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;
}
static void
draw_wireframe_cylinder (gint startx,
gint starty,
gint pw,
gint ph)
{
GimpVector3 p[2*8], a, axis, scale;
gint n = 0, i;
gdouble cx1, cy1, cx2, cy2;
gfloat m[16], l, angle;
/* Compute wireframe points */
/* ======================== */
init_compute ();
scale = mapvals.scale;
gimp_vector3_mul (&scale, 0.5);
l = mapvals.cylinder_length / 2.0;
angle = 0;
gimp_vector3_set (&axis, 0.0, 1.0, 0.0);
for (i = 0; i < 8; i++)
{
rotatemat (angle, &axis, m);
gimp_vector3_set (&a, mapvals.cylinder_radius, 0.0, 0.0);
vecmulmat (&p[i], &a, m);
p[i+8] = p[i];
p[i].y += l;
p[i+8].y -= l;
angle += 360.0 / 8.0;
}
/* Rotate and translate points */
/* =========================== */
for (i = 0; i < 16; i++)
{
vecmulmat (&a, &p[i], rotmat);
gimp_vector3_add (&p[i], &a, &mapvals.position);
}
/* Draw the box */
/* ============ */
cx1 = (gdouble) startx;
cy1 = (gdouble) starty;
cx2 = cx1 + (gdouble) pw;
cy2 = cy1 + (gdouble) ph;
for (i = 0; i < 7; i++)
{
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[i],p[i+1]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[i+8],p[i+9]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[i],p[i+8]);
}
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[7],p[0]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[15],p[8]);
/* Mark end of lines */
/* ================= */
linetab[n].x1 = -1;
}
static gboolean
intersect_box (GimpVector3 scale,
GimpVector3 viewp,
GimpVector3 dir,
FaceIntersectInfo *face_intersect)
{
GimpVector3 v, d, tmp, axis[3];
FaceIntersectInfo face_tmp;
gboolean result = FALSE;
gfloat m[16];
gint i = 0;
gimp_vector3_set (&axis[0], 1.0, 0.0, 0.0);
gimp_vector3_set (&axis[1], 0.0, 1.0, 0.0);
gimp_vector3_set (&axis[2], 0.0, 0.0, 1.0);
/* Front side */
/* ========== */
if (intersect_rect (scale.x, scale.y, scale.z / 2.0,
viewp, dir, &face_intersect[i]) == TRUE)
{
face_intersect[i].face = 0;
gimp_vector3_set (&face_intersect[i++].n, 0.0, 0.0, 1.0);
result = TRUE;
}
/* Back side */
/* ========= */
if (intersect_rect (scale.x, scale.y, -scale.z / 2.0,
viewp, dir, &face_intersect[i]) == TRUE)
{
face_intersect[i].face = 1;
face_intersect[i].u = 1.0 - face_intersect[i].u;
gimp_vector3_set (&face_intersect[i++].n, 0.0, 0.0, -1.0);
result = TRUE;
}
/* Check if we've found the two possible intersection points */
/* ========================================================= */
if (i < 2)
{
/* Top: Rotate viewpoint and direction into rectangle's local coordinate system */
/* ============================================================================ */
rotatemat (90, &axis[0], m);
vecmulmat (&v, &viewp, m);
vecmulmat (&d, &dir, m);
if (intersect_rect (scale.x, scale.z, scale.y / 2.0,
v, d, &face_intersect[i]) == TRUE)
{
face_intersect[i].face = 2;
transpose_mat (m);
vecmulmat(&tmp, &face_intersect[i].s, m);
face_intersect[i].s = tmp;
gimp_vector3_set (&face_intersect[i++].n, 0.0, -1.0, 0.0);
result = TRUE;
}
}
/* Check if we've found the two possible intersection points */
/* ========================================================= */
if (i < 2)
{
/* Bottom: Rotate viewpoint and direction into rectangle's local coordinate system */
/* =============================================================================== */
rotatemat (90, &axis[0], m);
vecmulmat (&v, &viewp, m);
vecmulmat (&d, &dir, m);
if (intersect_rect (scale.x, scale.z, -scale.y / 2.0,
v, d, &face_intersect[i]) == TRUE)
{
face_intersect[i].face = 3;
transpose_mat (m);
vecmulmat (&tmp, &face_intersect[i].s, m);
face_intersect[i].s = tmp;
face_intersect[i].v = 1.0 - face_intersect[i].v;
gimp_vector3_set (&face_intersect[i++].n, 0.0, 1.0, 0.0);
result = TRUE;
}
}
/* Check if we've found the two possible intersection points */
/* ========================================================= */
if (i < 2)
{
/* Left side: Rotate viewpoint and direction into rectangle's local coordinate system */
/* ================================================================================== */
rotatemat (90, &axis[1], m);
vecmulmat (&v, &viewp, m);
vecmulmat (&d, &dir, m);
if (intersect_rect (scale.z, scale.y, scale.x / 2.0,
v, d, &face_intersect[i]) == TRUE)
{
face_intersect[i].face = 4;
transpose_mat (m);
vecmulmat (&tmp, &face_intersect[i].s, m);
face_intersect[i].s = tmp;
gimp_vector3_set (&face_intersect[i++].n, 1.0, 0.0, 0.0);
result = TRUE;
}
}
/* Check if we've found the two possible intersection points */
/* ========================================================= */
if (i < 2)
{
/* Right side: Rotate viewpoint and direction into rectangle's local coordinate system */
/* =================================================================================== */
rotatemat (90, &axis[1], m);
vecmulmat (&v, &viewp, m);
vecmulmat (&d, &dir, m);
if (intersect_rect (scale.z, scale.y, -scale.x / 2.0,
v, d, &face_intersect[i]) == TRUE)
{
face_intersect[i].face = 5;
transpose_mat (m);
vecmulmat (&tmp, &face_intersect[i].s, m);
face_intersect[i].u = 1.0 - face_intersect[i].u;
gimp_vector3_set (&face_intersect[i++].n, -1.0, 0.0, 0.0);
result = TRUE;
}
}
/* Sort intersection points */
/* ======================== */
if (face_intersect[0].t > face_intersect[1].t)
{
face_tmp = face_intersect[0];
face_intersect[0] = face_intersect[1];
face_intersect[1] = face_tmp;
}
return result;
}
static void
draw_wireframe_box (gint startx,
gint starty,
gint pw,
gint ph)
{
GimpVector3 p[8], tmp, scale;
gint n = 0, i;
gdouble cx1, cy1, cx2, cy2;
/* Compute wireframe points */
/* ======================== */
init_compute ();
scale = mapvals.scale;
gimp_vector3_mul (&scale, 0.5);
gimp_vector3_set (&p[0], -scale.x, -scale.y, scale.z);
gimp_vector3_set (&p[1], scale.x, -scale.y, scale.z);
gimp_vector3_set (&p[2], scale.x, scale.y, scale.z);
gimp_vector3_set (&p[3], -scale.x, scale.y, scale.z);
gimp_vector3_set (&p[4], -scale.x, -scale.y, -scale.z);
gimp_vector3_set (&p[5], scale.x, -scale.y, -scale.z);
gimp_vector3_set (&p[6], scale.x, scale.y, -scale.z);
gimp_vector3_set (&p[7], -scale.x, scale.y, -scale.z);
/* Rotate and translate points */
/* =========================== */
for (i = 0; i < 8; i++)
{
vecmulmat (&tmp, &p[i], rotmat);
gimp_vector3_add (&p[i], &tmp, &mapvals.position);
}
/* Draw the box */
/* ============ */
cx1 = (gdouble) startx;
cy1 = (gdouble) starty;
cx2 = cx1 + (gdouble) pw;
cy2 = cy1 + (gdouble) ph;
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[0],p[1]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[1],p[2]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[2],p[3]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[3],p[0]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[4],p[5]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[5],p[6]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[6],p[7]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[7],p[4]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[0],p[4]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[1],p[5]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[2],p[6]);
n = draw_line (n, startx,starty,pw,ph, cx1,cy1,cx2,cy2, p[3],p[7]);
/* Mark end of lines */
/* ================= */
linetab[n].x1 = -1;
}
