Refactoring of 3D box internals.

Handle the corners in the box itself and only link to them from the separate faces. This way we can make the code *much* cleaner and more generic.
Provide generic auxiliary functions for the movement of corners in XY-plane and Z-direction.

(bzr r3171)

5 files changed, 132 insertions, 68 deletions

diff --git a/src/box3d-face.cpp b/src/box3d-face.cpp
index e499fe4d0..5eefcb812 100644
--- a/src/box3d-face.cpp
+++ b/src/box3d-face.cpp
@@ -17,10 +17,34 @@
 Box3DFace::Box3DFace(SP3DBox *box3d) : dir1 (Box3D::NONE), dir2 (Box3D::NONE), path (NULL), parent_box3d (box3d)
 {
     for (int i = 0; i < 4; ++i) {
-        this->corners[i] = NR::Point(0, 0);
+        this->corners[i] = new NR::Point(0, 0);
     }
 } 
 
+Box3DFace::Box3DFace(SP3DBox *box3d, NR::Point &A, NR::Point &B, NR::Point &C, NR::Point &D)
+{
+    set_corners (A, B, C, D);
+}
+
+Box3DFace::~Box3DFace()
+{
+    for (int i = 0; i < 4; ++i) {
+        if (this->corners[i]) {
+            delete this->corners[i];
+            this->corners[i] = NULL;
+        }
+    }
+} 
+
+void Box3DFace::set_corners(NR::Point &A, NR::Point &B, NR::Point &C, NR::Point &D)
+{
+    corners[0] = &A;
+    corners[1] = &B;
+    corners[2] = &C;
+    corners[3] = &D;
+}
+
+/***
 void Box3DFace::set_shape(NR::Point const ul, NR::Point const lr,
                      Box3D::Axis const dir1, Box3D::Axis const dir2,
                      unsigned int shift_count, NR::Maybe<NR::Point> pt_align, bool align_along_PL)
@@ -68,6 +92,7 @@ void Box3DFace::set_shape(NR::Point const ul, NR::Point const lr,
     	corners[0] = tmp_pt;
     }
 }
+***/
 
 Box3DFace::Box3DFace(Box3DFace const &box3dface)
 {
@@ -90,8 +115,8 @@ Box3DFace::Box3DFace(Box3DFace const &box3dface)
 void
 Box3DFace::set_face (NR::Point const A, NR::Point const C, Box3D::Axis const axis1, Box3D::Axis const axis2)
 {
-    corners[0] = A;
-    corners[2] = C;
+    *corners[0] = A;
+    *corners[2] = C;
     if (!SP_IS_3DBOX_CONTEXT(inkscape_active_event_context()))
         return;
     SP3DBoxContext *bc = SP_3DBOX_CONTEXT(inkscape_active_event_context());
@@ -100,8 +125,8 @@ Box3DFace::set_face (NR::Point const A, NR::Point const C, Box3D::Axis const axi
     Box3D::PerspectiveLine line2 (C, axis2);
     NR::Maybe<NR::Point> B = line1.intersect(line2);
 
-    Box3D::PerspectiveLine line3 (corners[0], axis2);
-    Box3D::PerspectiveLine line4 (corners[2], axis1);
+    Box3D::PerspectiveLine line3 (*corners[0], axis2);
+    Box3D::PerspectiveLine line4 (*corners[2], axis1);
     NR::Maybe<NR::Point> D = line3.intersect(line4);
 
     // FIXME: How to handle the case if one of the intersections doesn't exist?
@@ -109,8 +134,8 @@ Box3DFace::set_face (NR::Point const A, NR::Point const C, Box3D::Axis const axi
     if (!D) D = NR::Point(0.0, 0.0);    
     if (!B) B = NR::Point(0.0, 0.0);
 
-    corners[1] = *B;
-    corners[3] = *D;
+    *corners[1] = *B;
+    *corners[3] = *D;
 
     this->dir1 = axis1;
     this->dir2 = axis2;
@@ -119,7 +144,7 @@ Box3DFace::set_face (NR::Point const A, NR::Point const C, Box3D::Axis const axi
 
 NR::Point Box3DFace::operator[](unsigned int i)
 {
-    return corners[i % 4];
+    return *corners[i % 4];
 }
 
 /**
@@ -156,10 +181,10 @@ void Box3DFace::set_curve()
         return;
     }
     SPCurve *curve = sp_curve_new();
-    sp_curve_moveto(curve, corners[0][NR::X], height - corners[0][NR::Y]);
-    sp_curve_lineto(curve, corners[1][NR::X], height - corners[1][NR::Y]);
-    sp_curve_lineto(curve, corners[2][NR::X], height - corners[2][NR::Y]);
-    sp_curve_lineto(curve, corners[3][NR::X], height - corners[3][NR::Y]);
+    sp_curve_moveto(curve, (*corners[0])[NR::X], height - (*corners[0])[NR::Y]);
+    sp_curve_lineto(curve, (*corners[1])[NR::X], height - (*corners[1])[NR::Y]);
+    sp_curve_lineto(curve, (*corners[2])[NR::X], height - (*corners[2])[NR::Y]);
+    sp_curve_lineto(curve, (*corners[3])[NR::X], height - (*corners[3])[NR::Y]);
     sp_curve_closepath(curve);
     sp_shape_set_curve(SP_SHAPE(this->path), curve, true);
     sp_curve_unref(curve);
@@ -172,10 +197,10 @@ gchar * Box3DFace::svg_repr_string()
 
     GString *pstring = g_string_new("");
     g_string_sprintf (pstring, "M %f,%f L %f,%f L %f,%f L %f,%f z",
-                               corners[0][NR::X], height - corners[0][NR::Y],
-                               corners[1][NR::X], height - corners[1][NR::Y],
-                               corners[2][NR::X], height - corners[2][NR::Y],
-                               corners[3][NR::X], height - corners[3][NR::Y]);
+                               (*corners[0])[NR::X], height - (*corners[0])[NR::Y],
+                               (*corners[1])[NR::X], height - (*corners[1])[NR::Y],
+                               (*corners[2])[NR::X], height - (*corners[2])[NR::Y],
+                               (*corners[3])[NR::X], height - (*corners[3])[NR::Y]);
     return pstring->str;
 }
 
diff --git a/src/box3d-face.h b/src/box3d-face.h
index e557aebf2..3b96937b6 100644
--- a/src/box3d-face.h
+++ b/src/box3d-face.h
@@ -26,17 +26,23 @@ class SP3DBox;
 class Box3DFace {
 public:
     Box3DFace(SP3DBox *box3d);
+    Box3DFace(SP3DBox *box3d, NR::Point &A, NR::Point &B, NR::Point &C, NR::Point &D);
     //Box3DFace(SP3DBox *box3d, NR::Point const ul, NR::Point const lr,
     //          Box3D::Axis const dir1, Box3D::Axis const dir2,
     //          unsigned int shift_count = 0, NR::Maybe<NR::Point> pt_align = NR::Nothing(), bool align_along_PL = false);
     Box3DFace(Box3DFace const &box3dface);
+    ~Box3DFace();
+
     NR::Point operator[](unsigned int i);
     void draw(SP3DBox *box3d, SPCurve *c);
 
+    /***
     void set_shape(NR::Point const ul, NR::Point const lr,
                    Box3D::Axis const dir1, Box3D::Axis const dir2,
                    unsigned int shift_count = 0, NR::Maybe<NR::Point> pt_align = NR::Nothing(),
                    bool align_along_PL = false);
+    ***/
+    void set_corners (NR::Point &A, NR::Point &B, NR::Point &C, NR::Point &D);
     void set_face (NR::Point const A, NR::Point const C, Box3D::Axis const dir1, Box3D::Axis const dir2);
     
     void hook_path_to_3dbox();
@@ -45,7 +51,7 @@ public:
     gchar * svg_repr_string();
 
 private:
-    NR::Point corners[4];
+    NR::Point *corners[4];
 
     Box3D::Axis dir1;
     Box3D::Axis dir2;
diff --git a/src/box3d.cpp b/src/box3d.cpp
index 290b5111e..258c65879 100644
--- a/src/box3d.cpp
+++ b/src/box3d.cpp
@@ -61,7 +61,7 @@ static void
 sp_3dbox_class_init(SP3DBoxClass *klass)
 {
     SPObjectClass *sp_object_class = (SPObjectClass *) klass;
-    SPItemClass *item_class = (SPItemClass *) klass;
+    // SPItemClass *item_class = (SPItemClass *) klass;
 
     parent_class = (SPGroupClass *) g_type_class_ref(SP_TYPE_GROUP);
 
@@ -76,7 +76,6 @@ sp_3dbox_class_init(SP3DBoxClass *klass)
 static void
 sp_3dbox_init(SP3DBox *box3d)
 {
-    if (box3d == NULL) { g_warning ("box3d is NULL!\n"); }
     box3d->faces[4] = new Box3DFace (box3d);
     //box3d->faces[4]->hook_path_to_3dbox();
     for (int i = 0; i < 6; ++i) {
@@ -163,8 +162,6 @@ static Inkscape::XML::Node *sp_3dbox_write(SPObject *object, Inkscape::XML::Node
 
     box3d->faces[4]->set_path_repr();
     if (bc->extruded) {
-        NR::Point corner1, corner2, corner3, corner4;
-        sp_3dbox_compute_specific_corners (bc, corner1, corner2, corner3, corner4);
         for (int i = 0; i < 6; ++i) {
             if (i == 4) continue;
             box3d->faces[i]->set_path_repr();
@@ -211,61 +208,87 @@ sp_3dbox_set_shape(SP3DBox *box3d)
         return;
     SP3DBoxContext *bc = SP_3DBOX_CONTEXT(inkscape_active_event_context());
 
-    // FIXME: Why must the coordinates be flipped vertically???
-    //SPDocument *doc = SP_OBJECT_DOCUMENT(box3d);
-    //gdouble height = sp_document_height(doc);
-
-    /* Curve-adaption variant: */
-    NR::Point corner1, corner2, corner3, corner4;
-    corner1 = bc->drag_origin;
-
+    /* Only update the curves during dragging; setting the svg representations 
+       is expensive and only done once at the end */
+    sp_3dbox_recompute_corners (box3d, bc->drag_origin, bc->drag_ptB, bc->drag_ptC);
     if (bc->extruded) {
-        sp_3dbox_compute_specific_corners (bc, corner1, corner2, corner3, corner4);
-        for (int i=0; i < 6; ++i) {
-            if (!box3d->faces[i]) {
-                g_warning ("Face no. %d does not exist!\n", i);
-                return;
-            }
-        }
-        box3d->faces[0]->set_face (bc->drag_origin, corner4, Box3D::Z, Box3D::Y);
-        box3d->faces[0]->set_curve();
-        box3d->faces[5]->set_face (corner3, bc->drag_ptC, Box3D::Y, Box3D::X);
-        box3d->faces[5]->set_curve();
-        box3d->faces[3]->set_face (bc->drag_origin, corner2, Box3D::X, Box3D::Z);
-        box3d->faces[3]->set_curve();
-        box3d->faces[2]->set_face (bc->drag_ptB, corner4, Box3D::X, Box3D::Z);
-        box3d->faces[2]->set_curve();
-
-        box3d->faces[1]->set_face (corner1, bc->drag_ptC, Box3D::Z, Box3D::Y);
-        box3d->faces[1]->set_curve();
+        box3d->faces[0]->set_corners (box3d->corners[0], box3d->corners[4], box3d->corners[6], box3d->corners[2]);
+        box3d->faces[1]->set_corners (box3d->corners[1], box3d->corners[5], box3d->corners[7], box3d->corners[3]);
+        box3d->faces[2]->set_corners (box3d->corners[0], box3d->corners[1], box3d->corners[5], box3d->corners[4]);
+        box3d->faces[3]->set_corners (box3d->corners[2], box3d->corners[3], box3d->corners[7], box3d->corners[6]);
+        box3d->faces[5]->set_corners (box3d->corners[4], box3d->corners[5], box3d->corners[7], box3d->corners[6]);
     }
-    box3d->faces[4]->set_face(bc->drag_origin, bc->drag_ptB, Box3D::Y, Box3D::X);
-    box3d->faces[4]->set_curve();
+    box3d->faces[4]->set_corners (box3d->corners[0], box3d->corners[1], box3d->corners[3], box3d->corners[2]);
+
+    sp_3dbox_update_curves (box3d);
+}
+
+
+void sp_3dbox_recompute_corners (SP3DBox *box, NR::Point const A, NR::Point const B, NR::Point const C)
+{
+    sp_3dbox_move_corner_in_XY_plane (box, 2, A);
+    sp_3dbox_move_corner_in_XY_plane (box, 1, B);
+    sp_3dbox_move_corner_in_constrained_Z_direction (box, 5, C);
 }
 
+void
+sp_3dbox_update_curves (SP3DBox *box) {
+    for (int i = 0; i < 6; ++i) {
+        if (box->faces[i]) box->faces[i]->set_curve();
+    }
+}
 
 void
-sp_3dbox_compute_specific_corners (SP3DBoxContext *box3d_context, NR::Point &corner1, NR::Point &corner2, NR::Point &corner3, NR::Point &corner4)
+sp_3dbox_move_corner_in_XY_plane (SP3DBox *box, guint id, NR::Point pt)
 {
-        // TODO: Check for numerical stability and handle "wrong" cases more gracefully.
-        //       (This now mostly applies to the intersection code in the PerspectiveLine class)
-        Box3D::PerspectiveLine pl1 (box3d_context->drag_origin, Box3D::X);
-        Box3D::PerspectiveLine pl2 (box3d_context->drag_ptB, Box3D::Y);
-        corner1 = pl1.meet(pl2);
-
-        Box3D::PerspectiveLine pl3 (corner1, Box3D::Z);
-        Box3D::PerspectiveLine pl4 (box3d_context->drag_ptC, Box3D::Y);
-        corner2 = pl3.meet(pl4);
-
-        Box3D::PerspectiveLine pl5 (corner2, Box3D::X);
-        Box3D::PerspectiveLine pl6 (box3d_context->drag_origin, Box3D::Z);
-        corner3 = pl5.meet(pl6);
-
-        Box3D::PerspectiveLine pl7 (box3d_context->drag_ptC, Box3D::X);
-        Box3D::PerspectiveLine pl8 (corner3, Box3D::Y);
-        corner4 = pl7.meet(pl8);
+    NR::Point A (box->corners[id ^ Box3D::XY]);
+
+    /* set the 'front' corners */
+    box->corners[id] = pt;
+
+    Box3D::PerspectiveLine pl_one (A, Box3D::Y);
+    Box3D::PerspectiveLine pl_two (pt, Box3D::X);
+    box->corners[id ^ Box3D::X] = pl_one.meet(pl_two);
+
+    pl_one = Box3D::PerspectiveLine (A, Box3D::X);
+    pl_two = Box3D::PerspectiveLine (pt, Box3D::Y);
+    box->corners[id ^ Box3D::Y] = pl_one.meet(pl_two);
+
+    /* set the 'rear' corners */
+    NR::Point B (box->corners[id ^ Box3D::XYZ]);
+
+    pl_one = Box3D::PerspectiveLine (box->corners[id ^ Box3D::X], Box3D::Z);
+    pl_two = Box3D::PerspectiveLine (B, Box3D::Y);
+    box->corners[id ^ Box3D::XZ] = pl_one.meet(pl_two);
+
+    pl_one = Box3D::PerspectiveLine (box->corners[id ^ Box3D::XZ], Box3D::X);
+    pl_two = Box3D::PerspectiveLine (pt, Box3D::Z);
+    box->corners[id ^ Box3D::Z] = pl_one.meet(pl_two);
+
+    pl_one = Box3D::PerspectiveLine (box->corners[id ^ Box3D::Z], Box3D::Y);
+    pl_two = Box3D::PerspectiveLine (B, Box3D::X);
+    box->corners[id ^ Box3D::YZ] = pl_one.meet(pl_two);
+    
 }
 
+void
+sp_3dbox_move_corner_in_constrained_Z_direction (SP3DBox *box, guint id, NR::Point pt)
+{
+    /* set the four corners of the face containing corners[id] */
+    box->corners[id] = Box3D::PerspectiveLine (box->corners[id], Box3D::Z).closest_to(pt);
+
+    Box3D::PerspectiveLine pl_one (box->corners[id], Box3D::X);
+    Box3D::PerspectiveLine pl_two (box->corners[id ^ Box3D::XZ], Box3D::Z);
+    box->corners[id ^ Box3D::X] = pl_one.meet(pl_two);
+
+    pl_one = Box3D::PerspectiveLine (box->corners[id ^ Box3D::X], Box3D::Y);
+    pl_two = Box3D::PerspectiveLine (box->corners[id ^ Box3D::XYZ], Box3D::Z);
+    box->corners[id ^ Box3D::XY] = pl_one.meet(pl_two);
+
+    pl_one = Box3D::PerspectiveLine (box->corners[id], Box3D::Y);
+    pl_two = Box3D::PerspectiveLine (box->corners[id ^ Box3D::YZ], Box3D::Z);
+    box->corners[id ^ Box3D::Y] = pl_one.meet(pl_two);
+}
 
 
 /*
diff --git a/src/box3d.h b/src/box3d.h
index 982596d8f..1fb8280ee 100644
--- a/src/box3d.h
+++ b/src/box3d.h
@@ -34,6 +34,7 @@
 
 
 struct SP3DBox : public SPGroup {
+    NR::Point corners[8];
     Box3DFace *faces[6];
 };
 
@@ -44,6 +45,11 @@ struct SP3DBoxClass {
 GType sp_3dbox_get_type (void);
 
 void sp_3dbox_position_set (SP3DBoxContext &bc);
-void sp_3dbox_compute_specific_corners (SP3DBoxContext *box3d_context, NR::Point &corner1, NR::Point &corner2, NR::Point &corner3, NR::Point &corner4);
+void sp_3dbox_recompute_corners (SP3DBox *box, NR::Point const pt1, NR::Point const pt2, NR::Point const pt3);
+void sp_3dbox_update_curves (SP3DBox *box);
+void sp_3dbox_move_corner_in_XY_plane (SP3DBox *box, guint id, NR::Point pt);
+void sp_3dbox_move_corner_in_constrained_Z_direction (SP3DBox *box, guint id, NR::Point pt);
+
+inline NR::Point sp_3dbox_get_corner (SP3DBox *box, guint id) { return box->corners[id]; }
 
 #endif
diff --git a/src/vanishing-point.h b/src/vanishing-point.h
index 3be5d085e..b94193adc 100644
--- a/src/vanishing-point.h
+++ b/src/vanishing-point.h
@@ -28,6 +28,10 @@ enum Axis {
     X = 1,
     Y = 2,
     Z = 4,
+    XY = 3,
+    XZ = 5,
+    YZ = 6,
+    XYZ = 7,
     NONE = 0
 };