Report the number of degrees of freedom for each group.

[git-p4: depot-paths = "//depot/solvespace/": change = 1834]

graphicswin.cpp

@@ -476,6 +476,7 @@ void GraphicsWindow::MenuEdit(int id) {
         case MNU_REGEN_ALL:
             SS.ReloadAllImported();
             SS.GenerateAll(0, INT_MAX);
+            SS.later.showTW = true;
             break;
 
         default: oops();

sketch.h

@@ -104,6 +104,7 @@ public:
     static const int SINGULAR_JACOBIAN    = 11;
     struct {
         int                 how;
+        int                 dof;
         SList<hConstraint>  remove;
     } solved;
 

system.cpp

@@ -440,9 +440,14 @@ void System::Solve(Group *g) {
     if(rank != mat.m) {
         FindWhichToRemoveToFixJacobian(g);
         g->solved.how = Group::SINGULAR_JACOBIAN;
+        g->solved.dof = 0;
         TextWindow::ReportHowGroupSolved(g->h);
         return;
     }
+    // This is not the full Jacobian, but any substitutions or single-eq
+    // solves removed one equation and one unknown, therefore no effect
+    // on the number of DOF.
+    g->solved.dof = mat.n - mat.m;
 
     // And do the leftovers as one big system
     if(!NewtonSolve(0)) {

textscreens.cpp

@@ -439,7 +439,7 @@ void TextWindow::ShowGroupInfo(void) {
     if(a == 0) Printf(false, "%Ba   (none)");
 
     a = 0;
-    Printf(true, "%Ftconstraints in group");
+    Printf(true, "%Ftconstraints in group (%d DOF)", g->solved.dof);
     for(i = 0; i < SS.constraint.n; i++) {
         Constraint *c = &(SS.constraint.elem[i]);