Merge pull request #20861 from RandomShaper/improve-bitmap

Improve BitMap: expose methods + prevent stack overflow

scene/resources/bit_mask.cpp

@@ -418,10 +418,41 @@ static Vector<Vector2> reduce(const Vector<Vector2> &points, const Rect2i &rect,
 	return result;
 }
 
+struct FillBitsStackEntry {
+	Point2i pos;
+	int i;
+	int j;
+};
+
 static void fill_bits(const BitMap *p_src, Ref<BitMap> &p_map, const Point2i &p_pos, const Rect2i &rect) {
 
-	for (int i = p_pos.x - 1; i <= p_pos.x + 1; i++) {
+	// Using a custom stack to work iteratively to avoid stack overflow on big bitmaps
-		for (int j = p_pos.y - 1; j <= p_pos.y + 1; j++) {
+	PoolVector<FillBitsStackEntry> stack;
+	// Tracking size since we won't be shrinking the stack vector
+	int stack_size = 0;
+
+	Point2i pos = p_pos;
+	int next_i;
+	int next_j;
+
+	bool reenter = true;
+	bool popped = false;
+	do {
+		if (reenter) {
+			next_i = pos.x - 1;
+			next_j = pos.y - 1;
+			reenter = false;
+		}
+
+		for (int i = next_i; i <= pos.x + 1; i++) {
+			for (int j = next_j; j <= pos.y + 1; j++) {
+				if (popped) {
+					// The next loop over j must start normally
+					next_j = pos.y;
+					popped = false;
+					// Skip because an iteration was already executed with current counter values
+					continue;
+				}
 
 				if (i < rect.position.x || i >= rect.position.x + rect.size.x)
 					continue;
@@ -433,16 +464,45 @@ static void fill_bits(const BitMap *p_src, Ref<BitMap> &p_map, const Point2i &p_
 
 				else if (p_src->get_bit(Vector2(i, j))) {
 					p_map->set_bit(Vector2(i, j), true);
-				fill_bits(p_src, p_map, Point2i(i, j), rect);
+
+					FillBitsStackEntry se = { pos, i, j };
+					stack.resize(MAX(stack_size + 1, stack.size()));
+					stack.set(stack_size, se);
+					stack_size++;
+
+					pos = Point2i(i, j);
+					reenter = true;
+					break;
 				}
 			}
+			if (reenter) {
+				break;
 			}
+		}
+		if (!reenter) {
+			if (stack_size) {
+				FillBitsStackEntry se = stack.get(stack_size - 1);
+				stack_size--;
+				pos = se.pos;
+				next_i = se.i;
+				next_j = se.j;
+				popped = true;
+			}
+		}
+	} while (reenter || popped);
+
+#ifdef DEBUG_ENABLED
+	print_line("max stack size: " + itos(stack.size()));
+#endif
 }
+
 Vector<Vector<Vector2> > BitMap::clip_opaque_to_polygons(const Rect2 &p_rect, float p_epsilon) const {
 
 	Rect2i r = Rect2i(0, 0, width, height).clip(p_rect);
 
+#ifdef DEBUG_ENABLED
 	print_line("Rect: " + r);
+#endif
 	Point2i from;
 	Ref<BitMap> fill;
 	fill.instance();
@@ -454,9 +514,13 @@ Vector<Vector<Vector2> > BitMap::clip_opaque_to_polygons(const Rect2 &p_rect, fl
 			if (!fill->get_bit(Point2(j, i)) && get_bit(Point2(j, i))) {
 
 				Vector<Vector2> polygon = _march_square(r, Point2i(j, i));
+#ifdef DEBUG_ENABLED
 				print_line("pre reduce: " + itos(polygon.size()));
+#endif
 				polygon = reduce(polygon, r, p_epsilon);
+#ifdef DEBUG_ENABLED
 				print_line("post reduce: " + itos(polygon.size()));
+#endif
 				polygons.push_back(polygon);
 				fill_bits(this, fill, Point2i(j, i), r);
 			}
@@ -510,6 +574,34 @@ void BitMap::grow_mask(int p_pixels, const Rect2 &p_rect) {
 	}
 }
 
+Array BitMap::_opaque_to_polygons_bind(const Rect2 &p_rect, float p_epsilon) const {
+
+	Vector<Vector<Vector2> > result = clip_opaque_to_polygons(p_rect, p_epsilon);
+
+	// Convert result to bindable types
+
+	Array result_array;
+	result_array.resize(result.size());
+	for (int i = 0; i < result.size(); i++) {
+
+		const Vector<Vector2> &polygon = result[i];
+
+		PoolVector2Array polygon_array;
+		polygon_array.resize(polygon.size());
+
+		{
+			PoolVector2Array::Write w = polygon_array.write();
+			for (int j = 0; j < polygon.size(); j++) {
+				w[j] = polygon[j];
+			}
+		}
+
+		result_array[i] = polygon_array;
+	}
+
+	return result_array;
+}
+
 void BitMap::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("create", "size"), &BitMap::create);
@@ -526,6 +618,9 @@ void BitMap::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("_set_data"), &BitMap::_set_data);
 	ClassDB::bind_method(D_METHOD("_get_data"), &BitMap::_get_data);
 
+	ClassDB::bind_method(D_METHOD("grow_mask", "pixels", "rect"), &BitMap::grow_mask);
+	ClassDB::bind_method(D_METHOD("opaque_to_polygons", "rect", "epsilon"), &BitMap::_opaque_to_polygons_bind, DEFVAL(2.0));
+
 	ADD_PROPERTY(PropertyInfo(Variant::DICTIONARY, "data", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NOEDITOR | PROPERTY_USAGE_INTERNAL), "_set_data", "_get_data");
 }
 

scene/resources/bit_mask.h

@@ -46,6 +46,8 @@ class BitMap : public Resource {
 
 	Vector<Vector2> _march_square(const Rect2i &rect, const Point2i &start) const;
 
+	Array _opaque_to_polygons_bind(const Rect2 &p_rect, float p_epsilon) const;
+
 protected:
 	void _set_data(const Dictionary &p_d);
 	Dictionary _get_data() const;