Add a function to combine vertices while tesselating the polygon,

so that OpenGL can fill self-intersecting polygons.

[git-p4: depot-paths = "//depot/solvespace/": change = 1688]

expr.h

@@ -53,6 +53,9 @@ public:
         char    c;
     }       x;
 
+    static inline Expr *AllocExpr(void)
+        { return (Expr *)AllocTemporary(sizeof(Expr)); }
+
     static Expr *FromParam(hParam p);
     static Expr *FromConstant(double v);
 

glhelper.cpp

@@ -82,6 +82,16 @@ void glxColor4d(double r, double g, double b, double a)
 static void __stdcall Vertex(Vector *p) {
     glxVertex3v(*p);
 }
+static void __stdcall Combine(double coords[3], void *vertexData[4],
+                                float weight[4], void **outData)
+{
+    Vector *n = (Vector *)AllocTemporary(sizeof(Vector));
+    n->x = coords[0];
+    n->y = coords[1];
+    n->z = coords[2];
+
+    *outData = n;
+}
 void glxFillPolygon(SPolygon *p)
 {
     int i, j;
@@ -91,6 +101,7 @@ void glxFillPolygon(SPolygon *p)
     gluTessCallback(gt, GLU_TESS_BEGIN, (cf *)glBegin);
     gluTessCallback(gt, GLU_TESS_END, (cf *)glEnd);
     gluTessCallback(gt, GLU_TESS_VERTEX, (cf *)Vertex);
+    gluTessCallback(gt, GLU_TESS_COMBINE, (cf *)Combine);
     gluTessProperty(gt, GLU_TESS_WINDING_RULE, GLU_TESS_WINDING_ODD);
 
     gluTessBeginPolygon(gt, NULL);

solvespace.cpp

@@ -102,7 +102,7 @@ bool SolveSpace::SolveGroup(hGroup hg) {
     }
 
     bool r = sys.Solve();
-    FreeAllExprs();
+    FreeAllTemporary();
     return r;
 }
 

solvespace.h

@@ -48,8 +48,8 @@ void PaintGraphics(void);
 void dbp(char *str, ...);
 void Error(char *str, ...);
 
-Expr *AllocExpr(void);
+void *AllocTemporary(int n);
-void FreeAllExprs(void);
+void FreeAllTemporary(void);
 void *MemRealloc(void *p, int n);
 void *MemAlloc(int n);
 void MemFree(void *p);

win32/w32main.cpp

@@ -69,15 +69,14 @@ void Error(char *str, ...)
 // at the end.
 //-----------------------------------------------------------------------------
 static HANDLE Heap;
-Expr *AllocExpr(void)
+void *AllocTemporary(int n)
 {
-    Expr *v = (Expr *)HeapAlloc(Heap, HEAP_NO_SERIALIZE | HEAP_ZERO_MEMORY, 
+    Expr *v = (Expr *)HeapAlloc(Heap, HEAP_NO_SERIALIZE | HEAP_ZERO_MEMORY, n);
-                                                                 sizeof(Expr));
     if(!v) oops();
-    memset(v, 0, sizeof(*v));
+    memset(v, 0, n);
     return v;
 }
-void FreeAllExprs(void)
+void FreeAllTemporary(void)
 {
     if(Heap) HeapDestroy(Heap);
     Heap = HeapCreate(HEAP_NO_SERIALIZE, 1024*1024*20, 0);
@@ -735,8 +734,8 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
     ThawWindowPos(TextWnd);
     ThawWindowPos(GraphicsWnd);
 
-    // Create the heap that we use to store Exprs.
+    // Create the heap that we use to store Exprs and other temp stuff.
-    FreeAllExprs();
+    FreeAllTemporary();
 
     // Call in to the platform-independent code, and let them do their init
     SS.Init(lpCmdLine);