Add anchor constraint and use it to lock center point in dock model.

3 files changed, 46 insertions, 28 deletions

diff --git a/akamaru.c b/akamaru.c
index ae01a27..8045454 100644
--- a/akamaru.c
+++ b/akamaru.c
@@ -77,6 +77,14 @@ spacer_init (Spacer *spacer, Object *a, Object *b, double length)
 }
 
 void
+anchor_init (Anchor *anchor, Object *object, double x, double y)
+{
+  anchor->object = object;
+  anchor->x = x;
+  anchor->y = y;
+}
+
+void
 polygon_init (Polygon *p, int num_points, ...)
 {
   double dx, dy, length;
@@ -317,6 +325,15 @@ model_constrain_polygon (Model *model, Polygon *polygon)
 }
 
 static void
+model_constrain_anchor (Model *model, Anchor *anchor)
+{
+  anchor->object->position.x = anchor->x;
+  anchor->object->position.y = anchor->y;
+  anchor->object->previous_position.x = anchor->x;
+  anchor->object->previous_position.y = anchor->y;
+}
+
+static void
 model_constrain_offset (Model *model, Offset *offset)
 {
   double x, y;
@@ -344,13 +361,10 @@ model_constrain (Model *model)
   double dx, dy, x, y, distance, fraction;
   int i;
 
-  /* Anchor object constraint. */
-  if (model->anchor_object != NULL) {
-    model->anchor_object->position.x = model->anchor_position.x;
-    model->anchor_object->position.y = model->anchor_position.y;
-    model->anchor_object->previous_position.x = model->anchor_position.x;
-    model->anchor_object->previous_position.y = model->anchor_position.y;
-  }
+  if (model->mouse_anchor.object != NULL)
+    model_constrain_anchor (model, &model->mouse_anchor);
+  for (i = 0; i < model->num_anchors; i++)
+    model_constrain_anchor (model, &model->anchors[i]);
 
   /* String constraints. */
   for (i = 0; i < model->num_strings; i++) {
diff --git a/akamaru.h b/akamaru.h
index 1646a34..cf7bf8b 100644
--- a/akamaru.h
+++ b/akamaru.h
@@ -13,6 +13,7 @@ typedef struct _String String;
 typedef struct _Spring Spring;
 typedef struct _OffsetSpring OffsetSpring;
 typedef struct _Spacer Spacer;
+typedef struct _Anchor Anchor;
 typedef struct _Polygon Polygon;
 typedef struct _Offset Offset;
 typedef struct _Model Model;
@@ -59,6 +60,11 @@ struct _Spacer {
   int length;
 };
 
+struct _Anchor {
+  Object *object;
+  double x, y;
+};
+
 struct _Polygon {
   int num_points;
   Point *points;
@@ -81,13 +87,14 @@ struct _Model {
   OffsetSpring *offset_springs;
   int num_spacers;
   Spacer *spacers;
+  int num_anchors;
+  Anchor *anchors;
   int num_polygons;
   Polygon *polygons;
   double k;
   double friction;
 
-  Object *anchor_object;
-  Vector anchor_position;
+  Anchor mouse_anchor;
 
   double theta;
 };
@@ -99,6 +106,7 @@ void spring_init (Spring *spring, Object *a, Object *b, double length);
 void stick_init (Stick *stick, Object *a, Object *b, double length);
 void string_init (String *string, Object *a, Object *b, double length);
 void spacer_init (Spacer *spacer, Object *a, Object *b, double length);
+void anchor_init (Anchor *anchor, Object *object, double x, double y);
 
 void polygon_init (Polygon *p, int num_points, ...);
 void polygon_init_diamond (Polygon *polygon, double x, double y);
diff --git a/main.c b/main.c
index 39cb5ad..3b1d8d4 100644
--- a/main.c
+++ b/main.c
@@ -63,8 +63,6 @@ model_init_snake (Model *model)
       model->sticks[i * 2 + 1].length = random() % 20 + 20;
     }
   }
-
-  model->anchor_object = NULL;
 }
 
 static void
@@ -91,8 +89,6 @@ model_init_rope (Model *model)
       model->sticks[i].length = stick_length;
     }
   }
-
-  model->anchor_object = NULL;
 }
 
 static void
@@ -138,15 +134,13 @@ model_init_curtain (Model *model)
 
     model->offsets[0].objects[i] = &model->objects[i * num_rope_objects];
   }
-
-  model->anchor_object = NULL;
 }
 
 static void
 model_init_grid (Model *model)
 {
-  const int num_ropes = 4;
-  const int num_rope_objects = 4;
+  const int num_ropes = 8;
+  const int num_rope_objects = 8;
   const int num_objects = num_ropes * num_rope_objects;
   const int num_strings = num_ropes * (num_rope_objects - 1) +
     (num_ropes - 1) * num_rope_objects;
@@ -186,8 +180,6 @@ model_init_grid (Model *model)
 
     model->offsets[0].objects[i] = &model->objects[i * num_rope_objects];
   }
-
-  model->anchor_object = NULL;
 }
 
 static void
@@ -281,13 +273,17 @@ model_init_dock (Model *model)
   model->num_springs = num_springs;
   model->spacers = g_new (Spacer, num_spacers);
   model->num_spacers = num_spacers;
+  model->anchors = g_new (Anchor, 1);
+  model->num_anchors = 1;
   model->k = 0.1;
 
-  model_init_polygons (model);
   model->polygons = g_new (Polygon, 1);
-  polygon_init_rectangle (&model->polygons[0], -400, 300, 1400, 350);
   model->num_polygons = 1;
+  polygon_init_rectangle (&model->polygons[0], -400, 300, 1400, 350);
 
+  model->anchors[0].x = 300;
+  model->anchors[0].y = 300;
+  model->anchors[0].object = &model->objects[0];
 
   object = model->objects;
   spring = model->springs;
@@ -528,10 +524,10 @@ button_press_event (GtkWidget	   *widget,
   if (event->button != 1)
     return TRUE;
 
-  closure->model->anchor_position.x = event->x;
-  closure->model->anchor_position.y = event->y;
-  closure->model->anchor_object = model_find_nearest (closure->model,
-						      event->x, event->y);
+  closure->model->mouse_anchor.x = event->x;
+  closure->model->mouse_anchor.y = event->y;
+  closure->model->mouse_anchor.object =
+    model_find_nearest (closure->model, event->x, event->y);
 
   return TRUE;
 }
@@ -546,7 +542,7 @@ button_release_event (GtkWidget	     *widget,
   if ((event->state & GDK_BUTTON1_MASK) == 0)
     return TRUE;
 
-  closure->model->anchor_object = NULL;
+  closure->model->mouse_anchor.object = NULL;
 
   return TRUE;
 }
@@ -562,8 +558,8 @@ motion_notify_event (GtkWidget	    *widget,
 
   gdk_window_get_pointer (event->window, &x, &y, &state);
   
-  closure->model->anchor_position.x = x + 0.5;
-  closure->model->anchor_position.y = y + 0.5;
+  closure->model->mouse_anchor.x = x + 0.5;
+  closure->model->mouse_anchor.y = y + 0.5;
 
   return TRUE;
 }