Add tangency constraints, for line segments against arcs or cubics.

These are just a convenience, since it would be possible to get the
same result by drawing a construction line.

[git-p4: depot-paths = "//depot/solvespace/": change = 1836]

constraint.cpp

@@ -31,6 +31,8 @@ char *Constraint::DescriptionString(void) {
         case SAME_ORIENTATION:  s = "same-orientation"; break;
         case ANGLE:             s = "angle"; break;
         case PARALLEL:          s = "parallel"; break;
+        case ARC_LINE_TANGENT:  s = "arc-line-tangent"; break;
+        case CUBIC_LINE_TANGENT:s = "cubic-line-tangent"; break;
         case PERPENDICULAR:     s = "perpendicular"; break;
         case EQUAL_RADIUS:      s = "eq-radius"; break;
         case COMMENT:           s = "comment"; break;
@@ -378,7 +380,7 @@ void Constraint::MenuConstrain(int id) {
             if(gs.constraints == 1 && gs.n == 0) {
                 Constraint *c = SS.GetConstraint(gs.constraint[0]);
                 if(c->type == ANGLE) {
-                    c->otherAngle = !(c->otherAngle);
+                    c->other = !(c->other);
                     c->ModifyToSatisfy();
                     break;
                 }
@@ -405,7 +407,7 @@ void Constraint::MenuConstrain(int id) {
                 c.entityA = gs.vector[0];
                 c.entityB = gs.vector[1];
                 c.valA = 0;
-                c.otherAngle = true;
+                c.other = true;
             } else {
                 Error("Bad selection for angle constraint.");
                 return;
@@ -419,8 +421,56 @@ void Constraint::MenuConstrain(int id) {
                 c.type = PARALLEL;
                 c.entityA = gs.vector[0];
                 c.entityB = gs.vector[1];
+            } else if(gs.lineSegments == 1 && gs.arcs == 1 && gs.n == 2) {
+                Entity *line = SS.GetEntity(gs.entity[0]);
+                Entity *arc  = SS.GetEntity(gs.entity[1]);
+                if(line->type == Entity::ARC_OF_CIRCLE) {
+                    SWAP(Entity *, line, arc);
+                }
+                Vector l0 = SS.GetEntity(line->point[0])->PointGetNum(),
+                       l1 = SS.GetEntity(line->point[1])->PointGetNum();
+                Vector a1 = SS.GetEntity(arc->point[1])->PointGetNum(),
+                       a2 = SS.GetEntity(arc->point[2])->PointGetNum();
+
+                if(l0.Equals(a1) || l1.Equals(a1)) {
+                    c.other = false;
+                } else if(l0.Equals(a2) || l1.Equals(a2)) {
+                    c.other = true;
                 } else {
-                Error("Bad selection for parallel constraint.");
+                    Error("The tangent arc and line segment must share an "
+                          "endpoint. Constrain them with Constrain -> "
+                          "On Point before constraining tangent.");
+                    return;
+                }
+                c.type = ARC_LINE_TANGENT;
+                c.entityA = arc->h;
+                c.entityB = line->h;
+            } else if(gs.lineSegments == 1 && gs.cubics == 1 && gs.n == 2) {
+                Entity *line  = SS.GetEntity(gs.entity[0]);
+                Entity *cubic = SS.GetEntity(gs.entity[1]);
+                if(line->type == Entity::CUBIC) {
+                    SWAP(Entity *, line, cubic);
+                }
+                Vector l0 = SS.GetEntity(line->point[0])->PointGetNum(),
+                       l1 = SS.GetEntity(line->point[1])->PointGetNum();
+                Vector a0 = SS.GetEntity(cubic->point[0])->PointGetNum(),
+                       a3 = SS.GetEntity(cubic->point[3])->PointGetNum();
+
+                if(l0.Equals(a0) || l1.Equals(a0)) {
+                    c.other = false;
+                } else if(l0.Equals(a3) || l1.Equals(a3)) {
+                    c.other = true;
+                } else {
+                    Error("The tangent cubic and line segment must share an "
+                          "endpoint. Constrain them with Constrain -> "
+                          "On Point before constraining tangent.");
+                    return;
+                }
+                c.type = CUBIC_LINE_TANGENT;
+                c.entityA = cubic->h;
+                c.entityB = line->h;
+            } else {
+                Error("Bad selection for parallel / tangent constraint.");
                 return;
             }
             AddConstraint(&c);
@@ -563,7 +613,7 @@ void Constraint::ModifyToSatisfy(void) {
     if(type == ANGLE) {
         Vector a = SS.GetEntity(entityA)->VectorGetNum();
         Vector b = SS.GetEntity(entityB)->VectorGetNum();
-        if(otherAngle) a = a.ScaledBy(-1);
+        if(other) a = a.ScaledBy(-1);
         if(workplane.v != Entity::FREE_IN_3D.v) {
             a = a.ProjectVectorInto(workplane);
             b = b.ProjectVectorInto(workplane);
@@ -961,7 +1011,7 @@ void Constraint::GenerateReal(IdList<Equation,hEquation> *l) {
             Entity *b = SS.GetEntity(entityB);
             ExprVector ae = a->VectorGetExprs();
             ExprVector be = b->VectorGetExprs();
-            if(otherAngle) ae = ae.ScaledBy(Expr::From(-1));
+            if(other) ae = ae.ScaledBy(Expr::From(-1));
             Expr *c;
             if(workplane.v == Entity::FREE_IN_3D.v) {
                 Expr *mags = (ae.Magnitude())->Times(be.Magnitude());
@@ -992,6 +1042,45 @@ void Constraint::GenerateReal(IdList<Equation,hEquation> *l) {
             break;
         }
 
+        case ARC_LINE_TANGENT: {
+            Entity *arc  = SS.GetEntity(entityA);
+            Entity *line = SS.GetEntity(entityB);
+
+            ExprVector ac = SS.GetEntity(arc->point[0])->PointGetExprs();
+            ExprVector ap = 
+                SS.GetEntity(arc->point[other ? 2 : 1])->PointGetExprs();
+
+            ExprVector ld = line->VectorGetExprs();
+
+            // The line is perpendicular to the radius
+            AddEq(l, ld.Dot(ac.Minus(ap)), 0);
+            break;
+        }
+
+        case CUBIC_LINE_TANGENT: {
+            Entity *cubic = SS.GetEntity(entityA);
+            Entity *line  = SS.GetEntity(entityB);
+            
+            ExprVector endpoint =
+                SS.GetEntity(cubic->point[other ? 3 : 0])->PointGetExprs();
+            ExprVector ctrlpoint = 
+                SS.GetEntity(cubic->point[other ? 2 : 1])->PointGetExprs();
+            
+            ExprVector a = endpoint.Minus(ctrlpoint);
+
+            ExprVector b = line->VectorGetExprs();
+
+            if(workplane.v == Entity::FREE_IN_3D.v) {
+                AddEq(l, VectorsParallel(0, a, b), 0);
+                AddEq(l, VectorsParallel(1, a, b), 1);
+            } else {
+                Entity *w = SS.GetEntity(workplane);
+                ExprVector wn = w->Normal()->NormalExprsN();
+                AddEq(l, (a.Cross(b)).Dot(wn), 0);
+            }
+            break;
+        }
+
         case PARALLEL: {
             Entity *ea = SS.GetEntity(entityA), *eb = SS.GetEntity(entityB);
             if(eb->group.v != group.v) {

draw.cpp

@@ -791,8 +791,13 @@ void GraphicsWindow::GroupSelection(void) {
             switch(e->type) {
                 case Entity::WORKPLANE:     (gs.workplanes)++; break;
                 case Entity::LINE_SEGMENT:  (gs.lineSegments)++; break;
+                case Entity::CUBIC:         (gs.cubics)++; break;
 
                 case Entity::ARC_OF_CIRCLE:
+                    (gs.circlesOrArcs)++;
+                    (gs.arcs)++;
+                    break;
+
                 case Entity::CIRCLE:        (gs.circlesOrArcs)++; break;
             }
         }

drawconstraint.cpp

@@ -305,7 +305,7 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
             Vector b0 = b->VectorGetRefPoint();
             Vector da = a->VectorGetNum();
             Vector db = b->VectorGetNum();
-            if(otherAngle) da = da.ScaledBy(-1);
+            if(other) da = da.ScaledBy(-1);
 
             if(workplane.v != Entity::FREE_IN_3D.v) {
                 a0 = a0.ProjectInto(workplane);
@@ -411,6 +411,55 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
             break;
         }
 
+        case CUBIC_LINE_TANGENT:
+        case ARC_LINE_TANGENT: {
+            Vector textAt, u, v;
+
+            if(type == ARC_LINE_TANGENT) {
+                Entity *arc = SS.GetEntity(entityA);
+                Entity *norm = SS.GetEntity(arc->normal);
+                Vector c = SS.GetEntity(arc->point[0])->PointGetNum();
+                Vector p = 
+                    SS.GetEntity(arc->point[other ? 2 : 1])->PointGetNum();
+                Vector r = p.Minus(c);
+                textAt = p.Plus(r.WithMagnitude(14/SS.GW.scale));
+                u = norm->NormalU();
+                v = norm->NormalV();
+            } else {
+                Vector n;
+                if(workplane.v == Entity::FREE_IN_3D.v) {
+                    u = gr;
+                    v = gu;
+                    n = gn;
+                } else {
+                    Entity *wn = SS.GetEntity(workplane)->Normal();
+                    u = wn->NormalU();
+                    v = wn->NormalV();
+                    n = wn->NormalN();
+                }
+
+                Entity *cubic = SS.GetEntity(entityA);
+                Vector p =
+                    SS.GetEntity(cubic->point[other ? 3 : 0])->PointGetNum();
+                Vector dir = SS.GetEntity(entityB)->VectorGetNum();
+                Vector out = n.Cross(dir);
+                textAt = p.Plus(out.WithMagnitude(14/SS.GW.scale));
+            }
+
+            if(dogd.drawing) {
+                glPushMatrix();
+                    glxTranslatev(textAt);
+                    glxOntoWorkplane(u, v);
+                    glxWriteTextRefCenter("T");
+                glPopMatrix();
+            } else {
+                dogd.refp = textAt;
+                Point2d ref = SS.GW.ProjectPoint(dogd.refp);
+                dogd.dmin = min(dogd.dmin, ref.DistanceTo(dogd.mp)-10);
+            }
+            break;
+        }
+
         case PARALLEL: {
             for(int i = 0; i < 2; i++) {
                 Entity *e = SS.GetEntity(i == 0 ? entityA : entityB);

file.cpp

@@ -132,7 +132,7 @@ const SolveSpace::SaveTable SolveSpace::SAVED[] = {
     { 'c',  "Constraint.ptC.v",         'x',    &(SS.sv.c.ptC.v)              },
     { 'c',  "Constraint.entityA.v",     'x',    &(SS.sv.c.entityA.v)          },
     { 'c',  "Constraint.entityB.v",     'x',    &(SS.sv.c.entityB.v)          },
-    { 'c',  "Constraint.otherAngle",    'b',    &(SS.sv.c.otherAngle)         },
+    { 'c',  "Constraint.other",         'b',    &(SS.sv.c.other)              },
     { 'c',  "Constraint.reference",     'b',    &(SS.sv.c.reference)          },
     { 'c',  "Constraint.comment",       'N',    &(SS.sv.c.comment)            },
     { 'c',  "Constraint.disp.offset.x", 'f',    &(SS.sv.c.disp.offset.x)      },

graphicswin.cpp

@@ -25,11 +25,11 @@ const GraphicsWindow::MenuEntry GraphicsWindow::menu[] = {
 { 0, "&Edit",                               0,                          NULL  },
 { 1, "&Undo\tCtrl+Z",                       MNU_UNDO,           'Z'|C,  mEdit },
 { 1, "&Redo\tCtrl+Y",                       MNU_REDO,           'Y'|C,  mEdit },
+{ 1, "Re&generate All\tSpace",              MNU_REGEN_ALL,      ' ',    mEdit },
 { 1,  NULL,                                 0,                          NULL  },
 { 1, "&Delete\tDel",                        MNU_DELETE,         127,    mEdit },
 { 1,  NULL,                                 0,                          NULL  },
 { 1, "&Unselect All\tEsc",                  MNU_UNSELECT_ALL,   27,     mEdit },
-{ 1, "Re&generate All\tSpace",              MNU_REGEN_ALL,      ' ',    mEdit },
 
 { 0, "&View",                               0,                          NULL  },
 { 1, "Zoom &In\t+",                         MNU_ZOOM_IN,        '+',    mView },
@@ -87,7 +87,7 @@ const GraphicsWindow::MenuEntry GraphicsWindow::menu[] = {
 { 1, "Length Ra&tio\tZ",                    MNU_RATIO,          'Z',    mCon  },
 { 1, "At &Midpoint\tM",                     MNU_AT_MIDPOINT,    'M',    mCon  },
 { 1, "S&ymmetric\tY",                       MNU_SYMMETRIC,      'Y',    mCon  },
-{ 1, "Para&llel\tL",                        MNU_PARALLEL,       'L',    mCon  },
+{ 1, "Para&llel / Tangent\tL",              MNU_PARALLEL,       'L',    mCon  },
 { 1, "&Perpendicular\t[",                   MNU_PERPENDICULAR,  '[',    mCon  },
 { 1, "Same Orient&ation\tX",                MNU_ORIENTED_SAME,  'X',    mCon  },
 { 1, NULL,                                  0,                          NULL  },

mesh.cpp

@@ -619,7 +619,7 @@ void SKdNode::MakeCertainEdgesInto(SEdgeList *sel, bool emphasized) {
             FindEdgeOn(a, b, &n, &nOther, tr->meta, cnt++);
             if(n != 1) {
                 if(!emphasized) {
-                    sel->AddEdge(a, b);
+                    if(n == 0) sel->AddEdge(a, b);
                 } else {
                     dbp("hanging: n=%d (%.3f %.3f %.3f)  (%.3f %.3f %.3f)", 
                         n, CO(a), CO(b));

sketch.h

@@ -463,6 +463,8 @@ public:
     static const int ANGLE              = 120;
     static const int PARALLEL           = 121;
     static const int PERPENDICULAR      = 122;
+    static const int ARC_LINE_TANGENT   = 123;
+    static const int CUBIC_LINE_TANGENT = 124;
     static const int EQUAL_RADIUS       = 130;
 
     static const int COMMENT            = 1000;
@@ -482,7 +484,7 @@ public:
     hEntity     ptC;
     hEntity     entityA;
     hEntity     entityB;
-    bool        otherAngle;
+    bool        other;
 
     bool        reference; // a ref dimension, that generates no eqs
 

ui.h

@@ -316,6 +316,8 @@ public:
         int         faces;
         int         lineSegments;
         int         circlesOrArcs;
+        int         arcs;
+        int         cubics;
         int         anyNormals;
         int         vectors;
         int         constraints;