Add ability to measure the area of a plane sketch, since that's

easy and useful. Also make the volume measurement use Message(),
and not a separate text window screen.

And make Edit -> Unselect All (Esc) clear the marks drawn to
indicate free parameters, since it clears all the other temporary
stuff drawn in the graphics window.

[git-p4: depot-paths = "//depot/solvespace/": change = 2121]

graphicswin.cpp

@@ -120,6 +120,7 @@ const GraphicsWindow::MenuEntry GraphicsWindow::menu[] = {
 
 { 0, "&Analyze",                            0,                          NULL  },
 { 1, "Measure &Volume\tCtrl+Shift+V",       MNU_VOLUME,         'V'|S|C,mAna  },
+{ 1, "Measure &Area\tCtrl+Shift+A",         MNU_AREA,           'A'|S|C,mAna  },
 { 1, "Show &Interfering Parts\tCtrl+Shift+I", MNU_INTERFERENCE, 'I'|S|C,mAna  },
 { 1, "Show &Naked Edges\tCtrl+Shift+N",     MNU_NAKED_EDGES,    'N'|S|C,mAna  },
 { 1, NULL,                                  0,                          NULL  },
@@ -631,6 +632,12 @@ void GraphicsWindow::MenuEdit(int id) {
             HideTextEditControl();
             SS.nakedEdges.Clear();
             SS.justExportedInfo.draw = false;
+            // This clears the marks drawn to indicate which points are
+            // still free to drag.
+            Param *p;
+            for(p = SK.param.First(); p; p = SK.param.NextAfter(p)) {
+                p->free = false;
+            }
             break;
 
         case MNU_SELECT_ALL: {

polygon.cpp

@@ -548,6 +548,10 @@ bool SContour::IsClockwiseProjdToNormal(Vector n) {
     // what we do then.
     if(n.Magnitude() < 0.01) return true;
 
+    return (SignedAreaProjdToNormal(n) < 0);
+}
+
+double SContour::SignedAreaProjdToNormal(Vector n) {
     // An arbitrary 2d coordinate system that has n as its normal
     Vector u = n.Normal(0);
     Vector v = n.Normal(1);
@@ -561,7 +565,7 @@ bool SContour::IsClockwiseProjdToNormal(Vector n) {
 
         area += ((v0 + v1)/2)*(u1 - u0);
     }
-    return (area < 0);
+    return area;
 }
 
 bool SContour::ContainsPointProjdToNormal(Vector n, Vector p) {
@@ -621,6 +625,17 @@ Vector SPolygon::ComputeNormal(void) {
     return (l.elem[0]).ComputeNormal();
 }
 
+double SPolygon::SignedArea(void) {
+    SContour *sc;
+    double area = 0;
+    // This returns the true area only if the contours are all oriented
+    // correctly, with the holes backwards from the outer contours.
+    for(sc = l.First(); sc; sc = l.NextAfter(sc)) {
+        area += sc->SignedAreaProjdToNormal(normal);
+    }
+    return area;
+}
+
 bool SPolygon::ContainsPoint(Vector p) {
     return (WindingNumberForPoint(p) % 2) == 1;
 }

polygon.h

@@ -99,6 +99,7 @@ public:
     void MakeEdgesInto(SEdgeList *el);
     void Reverse(void);
     Vector ComputeNormal(void);
+    double SignedAreaProjdToNormal(Vector n);
     bool IsClockwiseProjdToNormal(Vector n);
     bool ContainsPointProjdToNormal(Vector n, Vector p);
     void OffsetInto(SContour *dest, double r);
@@ -125,6 +126,7 @@ public:
     Vector ComputeNormal(void);
     void AddEmptyContour(void);
     int WindingNumberForPoint(Vector p);
+    double SignedArea(void);
     bool ContainsPoint(Vector p);
     void MakeEdgesInto(SEdgeList *el);
     void FixContourDirections(void);

solvespace.cpp

@@ -630,9 +630,49 @@ void SolveSpace::MenuAnalyze(int id) {
 
                 vol += integral;
             }
-            SS.TW.shown.volume = vol;
+
-            SS.TW.GoToScreen(TextWindow::SCREEN_MESH_VOLUME);
+            char msg[1024];
-            SS.later.showTW = true;
+            sprintf(msg, "The volume of the solid model is:\n\n"
+                         "    %.3f %s^3",
+                vol / pow(SS.MmPerUnit(), 3),
+                SS.UnitName());
+
+            if(SS.viewUnits == SolveSpace::UNIT_MM) {
+                sprintf(msg+strlen(msg), "\n    %.2f mL", vol/(10*10*10));
+            }
+            strcpy(msg+strlen(msg),
+                "\n\nCurved surfaces have been approximated as triangles.\n"
+                "This introduces error, typically of around 1%.");
+            Message("%s", msg);
+            break;
+        }
+
+        case GraphicsWindow::MNU_AREA: {
+            Group *g = SK.GetGroup(SS.GW.activeGroup);
+            if(g->polyError.how != Group::POLY_GOOD) {
+                Error("This group does not contain a correctly-formed "
+                      "2d closed area. It is open, not coplanar, or self-"
+                      "intersecting.");
+                break;
+            }
+            SEdgeList sel;
+            ZERO(&sel);
+            g->polyLoops.MakeEdgesInto(&sel);
+            SPolygon sp;
+            ZERO(&sp);
+            sel.AssemblePolygon(&sp, NULL, true);
+            sp.normal = sp.ComputeNormal();
+            sp.FixContourDirections();
+            double area = sp.SignedArea();
+            double scale = SS.MmPerUnit();
+            Message("The area of the region sketched in this group is:\n\n"
+                    "    %.3f %s^2\n\n"
+                    "Curves have been approximated as piecewise linear.\n"
+                    "This introduces error, typically of around 1%%.",
+                area / (scale*scale),
+                SS.UnitName());
+            sel.Clear();
+            sp.Clear();
             break;
         }
 

textscreens.cpp

@@ -674,23 +674,6 @@ void TextWindow::ShowStepDimension(void) {
     Printf(true, "(or %Fl%Ll%fcancel operation%E)", &ScreenHome);
 }
 
-//-----------------------------------------------------------------------------
-// A report of the volume of the mesh. No interaction, output-only.
-//-----------------------------------------------------------------------------
-void TextWindow::ShowMeshVolume(void) {
-    Printf(true, "%FtMESH VOLUME");
-
-    Printf(true,  "   %3 %s^3",
-        shown.volume / pow(SS.MmPerUnit(), 3),
-        SS.UnitName());
-
-    if(SS.viewUnits == SolveSpace::UNIT_MM) {
-        Printf(false, "   %2 mL", shown.volume/(10*10*10));
-    }
-
-    Printf(true, "%Fl%Ll%f(back)%E", &ScreenHome);
-}
-
 //-----------------------------------------------------------------------------
 // The edit control is visible, and the user just pressed enter.
 //-----------------------------------------------------------------------------

textwin.cpp

@@ -234,7 +234,6 @@ void TextWindow::Show(void) {
             case SCREEN_GROUP_SOLVE_INFO:   ShowGroupSolveInfo();   break;
             case SCREEN_CONFIGURATION:      ShowConfiguration();    break;
             case SCREEN_STEP_DIMENSION:     ShowStepDimension();    break;
-            case SCREEN_MESH_VOLUME:        ShowMeshVolume();       break;
             case SCREEN_LIST_OF_STYLES:     ShowListOfStyles();     break;
             case SCREEN_STYLE_INFO:         ShowStyleInfo();        break;
             case SCREEN_PASTE_TRANSFORMED:  ShowPasteTransformed(); break;

ui.h

@@ -51,11 +51,10 @@ public:
     static const int SCREEN_GROUP_SOLVE_INFO    = 2;
     static const int SCREEN_CONFIGURATION       = 3;
     static const int SCREEN_STEP_DIMENSION      = 4;
-    static const int SCREEN_MESH_VOLUME         = 5;
+    static const int SCREEN_LIST_OF_STYLES      = 5;
-    static const int SCREEN_LIST_OF_STYLES      = 6;
+    static const int SCREEN_STYLE_INFO          = 6;
-    static const int SCREEN_STYLE_INFO          = 7;
+    static const int SCREEN_PASTE_TRANSFORMED   = 7;
-    static const int SCREEN_PASTE_TRANSFORMED   = 8;
+    static const int SCREEN_EDIT_VIEW           = 8;
-    static const int SCREEN_EDIT_VIEW           = 9;
     typedef struct {
         int         screen;
 
@@ -74,8 +73,6 @@ public:
             Vector      origin;
             double      scale;
         }           paste;
-        
-        double      volume;
     } ShownState;
     ShownState shown;
 
@@ -149,7 +146,6 @@ public:
     void ShowListOfStyles(void);
     void ShowStyleInfo(void);
     void ShowStepDimension(void);
-    void ShowMeshVolume(void);
     void ShowPasteTransformed(void);
     void ShowEditView(void);
     // Special screen, based on selection
@@ -330,6 +326,7 @@ public:
         MNU_COMMENT,
         // Analyze
         MNU_VOLUME,
+        MNU_AREA,
         MNU_INTERFERENCE,
         MNU_NAKED_EDGES,
         MNU_SHOW_DOF,

wishlist.txt

@@ -1,7 +1,6 @@
 replace show/hide links with icons
 add checked/unchecked checkbox and radio button
 fix bug with rotation in plane where green line stays displayed
-area of sketch in a given workplane (easy, useful)
 lock point where dragged constraint
 remove toolbar icons for sketch in 3d, add View -> Align to Workplane