Add settings related to max_endpoint_distance

Adds properties to determine in which direction the rope should be
constrained when exceeding max_endpoint_distance.

Author: mphe

demo/addons/ropesim/Rope.gd

@@ -30,6 +30,18 @@ signal on_point_count_changed()
 ## Fixed points in between are not taken into account.
 @export var max_endpoint_distance: float = -1
 
+## If [member Rope.max_endpoint_distance] is set, contract the rope towards the first point.
+## If [member Rope.resolve_to_end] is set as well or if neither is set, the rope gets contracted
+## towards the center.
+## [member Rope.fixate_begin] will always take precedence over this property.
+@export var resolve_to_begin: bool = false
+
+## If [member Rope.max_endpoint_distance] is set, contract the rope towards the last point.
+## If [member Rope.resolve_to_begin] is set as well or if neither is set, the rope gets contracted
+## towards the center.
+## [member Rope.fixate_begin] will always take precedence over this property.
+@export var resolve_to_end: bool = false
+
 ## (Optional) Allows to distribute the length of rope segment in a non-uniform manner.
 ## Useful when certain parts of the rope should be more detailed than the rest.
 ## For example, if it is known that most movement happens at the beginning of the rope, a curve with

demo/project.godot

@@ -11,7 +11,7 @@ config_version=5
 [application]
 
 config/name="ropesim example"
-config/features=PackedStringArray("4.2")
+config/features=PackedStringArray("4.3")
 config/icon="res://rope_examples/icon.svg"
 
 [debug]

demo/rope_examples/rope_properties.tscn

@@ -63,15 +63,15 @@ metadata/_edit_group_ = true
 [node name="RopeHandle" type="Marker2D" parent="Rope15"]
 position = Vector2(-106.181, 0)
 script = ExtResource("3_mb3ny")
+strength = 1.0
 rope_path = NodePath("..")
 rope_position = 0.0
-strength = 1.0
 
 [node name="RopeHandle2" type="Marker2D" parent="Rope15"]
 position = Vector2(93.8187, 0)
 script = ExtResource("3_mb3ny")
-rope_path = NodePath("..")
 strength = 1.0
+rope_path = NodePath("..")
 
 [node name="Rope16" type="Node2D" parent="."]
 position = Vector2(365, 1438)
@@ -85,15 +85,15 @@ metadata/_edit_group_ = true
 [node name="RopeHandle" type="Marker2D" parent="Rope16"]
 position = Vector2(-106.181, 0)
 script = ExtResource("3_mb3ny")
+strength = 1.0
 rope_path = NodePath("..")
 rope_position = 0.0
-strength = 1.0
 
 [node name="RopeHandle2" type="Marker2D" parent="Rope16"]
 position = Vector2(93.8187, 0)
 script = ExtResource("3_mb3ny")
-rope_path = NodePath("..")
 strength = 1.0
+rope_path = NodePath("..")
 
 [node name="Rope17" type="Node2D" parent="."]
 position = Vector2(583, 1438)
@@ -106,15 +106,15 @@ metadata/_edit_group_ = true
 [node name="RopeHandle" type="Marker2D" parent="Rope17"]
 position = Vector2(-106.181, 0)
 script = ExtResource("3_mb3ny")
+strength = 1.0
 rope_path = NodePath("..")
 rope_position = 0.0
-strength = 1.0
 
 [node name="RopeHandle2" type="Marker2D" parent="Rope17"]
 position = Vector2(93.819, 0)
 script = ExtResource("3_mb3ny")
-rope_path = NodePath("..")
 strength = 1.0
+rope_path = NodePath("..")
 
 [node name="Rope18" type="Node2D" parent="."]
 position = Vector2(807, 1438)
@@ -128,18 +128,18 @@ metadata/_edit_group_ = true
 [node name="RopeHandle" type="Marker2D" parent="Rope18"]
 position = Vector2(-106.181, 0)
 script = ExtResource("3_mb3ny")
+strength = 1.0
 rope_path = NodePath("..")
 rope_position = 0.0
-strength = 1.0
 
 [node name="RopeHandle2" type="Marker2D" parent="Rope18"]
 position = Vector2(93.819, 0)
 script = ExtResource("3_mb3ny")
-rope_path = NodePath("..")
 strength = 1.0
+rope_path = NodePath("..")
 
 [node name="Node2D2" type="Node2D" parent="."]
-position = Vector2(180.7, 124.476)
+position = Vector2(146.001, 146.237)
 
 [node name="Rope3" type="Node2D" parent="Node2D2"]
 position = Vector2(-88.3748, -22.2188)
@@ -414,13 +414,20 @@ text = "max_endpoint_distance provides an easy way to constraint the rope length
 
 [node name="Label22" type="Label" parent="."]
 offset_left = 1267.0
-offset_top = 1328.0
+offset_top = 1698.0
 offset_right = 2007.0
-offset_bottom = 1351.0
+offset_bottom = 1747.0
 text = "max_endpoint_distance only considers the distance between both endpoints.
 Does not consider the actual rope length.
 "
 
+[node name="Label28" type="Label" parent="."]
+offset_left = 1267.0
+offset_top = 1364.0
+offset_right = 2067.0
+offset_bottom = 1387.0
+text = "It can be specified how to contract the rope when exceeding max_endpoint_distance."
+
 [node name="Label20" type="Label" parent="."]
 offset_left = 1236.0
 offset_top = 956.0
@@ -460,7 +467,7 @@ theme_override_styles/separator = SubResource("StyleBoxFlat_f4u3w")
 offset_left = 1105.0
 offset_top = 854.0
 offset_right = 1309.0
-offset_bottom = 1771.0
+offset_bottom = 2129.0
 theme_override_styles/separator = SubResource("StyleBoxFlat_f4u3w")
 
 [node name="Rope" type="Node2D" parent="."]
@@ -470,8 +477,8 @@ script = ExtResource("4_rnvio")
 [node name="RopeHandle" type="Marker2D" parent="Rope"]
 position = Vector2(136, 257)
 script = ExtResource("3_mb3ny")
-rope_path = NodePath("..")
 strength = 1.0
+rope_path = NodePath("..")
 
 [node name="Rope2" type="Node2D" parent="."]
 position = Vector2(1697, 992)
@@ -481,54 +488,134 @@ max_endpoint_distance = 100.0
 [node name="RopeHandle" type="Marker2D" parent="Rope2"]
 position = Vector2(136, 257)
 script = ExtResource("3_mb3ny")
-rope_path = NodePath("..")
 strength = 1.0
+rope_path = NodePath("..")
 
 [node name="Label23" type="Label" parent="."]
 offset_left = 1236.0
-offset_top = 1406.0
+offset_top = 1776.0
 offset_right = 1460.0
-offset_bottom = 1429.0
+offset_bottom = 1799.0
 text = "max_endpoint_distance = -1"
 
+[node name="Label25" type="Label" parent="."]
+offset_left = 1651.0
+offset_top = 1497.0
+offset_right = 1875.0
+offset_bottom = 1520.0
+text = "resolve_to_begin = true"
+
+[node name="Label27" type="Label" parent="."]
+offset_left = 1650.0
+offset_top = 1422.0
+offset_right = 1874.0
+offset_bottom = 1445.0
+text = "default (center)"
+
+[node name="Label26" type="Label" parent="."]
+offset_left = 1649.0
+offset_top = 1563.0
+offset_right = 1873.0
+offset_bottom = 1586.0
+text = "resolve_to_end = true"
+
 [node name="Label24" type="Label" parent="."]
 offset_left = 1609.0
-offset_top = 1406.0
+offset_top = 1776.0
 offset_right = 1837.0
-offset_bottom = 1429.0
+offset_bottom = 1799.0
 text = "max_endpoint_distance = 100"
 
 [node name="Rope4" type="Node2D" parent="."]
-position = Vector2(1697, 1442)
+position = Vector2(1697, 1812)
 script = ExtResource("4_rnvio")
 max_endpoint_distance = 100.0
 
 [node name="RopeHandle" type="Marker2D" parent="Rope4"]
 position = Vector2(250, 56)
 script = ExtResource("3_mb3ny")
+strength = 1.0
 rope_path = NodePath("..")
 rope_position = 0.622
-strength = 1.0
 
 [node name="RopeHandle2" type="Marker2D" parent="Rope4"]
 position = Vector2(139, 249)
 script = ExtResource("3_mb3ny")
-rope_path = NodePath("..")
 strength = 1.0
+rope_path = NodePath("..")
 
 [node name="Rope5" type="Node2D" parent="."]
-position = Vector2(1318, 1446)
+position = Vector2(1318, 1816)
 script = ExtResource("4_rnvio")
 
 [node name="RopeHandle" type="Marker2D" parent="Rope5"]
 position = Vector2(250, 56)
 script = ExtResource("3_mb3ny")
+strength = 1.0
 rope_path = NodePath("..")
 rope_position = 0.622
-strength = 1.0
 
 [node name="RopeHandle2" type="Marker2D" parent="Rope5"]
 position = Vector2(139, 249)
 script = ExtResource("3_mb3ny")
+strength = 1.0
 rope_path = NodePath("..")
+
+[node name="Rope6" type="Node2D" parent="."]
+position = Vector2(1288, 1431)
+script = ExtResource("4_rnvio")
+max_endpoint_distance = 150.0
+resolve_to_begin = true
+fixate_begin = false
+
+[node name="RopeHandle" type="Marker2D" parent="Rope6"]
+position = Vector2(-7, 79)
+script = ExtResource("3_mb3ny")
+strength = 1.0
+rope_path = NodePath("..")
+rope_position = 0.0
+
+[node name="RopeHandle2" type="Marker2D" parent="Rope6"]
+position = Vector2(323, 78)
+script = ExtResource("3_mb3ny")
+strength = 1.0
+rope_path = NodePath("..")
+
+[node name="Rope8" type="Node2D" parent="."]
+position = Vector2(1288, 1336)
+script = ExtResource("4_rnvio")
+max_endpoint_distance = 150.0
+fixate_begin = false
+
+[node name="RopeHandle" type="Marker2D" parent="Rope8"]
+position = Vector2(-7, 99)
+script = ExtResource("3_mb3ny")
+strength = 1.0
+rope_path = NodePath("..")
+rope_position = 0.0
+
+[node name="RopeHandle2" type="Marker2D" parent="Rope8"]
+position = Vector2(323, 98)
+script = ExtResource("3_mb3ny")
+strength = 1.0
+rope_path = NodePath("..")
+
+[node name="Rope7" type="Node2D" parent="."]
+position = Vector2(1288, 1496)
+script = ExtResource("4_rnvio")
+max_endpoint_distance = 150.0
+resolve_to_end = true
+fixate_begin = false
+
+[node name="RopeHandle" type="Marker2D" parent="Rope7"]
+position = Vector2(-7, 83)
+script = ExtResource("3_mb3ny")
+strength = 1.0
+rope_path = NodePath("..")
+rope_position = 0.0
+
+[node name="RopeHandle2" type="Marker2D" parent="Rope7"]
+position = Vector2(323, 82)
+script = ExtResource("3_mb3ny")
 strength = 1.0
+rope_path = NodePath("..")

src/NativeRopeContext.cpp

@@ -44,6 +44,8 @@ void NativeRopeContext::load_context(Node2D* rope)
     seg_lengths = rope->call("get_segment_lengths");
     simulation_weights = rope->get("_simulation_weights");
     fixate_begin = rope->get("fixate_begin");
+    resolve_to_begin = rope->get("resolve_to_begin");
+    resolve_to_end = rope->get("resolve_to_end");
 }
 
 void NativeRopeContext::simulate(double delta)
@@ -173,29 +175,43 @@ static void constraint_segment(Vector2* point_a, Vector2* point_b, float weight_
 void NativeRopeContext::_constraint()
 {
     const bool use_euclid_constraint = max_endpoint_distance > 0;
-    Vector2* first_point;
-    Vector2* last_point;
-    float euclid_constraint_first_weight;
-    float max_stretch_length_sqr;
 
     if (use_euclid_constraint)
     {
-        first_point = &points[0];
-        last_point = &points[(int)points.size() - 1];
-        euclid_constraint_first_weight = fixate_begin ? 0.0 : 1.0;
-        max_stretch_length_sqr = max_endpoint_distance * max_endpoint_distance;
-    }
+        Vector2* const first_point = &points[0];
+        Vector2* const last_point = &points[(int)points.size() - 1];
+        const float max_stretch_length_sqr = max_endpoint_distance * max_endpoint_distance;
+        const float rope_length_sqr = first_point->distance_squared_to(*last_point);
 
-    for (int _ = 0; _ < num_constraint_iterations; ++_)
-    {
-        if (use_euclid_constraint)
+        if (rope_length_sqr > max_stretch_length_sqr)
         {
-            const float rope_length_sqr = first_point->distance_squared_to(*last_point);
-
-            if (rope_length_sqr > max_stretch_length_sqr)
-                constraint_segment(first_point, last_point, euclid_constraint_first_weight, 1.0, max_endpoint_distance);
+            float weight_a;
+            float weight_b;
+
+            // Always has priority
+            if (fixate_begin)
+            {
+                weight_a = 0.0;
+                weight_b = 1.0;
+            }
+            else if (resolve_to_begin == resolve_to_end)
+            {
+                weight_a = 1.0;
+                weight_b = 1.0;
+            }
+            else
+            {
+                weight_a = resolve_to_begin ? 0.0 : 1.0;
+                weight_b = resolve_to_end ? 0.0 : 1.0;
+            }
+
+            constraint_segment(first_point, last_point, weight_a, weight_b, max_endpoint_distance);
         }
+    }
+
 
+    for (int _ = 0; _ < num_constraint_iterations; ++_)
+    {
         for (int i = 0; i < points.size() - 1; ++i)
             constraint_segment(&points[i], &points[i + 1], simulation_weights[i], simulation_weights[i + 1], seg_lengths[i]);
     }

src/NativeRopeContext.hpp

@@ -37,6 +37,8 @@ namespace godot
             int num_constraint_iterations;
             Ref<Curve> damping_curve;
             bool fixate_begin;
+            bool resolve_to_begin;
+            bool resolve_to_end;
     };
 }