Add symmetric about line constraint. This applies only when locked

in a workplane, since it would otherwise be ambiguous.

[git-p4: depot-paths = "//depot/solvespace/": change = 1817]

constraint.cpp

@@ -22,6 +22,7 @@ char *Constraint::DescriptionString(void) {
         case SYMMETRIC:         s = "symmetric"; break;
         case SYMMETRIC_HORIZ:   s = "symmetric-h"; break;
         case SYMMETRIC_VERT:    s = "symmetric-v"; break;
+        case SYMMETRIC_LINE:    s = "symmetric-line"; break;
         case AT_MIDPOINT:       s = "at-midpoint"; break;
         case HORIZONTAL:        s = "horizontal"; break;
         case VERTICAL:          s = "vertical"; break;
@@ -70,7 +71,7 @@ void Constraint::ConstrainCoincident(hEntity ptA, hEntity ptB) {
 
 void Constraint::MenuConstrain(int id) {
     Constraint c;
-    memset(&c, 0, sizeof(c));
+    ZERO(&c);
     c.group = SS.GW.activeGroup;
     c.workplane = SS.GW.ActiveWorkplane();
 
@@ -235,11 +236,37 @@ void Constraint::MenuConstrain(int id) {
                 c.entityA = gs.entity[1-i];
                 c.ptA = line->point[0];
                 c.ptB = line->point[1];
+            } else if(SS.GW.LockedInWorkplane()
+                        && gs.lineSegments == 2 && gs.n == 2)
+            {
+                Entity *l0 = SS.GetEntity(gs.entity[0]),
+                       *l1 = SS.GetEntity(gs.entity[1]);
+
+                if((l1->group.v != SS.GW.activeGroup.v) ||
+                   (l1->construction && !(l0->construction)))
+                {
+                    SWAP(Entity *, l0, l1);
+                }
+                c.ptA = l1->point[0];
+                c.ptB = l1->point[1];
+                c.entityA = l0->h;
+                c.type = SYMMETRIC_LINE;
+            } else if(SS.GW.LockedInWorkplane()
+                        && gs.lineSegments == 1 && gs.points == 2 && gs.n == 3)
+            {
+                c.ptA = gs.point[0];
+                c.ptB = gs.point[1];
+                c.entityA = gs.entity[0];
+                c.type = SYMMETRIC_LINE;
             } else {
                 Error("Bad selection for symmetric constraint.");
                 return;
             }
-            if(c.entityA.v == Entity::NO_ENTITY.v) {
+            if(c.type != 0) {
+                // Already done, symmetry about a line segment in a workplane
+            } else if(c.entityA.v == Entity::NO_ENTITY.v) {
+                // Horizontal / vertical symmetry, implicit symmetry plane
+                // normal to the workplane
                 if(c.workplane.v == Entity::FREE_IN_3D.v) {
                     Error("Must be locked in to workplane when constraining "
                           "symmetric without an explicit symmetry plane.");
@@ -832,6 +859,39 @@ void Constraint::GenerateReal(IdList<Equation,hEquation> *l) {
             break;
         }
 
+        case SYMMETRIC_LINE: {
+            Entity *pa = SS.GetEntity(ptA);
+            Entity *pb = SS.GetEntity(ptB);
+
+            Expr *pau, *pav, *pbu, *pbv;
+            pa->PointGetExprsInWorkplane(workplane, &pau, &pav);
+            pb->PointGetExprsInWorkplane(workplane, &pbu, &pbv);
+
+            Entity *ln = SS.GetEntity(entityA);
+            Entity *la = SS.GetEntity(ln->point[0]);
+            Entity *lb = SS.GetEntity(ln->point[1]);
+            Expr *lau, *lav, *lbu, *lbv;
+            la->PointGetExprsInWorkplane(workplane, &lau, &lav);
+            lb->PointGetExprsInWorkplane(workplane, &lbu, &lbv);
+
+            Expr *dpu = pbu->Minus(pau), *dpv = pbv->Minus(pav);
+            Expr *dlu = lbu->Minus(lau), *dlv = lbv->Minus(lav);
+
+            // The line through the points is perpendicular to the line
+            // of symmetry.
+            AddEq(l, (dlu->Times(dpu))->Plus(dlv->Times(dpv)), 0);
+
+            // And the signed distances of the points to the line are
+            // equal in magnitude and opposite in sign, so sum to zero
+            Expr *dista = (dlv->Times(lau->Minus(pau)))->Minus(
+                          (dlu->Times(lav->Minus(pav))));
+            Expr *distb = (dlv->Times(lau->Minus(pbu)))->Minus(
+                          (dlu->Times(lav->Minus(pbv))));
+            AddEq(l, dista->Plus(distb), 1);
+
+            break;
+        }
+
         case HORIZONTAL:
         case VERTICAL: {
             hEntity ha, hb;

drawconstraint.cpp

@@ -491,9 +491,21 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
             n = SS.GetEntity(workplane)->Normal()->NormalU(); goto s;
         case SYMMETRIC_VERT:
             n = SS.GetEntity(workplane)->Normal()->NormalV(); goto s;
+        case SYMMETRIC_LINE: {
+            Entity *ln = SS.GetEntity(entityA);
+            Vector la = SS.GetEntity(ln->point[0])->PointGetNum(),
+                   lb = SS.GetEntity(ln->point[1])->PointGetNum();
+            la = la.ProjectInto(workplane);
+            lb = lb.ProjectInto(workplane);
+            n = lb.Minus(la);
+            Vector nw = SS.GetEntity(workplane)->Normal()->NormalN();
+            n = n.RotatedAbout(nw, PI/2);
+            goto s;
+        }
 s:
             Vector a = SS.GetEntity(ptA)->PointGetNum();
             Vector b = SS.GetEntity(ptB)->PointGetNum();
+
             for(int i = 0; i < 2; i++) {
                 Vector tail = (i == 0) ? a : b;
                 Vector d = (i == 0) ? b : a;

sketch.h

@@ -447,6 +447,7 @@ public:
     static const int SYMMETRIC          =  60;
     static const int SYMMETRIC_HORIZ    =  61;
     static const int SYMMETRIC_VERT     =  62;
+    static const int SYMMETRIC_LINE     =  63;
     static const int AT_MIDPOINT        =  70;
     static const int HORIZONTAL         =  80;
     static const int VERTICAL           =  81;

textscreens.cpp

@@ -463,10 +463,11 @@ void TextWindow::ShowGroupInfo(void) {
 
         if(c->group.v == shown->group.v) {
             char *s = c->DescriptionString();
-            Printf(false, "%Bp   %Fl%Ll%D%f%h%s%E",
+            Printf(false, "%Bp   %Fl%Ll%D%f%h%s%E %s",
                 (a & 1) ? 'd' : 'a',
                 c->h.v, (&TextWindow::ScreenSelectConstraint),
-                (&TextWindow::ScreenHoverConstraint), s);
+                (&TextWindow::ScreenHoverConstraint), s,
+                c->reference ? "(ref)" : "");
             a++;
         }
     }

wishlist.txt

@@ -8,7 +8,7 @@ auto-generate circles and faces when lathing
 copy the section geometry to other end when sweeping
 cylindrical faces
 draw explicit edges
-symmetric about line segment
+perpendicular constraint
 
 
 long term