimp_vector3_sub (&normal, &spos2, &mapvals.position);
          gimp_vector3_normalize (&normal);
          sphere_to_image (&normal, &vx, &vy);
          color2 = get_image_color (vx, vy, &inside);

          /* Make the normal point inwards */
          /* ============================= */

          gimp_vector3_mul (&normal, -1.0);

          color2 = phong_shade (&spos2,
				&mapvals.viewpoint,
				&normal,
				&mapvals.lightsource.position,
				&color2,
				&mapvals.lightsource.color,
				mapvals.lightsource.type);

          gimp_rgb_clamp (&color2);

          /* Compute a mix of the first and second colors */
          /* ============================================ */

	  gimp_rgb_composite (&color, &color2, GIMP_RGB_COMPOSITE_NORMAL);
          gimp_rgb_clamp (&color);
        }
      else if (color.a != 0.0 &&
	       inside == TRUE &&
	       mapvals.lightsource.type != NO_LIGHT)
        {
          /* Compute shading at this point */
          /* ============================= */

          color = phong_shade (&spos1,
			       &mapvals.viewpoint,
			       &normal,
			       &mapvals.lightsource.position,
			       &color,
			       &mapvals.lightsource.color,
			       mapvals.lightsource.type);

          gimp_rgb_clamp (&color);
        }
    }

  if (mapvals.transparent_background == FALSE && color.a < 1.0)
    {
      gimp_rgb_composite (&color, &background,
			  GIMP_RGB_COMPOSITE_BEHIND);
    }

  return color;
}
Exemplo n.º 8
0
static GimpRGB
phong_shade (GimpVector3 *pos,
	     GimpVector3 *viewpoint,
	     GimpVector3 *normal,
	     GimpVector3 *light,
	     GimpRGB      *diff_col,
	     GimpRGB      *spec_col,
	     gint         type)
{
  GimpRGB       ambientcolor, diffusecolor, specularcolor;
  gdouble      NL, RV, dist;
  GimpVector3  L, NN, V, N;

  /* Compute ambient intensity */
  /* ========================= */

  N = *normal;
  ambientcolor = *diff_col;
  gimp_rgb_multiply (&ambientcolor, mapvals.material.ambient_int);

  /* Compute (N*L) term of Phong's equation */
  /* ====================================== */

  if (type == POINT_LIGHT)
    gimp_vector3_sub (&L, light, pos);
  else
    L = *light;

  dist = gimp_vector3_length (&L);

  if (dist != 0.0)
    gimp_vector3_mul (&L, 1.0 / dist);

  NL = 2.0 * gimp_vector3_inner_product (&N, &L);

  if (NL >= 0.0)
    {
      /* Compute (R*V)^alpha term of Phong's equation */
      /* ============================================ */

      gimp_vector3_sub (&V, viewpoint, pos);
      gimp_vector3_normalize (&V);

      gimp_vector3_mul (&N, NL);
      gimp_vector3_sub (&NN, &N, &L);
      RV = gimp_vector3_inner_product (&NN, &V);
      RV = pow (RV, mapvals.material.highlight);

      /* Compute diffuse and specular intensity contribution */
      /* =================================================== */

      diffusecolor = *diff_col;
      gimp_rgb_multiply (&diffusecolor, mapvals.material.diffuse_ref);
      gimp_rgb_multiply (&diffusecolor, NL);

      specularcolor = *spec_col;
      gimp_rgb_multiply (&specularcolor, mapvals.material.specular_ref);
      gimp_rgb_multiply (&specularcolor, RV);

      gimp_rgb_add (&diffusecolor, &specularcolor);
      gimp_rgb_multiply (&diffusecolor, mapvals.material.diffuse_int);
      gimp_rgb_clamp (&diffusecolor);

      gimp_rgb_add (&ambientcolor, &diffusecolor);
    }

  return ambientcolor;
}
Exemplo n.º 9
0
static void
draw_wireframe_plane (gint startx,
		      gint starty,
		      gint pw,
		      gint ph)
{
  GimpVector3 v1, v2, a, b, c, d, dir1, dir2;
  gint        cnt, n = 0;
  gdouble     x1, y1, x2, y2, cx1, cy1, cx2, cy2, fac;

  /* Find rotated box corners */
  /* ======================== */

  gimp_vector3_set (&v1, 0.5, 0.0, 0.0);
  gimp_vector3_set (&v2, 0.0, 0.5, 0.0);

  gimp_vector3_rotate (&v1,
		       gimp_deg_to_rad (mapvals.alpha),
		       gimp_deg_to_rad (mapvals.beta),
		       gimp_deg_to_rad (mapvals.gamma));

  gimp_vector3_rotate (&v2,
		       gimp_deg_to_rad (mapvals.alpha),
		       gimp_deg_to_rad (mapvals.beta),
		       gimp_deg_to_rad (mapvals.gamma));

  dir1 = v1; gimp_vector3_normalize (&dir1);
  dir2 = v2; gimp_vector3_normalize (&dir2);

  fac = 1.0 / (gdouble) WIRESIZE;

  gimp_vector3_mul (&dir1, fac);
  gimp_vector3_mul (&dir2, fac);

  gimp_vector3_add (&a, &mapvals.position, &v1);
  gimp_vector3_sub (&b, &a, &v2);
  gimp_vector3_add (&a, &a, &v2);
  gimp_vector3_sub (&d, &mapvals.position, &v1);
  gimp_vector3_sub (&d, &d, &v2);

  c = b;

  cx1 = (gdouble) startx;
  cy1 = (gdouble) starty;
  cx2 = cx1 + (gdouble) pw;
  cy2 = cy1 + (gdouble) ph;

  for (cnt = 0; cnt <= WIRESIZE; cnt++)
    {
      gimp_vector_3d_to_2d (startx, starty, pw, ph,
			    &x1, &y1, &mapvals.viewpoint, &a);
      gimp_vector_3d_to_2d (startx, starty, pw, ph,
			    &x2, &y2, &mapvals.viewpoint, &b);

      if (clip_line (&x1, &y1, &x2, &y2, cx1, cy1, cx2, cy2) == TRUE)
        {
          linetab[n].x1 = RINT (x1);
          linetab[n].y1 = RINT (y1);
          linetab[n].x2 = RINT (x2);
          linetab[n].y2 = RINT (y2);
          linetab[n].linewidth = 1;
          linetab[n].linestyle = GDK_LINE_SOLID;
          gdk_gc_set_line_attributes (gc,
				      linetab[n].linewidth,
				      linetab[n].linestyle,
				      GDK_CAP_NOT_LAST,
				      GDK_JOIN_MITER);
          gdk_draw_line (previewarea->window, gc,
			 linetab[n].x1, linetab[n].y1,
			 linetab[n].x2, linetab[n].y2);
          n++;
        }

      gimp_vector_3d_to_2d (startx, starty, pw, ph,
			    &x1, &y1, &mapvals.viewpoint, &c);
      gimp_vector_3d_to_2d (startx, starty, pw, ph,
			    &x2, &y2, &mapvals.viewpoint, &d);

      if (clip_line (&x1, &y1, &x2, &y2, cx1, cy1, cx2, cy2) == TRUE)
        {
          linetab[n].x1 = RINT (x1);
          linetab[n].y1 = RINT (y1);
          linetab[n].x2 = RINT (x2);
          linetab[n].y2 = RINT (y2);
          linetab[n].linewidth = 1;
          linetab[n].linestyle = GDK_LINE_SOLID;
          gdk_gc_set_line_attributes (gc,
				      linetab[n].linewidth,
				      linetab[n].linestyle,
				      GDK_CAP_NOT_LAST,
				      GDK_JOIN_MITER);
          gdk_draw_line (previewarea->window, gc,
			 linetab[n].x1, linetab[n].y1,
			 linetab[n].x2, linetab[n].y2);
          n++;
        }

      gimp_vector3_sub (&a, &a, &dir1);
      gimp_vector3_sub (&b, &b, &dir1);
      gimp_vector3_add (&c, &c, &dir2);
      gimp_vector3_add (&d, &d, &dir2);
    }

  /* Mark end of lines */
  /* ================= */

  linetab[n].x1 = -1;
}
Exemplo n.º 10
0
GimpRGB
get_ray_color_no_bilinear_ref (GimpVector3 *position)
{
  GimpRGB      color_sum;
  GimpRGB      color_int;
  GimpRGB      light_color;
  GimpRGB      color, env_color;
  gint         x;
  gdouble      xf, yf;
  GimpVector3  normal, *p, v, r;
  gint         k;
  gdouble      tmpval;

  pos_to_float (position->x, position->y, &xf, &yf);

  x = RINT (xf);

  if (mapvals.bump_mapped == FALSE || mapvals.bumpmap_id == -1)
    normal = mapvals.planenormal;
  else
    normal = vertex_normals[1][(gint) RINT (xf)];
  gimp_vector3_normalize (&normal);

  if (mapvals.transparent_background && heights[1][x] == 0)
    {
      gimp_rgb_set_alpha (&color_sum, 0.0);
    }
  else
    {
      color = peek (RINT (xf), RINT (yf));
      color_sum = color;
      gimp_rgb_multiply (&color_sum, mapvals.material.ambient_int);

      for (k = 0; k < NUM_LIGHTS; k++)
        {
          p = &mapvals.lightsource[k].direction;

          if (!mapvals.lightsource[k].active
              || mapvals.lightsource[k].type == NO_LIGHT)
            continue;
          else if (mapvals.lightsource[k].type == POINT_LIGHT)
            p = &mapvals.lightsource[k].position;

          color_int = mapvals.lightsource[k].color;
          gimp_rgb_multiply (&color_int, mapvals.lightsource[k].intensity);

              light_color = phong_shade (position,
                                         &mapvals.viewpoint,
                                         &normal,
                                         p,
                                         &color,
                                         &color_int,
                                         mapvals.lightsource[0].type);
        }

      gimp_vector3_sub (&v, &mapvals.viewpoint, position);
      gimp_vector3_normalize (&v);

      r = compute_reflected_ray (&normal, &v);

      /* Get color in the direction of r */
      /* =============================== */

      sphere_to_image (&r, &xf, &yf);
      env_color = peek_env_map (RINT (env_width * xf),
                                RINT (env_height * yf));

      tmpval = mapvals.material.diffuse_int;
      mapvals.material.diffuse_int = 0.;

      light_color = phong_shade (position,
                                 &mapvals.viewpoint,
                                 &normal,
                                 &r,
                                 &color,
                                 &env_color,
                                 DIRECTIONAL_LIGHT);

      mapvals.material.diffuse_int = tmpval;

      gimp_rgb_add (&color_sum, &light_color);
    }

 gimp_rgb_clamp (&color_sum);
 return color_sum;
}
Exemplo n.º 11
0
static GimpRGB
phong_shade (GimpVector3 *position,
             GimpVector3 *viewpoint,
             GimpVector3 *normal,
             GimpVector3 *lightposition,
             GimpRGB      *diff_col,
             GimpRGB      *light_col,
             LightType    light_type)
{
  GimpRGB       diffuse_color, specular_color;
  gdouble      nl, rv, dist;
  GimpVector3  l, v, n, lnormal, h;

  /* Compute ambient intensity */
  /* ========================= */

  n = *normal;

  /* Compute (N*L) term of Phong's equation */
  /* ====================================== */

  if (light_type == POINT_LIGHT)
    gimp_vector3_sub (&l, lightposition, position);
  else
    {
      l = *lightposition;
      gimp_vector3_normalize (&l);
    }

  dist = gimp_vector3_length (&l);

  if (dist != 0.0)
    gimp_vector3_mul (&l, 1.0 / dist);

  nl = MAX (0., 2.0 * gimp_vector3_inner_product (&n, &l));

  lnormal = l;
  gimp_vector3_normalize (&lnormal);

  if (nl >= 0.0)
    {
      /* Compute (R*V)^alpha term of Phong's equation */
      /* ============================================ */

      gimp_vector3_sub (&v, viewpoint, position);
      gimp_vector3_normalize (&v);

      gimp_vector3_add (&h, &lnormal, &v);
      gimp_vector3_normalize (&h);

      rv = MAX (0.01, gimp_vector3_inner_product (&n, &h));
      rv = pow (rv, mapvals.material.highlight);
      rv *= nl;

      /* Compute diffuse and specular intensity contribution */
      /* =================================================== */

      diffuse_color = *light_col;
      gimp_rgb_multiply (&diffuse_color, mapvals.material.diffuse_int);
      diffuse_color.r *= diff_col->r;
      diffuse_color.g *= diff_col->g;
      diffuse_color.b *= diff_col->b;
      gimp_rgb_multiply (&diffuse_color, nl);

      specular_color = *light_col;
      if (mapvals.material.metallic)  /* for metals, specular color = diffuse color */
        {
          specular_color.r *= diff_col->r;
          specular_color.g *= diff_col->g;
          specular_color.b *= diff_col->b;
        }
      gimp_rgb_multiply (&specular_color, mapvals.material.specular_ref);
      gimp_rgb_multiply (&specular_color, rv);

      gimp_rgb_add (&diffuse_color, &specular_color);
      gimp_rgb_clamp (&diffuse_color);
    }

  gimp_rgb_clamp (&diffuse_color);

  return diffuse_color;
}