diff options
Diffstat (limited to 'src/box3d.cpp')
| -rw-r--r-- | src/box3d.cpp | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/src/box3d.cpp b/src/box3d.cpp index e445ba3d0..7f04efde6 100644 --- a/src/box3d.cpp +++ b/src/box3d.cpp @@ -103,6 +103,11 @@ sp_3dbox_build(SPObject *object, SPDocument *document, Inkscape::XML::Node *repr box->my_counter = counter++; + /* we initialize the z-orders to zero so that they are updated during dragging */ + for (int i = 0; i < 6; ++i) { + box->z_orders[i] = 0; + } + box->front_bits = 0x0; if (repr->attribute ("inkscape:perspective") == NULL) { @@ -368,6 +373,110 @@ void sp_3dbox_recompute_corners (SP3DBox *box, NR::Point const A, NR::Point cons sp_3dbox_move_corner_in_Z_direction (box, 5, C); } +inline static double +normalized_angle (double angle) { + if (angle < -M_PI) { + return angle + 2*M_PI; + } else if (angle > M_PI) { + return angle - 2*M_PI; + } + return angle; +} + +static gdouble +sp_3dbox_corner_angle_to_VP (SP3DBox *box, Box3D::Axis axis, guint extreme_corner) +{ + Box3D::VanishingPoint *vp = Box3D::get_persp_of_box (box)->get_vanishing_point (axis); + NR::Point dir; + + if (vp->is_finite()) { + dir = NR::unit_vector (vp->get_pos() - box->corners[extreme_corner]); + } else { + dir = NR::unit_vector (vp->v_dir); + } + + return atan2 (dir[NR::Y], dir[NR::X]); +} + + +bool sp_3dbox_recompute_z_orders (SP3DBox *box) +{ + guint new_z_orders[6]; + + Box3D::Perspective3D *persp = Box3D::get_persp_of_box (box); + + // TODO: Determine the front corner depending on the distance from VPs and/or the user presets + guint front_corner = 1; + + gdouble dir_1x = sp_3dbox_corner_angle_to_VP (box, Box3D::X, front_corner); + gdouble dir_3x = sp_3dbox_corner_angle_to_VP (box, Box3D::X, front_corner ^ Box3D::Y); + + gdouble dir_1y = sp_3dbox_corner_angle_to_VP (box, Box3D::Y, front_corner); + gdouble dir_0y = sp_3dbox_corner_angle_to_VP (box, Box3D::Y, front_corner ^ Box3D::X); + + gdouble dir_1z = sp_3dbox_corner_angle_to_VP (box, Box3D::Z, front_corner); + gdouble dir_3z = sp_3dbox_corner_angle_to_VP (box, Box3D::Z, front_corner ^ Box3D::Y); + + // Still not perfect, but only fails in some rather degenerate cases. + // I suspect that there is a more elegant model, though. :) + new_z_orders[0] = Box3D::face_to_int (Box3D::XY ^ Box3D::FRONT); + if (normalized_angle (dir_1y - dir_1z) > 0) { + new_z_orders[1] = Box3D::face_to_int (Box3D::YZ ^ Box3D::REAR); + if (normalized_angle (dir_1x - dir_1z) > 0) { + new_z_orders[2] = Box3D::face_to_int (Box3D::XZ ^ Box3D::REAR); + } else { + new_z_orders[2] = Box3D::face_to_int (Box3D::XZ ^ Box3D::FRONT); + } + } else { + if (normalized_angle (dir_3x - dir_3z) > 0) { + new_z_orders[1] = Box3D::face_to_int (Box3D::XZ ^ Box3D::REAR); + new_z_orders[2] = Box3D::face_to_int (Box3D::YZ ^ Box3D::FRONT); + } else { + if (normalized_angle (dir_1x - dir_1z) > 0) { + new_z_orders[1] = Box3D::face_to_int (Box3D::YZ ^ Box3D::FRONT); + new_z_orders[2] = Box3D::face_to_int (Box3D::XZ ^ Box3D::FRONT); + } else { + new_z_orders[1] = Box3D::face_to_int (Box3D::XZ ^ Box3D::FRONT); + new_z_orders[2] = Box3D::face_to_int (Box3D::YZ ^ Box3D::FRONT); + } + } + } + + new_z_orders[3] = Box3D::opposite_face (new_z_orders[2]); + new_z_orders[4] = Box3D::opposite_face (new_z_orders[1]); + new_z_orders[5] = Box3D::opposite_face (new_z_orders[0]); + + /* We only need to look for changes among the topmost three faces because the order + of the other ones is just inverted. */ + // Currently we can even skip the first test since the front face is always in the XY plane. + if (// (box->z_orders[0] != new_z_orders[0]) || + (box->z_orders[1] != new_z_orders[1]) || + (box->z_orders[2] != new_z_orders[2])) + { + for (int i = 0; i < 6; ++i) { + box->z_orders[i] = new_z_orders[i]; + } + return true; + } + + return false; +} + +void sp_3dbox_set_z_orders (SP3DBox *box) +{ + GSList *items = sp_item_group_item_list(SP_GROUP(box)); + + // For efficiency reasons, we only set the new z-orders if something really changed + if (sp_3dbox_recompute_z_orders (box)) { + box->faces[box->z_orders[0]]->lower_to_bottom (); + box->faces[box->z_orders[1]]->lower_to_bottom (); + box->faces[box->z_orders[2]]->lower_to_bottom (); + box->faces[box->z_orders[3]]->lower_to_bottom (); + box->faces[box->z_orders[4]]->lower_to_bottom (); + box->faces[box->z_orders[5]]->lower_to_bottom (); + } +} + void sp_3dbox_update_curves (SP3DBox *box) { for (int i = 0; i < 6; ++i) { |