Extra params for TriangulatePolygon

Villavu · Jul 27, 2024 · 273ca49 · 273ca49
1 parent a03dd46
commit 273ca49
Show file tree

Hide file tree

Showing 2 changed files with 19 additions and 10 deletions.
diff --git a/Source/script/imports/simba.import_math.pas b/Source/script/imports/simba.import_math.pas
@@ -217,17 +217,22 @@ procedure _LapeIsConvexPolygon(const Params: PParamArray; const Result: Pointer)
 (*
 TriangulatePolygon
 -----------
-> function TriangulatePolygon(Polygon: TPointArray): TTriangleArray;
+> function TriangulatePolygon(Polygon: TPointArray; MinArea: Double=0; MaxDepth: Int32=0): TTriangleArray;
 
 Break the polygon into triangles, the smallest possible polygon. The order of the
 input does matter, if it fails, try to reverse the Poly with Poly.Reversed()
 
 This is a custom algorithm by slacky, based around the concept of trimming "ears",
 if you dont like the output, you may have more luck with rolling the Polygon before calling.
+
+Two default params exists as well, `MinArea` and `MaxDepth`, they work in tandom,
+`MinArea` parameter is for setting a minimum size of triangles added to result, and as this method
+works iteratively, removing triangles in a circle around the shape over and over, `MaxDepth` refers
+to the max number of rounds it has moved around the shape before it ignores `MinArea` paramater.
 *)
 procedure _LapeTriangulatePolygon(const Params: PParamArray; const Result: Pointer); LAPE_WRAPPER_CALLING_CONV
 begin
-  PTriangleArray(Result)^ := TSimbaGeometry.TriangulatePolygon(PPointArray(Params^[0])^);
+  PTriangleArray(Result)^ := TSimbaGeometry.TriangulatePolygon(PPointArray(Params^[0])^, PSingle(Params^[1])^, PInt32(Params^[2])^);
 end;
 
 (*
@@ -428,7 +433,7 @@ procedure ImportMath(Compiler: TSimbaScript_Compiler);
     addGlobalFunc('function Modulo(const X, Y: Double): Double; overload', @_LapeModuloF);
 
     addGlobalFunc('function IsConvexPolygon(const Polygon: TPointArray): Boolean', @_LapeIsConvexPolygon);
-    addGlobalFunc('function TriangulatePolygon(const Polygon: TPointArray): TTriangleArray', @_LapeTriangulatePolygon);
+    addGlobalFunc('function TriangulatePolygon(const Polygon: TPointArray; MinArea: Single=0; MaxDepth: Int32=0): TTriangleArray', @_LapeTriangulatePolygon);
     addGlobalFunc('function LineInPolygon(a1, a2: TPoint; const Polygon: TPointArray): Boolean', @_LapeLineInPolygon);
 
     addGlobalFunc('function DeltaAngle(const DegreesA, DegreesB: Double; R: Double = 360): Double', @_LapeDeltaAngle);

diff --git a/Source/simba.geometry.pas b/Source/simba.geometry.pas
@@ -48,7 +48,7 @@   TSimbaGeometry = class
 
     class function IsConvexPolygon(const Polygon: TPointArray): Boolean;
     class function LineInPolygon(a1, a2: TPoint; const Polygon: TPointArray): Boolean;
-    class function TriangulatePolygon(Polygon: TPointArray): TTriangleArray;
+    class function TriangulatePolygon(Polygon: TPointArray; MinArea: Single=0; MaxDepth: Int32=0): TTriangleArray;
     class function PolygonArea(const Polygon: TPointArray): Double; static; inline;
     class function ExpandPolygon(const Polygon: TPointArray; Amount: Integer): TPointArray; static;
     class function CrossProduct(const r, p, q: TPoint): Int64; static; overload; inline;
@@ -394,9 +394,9 @@ class function TSimbaGeometry.LineInPolygon(a1, a2: TPoint; const Polygon: TPoin
   Result := True;
 end; 
 
-class function TSimbaGeometry.TriangulatePolygon(Polygon: TPointArray): TTriangleArray;
+class function TSimbaGeometry.TriangulatePolygon(Polygon: TPointArray; MinArea: Single=0; MaxDepth: Int32=0): TTriangleArray;
 var
-  i,rshift: Int32;
+  i,j,rshift: Int32;
   A,B,C: TPoint;
   tmp1,tmp2: TPointArray;
   valid: Boolean;
@@ -407,6 +407,7 @@ class function TSimbaGeometry.TriangulatePolygon(Polygon: TPointArray): TTriangl
   rshift := 0;
   while Length(tmp1) > 3 do
   begin
+    Inc(j);
     valid := False;
     i := 0;
     rshift := 0;
@@ -418,10 +419,13 @@ class function TSimbaGeometry.TriangulatePolygon(Polygon: TPointArray): TTriangl
 
       if (CrossProduct(A,B,C) >= 0) and LineInPolygon(A,C, Polygon) then
       begin
-        SetLength(Result, Length(Result)+1);
-        Result[High(Result)].A := A;
-        Result[High(Result)].B := B;
-        Result[High(Result)].C := C;
+        if (j >= MaxDepth) or (PolygonArea([A,B,C]) > MinArea) then
+        begin
+          SetLength(Result, Length(Result)+1);
+          Result[High(Result)].A := A;
+          Result[High(Result)].B := B;
+          Result[High(Result)].C := C;
+        end;
 
         tmp2[rshift+i]   := A;
         tmp2[rshift+i+1] := C;