When deleting a request, rewrite the constraints on its points in

such a way as to keep all the points that used to be coincident,
still coincident.

[git-p4: depot-paths = "//depot/solvespace/": change = 2013]

graphicswin.cpp

@@ -558,6 +558,14 @@ void GraphicsWindow::ForceTextWindowShown(void) {
 }
 
 void GraphicsWindow::DeleteTaggedRequests(void) {
+    // Rewrite any point-coincident constraints that were affected by this
+    // deletion.
+    Request *r;
+    for(r = SK.request.First(); r; r = SK.request.NextAfter(r)) {
+        if(!r->tag) continue;
+        FixConstraintsForRequestBeingDeleted(r->h);
+    }
+    // and then delete the tagged requests.
     SK.request.RemoveTagged();
 
     // An edit might be in progress for the just-deleted item. So

modify.cpp

@@ -16,6 +16,62 @@ void GraphicsWindow::ReplacePointInConstraints(hEntity oldpt, hEntity newpt) {
     }
 }
 
+
+void GraphicsWindow::FixConstraintsForRequestBeingDeleted(hRequest hr) {
+    Request *r = SK.GetRequest(hr);
+    if(r->group.v != SS.GW.activeGroup.v) return;
+
+    Entity *e;
+    for(e = SK.entity.First(); e; e = SK.entity.NextAfter(e)) {
+        if(!(e->h.isFromRequest())) continue;
+        if(e->h.request().v != hr.v) continue;
+
+        if(e->type != Entity::POINT_IN_2D &&
+           e->type != Entity::POINT_IN_3D)
+        {
+            continue;
+        }
+
+        // This is a point generated by the request being deleted; so fix
+        // the constraints for that.
+        FixConstraintsForPointBeingDeleted(e->h);
+    }
+}
+void GraphicsWindow::FixConstraintsForPointBeingDeleted(hEntity hpt) {
+    List<hEntity> ld;
+    ZERO(&ld);
+
+    Constraint *c;
+    SK.constraint.ClearTags();
+    for(c = SK.constraint.First(); c; c = SK.constraint.NextAfter(c)) {
+        if(c->type != Constraint::POINTS_COINCIDENT) continue;
+        if(c->group.v != SS.GW.activeGroup.v) continue;
+
+        if(c->ptA.v == hpt.v) {
+            ld.Add(&(c->ptB));
+            c->tag = 1;
+        }
+        if(c->ptB.v == hpt.v) {
+            ld.Add(&(c->ptA));
+            c->tag = 1;
+        }
+    }
+    // These would get removed anyways when we regenerated, but do it now;
+    // that way subsequent calls of this function (if multiple coincident
+    // points are getting deleted) will work correctly.
+    SK.constraint.RemoveTagged();
+
+    // If more than one point was constrained coincident with hpt, then
+    // those two points were implicitly coincident with each other. By
+    // deleting hpt (and all constraints that mention it), we will delete
+    // that relationship. So put it back here now.
+    int i;
+    for(i = 1; i < ld.n; i++) {
+        Constraint::ConstrainCoincident(ld.elem[i-1], ld.elem[i]);
+    }
+    ld.Clear();
+}
+
 //-----------------------------------------------------------------------------
 // A single point must be selected when this function is called. We find two
 // non-construction line segments that join at this point, and create a
@@ -273,7 +329,7 @@ hEntity GraphicsWindow::SplitCubic(hEntity he, Vector pinter) {
     SK.GetEntity(ei1->point[3])->PointForceTo(bi1.ctrl[3]);
 
     ReplacePointInConstraints(hep0, e0i->point[0]);
-    ReplacePointInConstraints(hep1, ei1->point[3]);
+    ReplacePointInConstraints(hep3, ei1->point[3]);
     Constraint::ConstrainCoincident(e0i->point[3], ei1->point[0]);
     return e0i->point[3];
 }

ui.h

@@ -352,6 +352,8 @@ public:
     hEntity SplitCircle(hEntity he, Vector pinter);
     hEntity SplitCubic(hEntity he, Vector pinter);
     void ReplacePointInConstraints(hEntity oldpt, hEntity newpt);
+    void FixConstraintsForRequestBeingDeleted(hRequest hr);
+    void FixConstraintsForPointBeingDeleted(hEntity hpt);
     
     // The current selection.
     class Selection {