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

[akamaru] / akamaru.c

diff --git a/akamaru.c b/akamaru.c
index d158f3e2da5b3728882025fb3ce9c3598def2aef..804545411e5c4227f2e5a0e6982fe3d3cd5d2a1d 100644 (file)
--- a/akamaru.c
+++ b/akamaru.c
@@ -42,6 +42,22 @@ spring_init (Spring *spring, Object *a, Object *b, double length)
   spring->length = length;
 }
 
+void
+stick_init (Stick *stick, Object *a, Object *b, double length)
+{
+  stick->a = a;
+  stick->b = b;
+  stick->length = length;
+}
+
+void
+string_init (String *string, Object *a, Object *b, double length)
+{
+  string->a = a;
+  string->b = b;
+  string->length = length;
+}
+
 void
 offset_spring_init (OffsetSpring *spring, Object *a, Object *b,
                    double dx, double dy)
@@ -52,6 +68,22 @@ offset_spring_init (OffsetSpring *spring, Object *a, Object *b,
   spring->dy = dy;
 }
 
+void
+spacer_init (Spacer *spacer, Object *a, Object *b, double length)
+{
+  spacer->a = a;
+  spacer->b = b;
+  spacer->length = 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, ...)
 {
@@ -75,7 +107,7 @@ polygon_init (Polygon *p, int num_points, ...)
   p->normals = g_new (Vector, p->num_points);
   /* Compute outward pointing normals.  p->normals[i] is the normal
    * for the edged between p->points[i] and p->points[i + 1]. */
- for (i = 0; i < p->num_points; i++) {
+  for (i = 0; i < p->num_points; i++) {
     j = (i + 1) % p->num_points;
     dx = p->points[j].x - p->points[i].x;
     dy = p->points[j].y - p->points[i].y;
@@ -115,6 +147,7 @@ model_fini (Model *model)
     g_free (model->offsets[i].objects);
   g_free (model->springs);
   g_free (model->offset_springs);
+  g_free (model->spacers);
   for (i = 0; i < model->num_polygons; i++)
     g_free (model->polygons[i].points);
   g_free (model->polygons);
@@ -291,6 +324,15 @@ 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)
 {
@@ -319,13 +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++) {
@@ -343,6 +382,22 @@ model_constrain (Model *model)
     model->strings[i].b->position.y = y + dy * (1 - fraction);
   }
 
+  /* Spacer constraints. */
+  for (i = 0; i < model->num_spacers; i++) {
+    x = model->spacers[i].a->position.x;
+    y = model->spacers[i].a->position.y;
+    dx = model->spacers[i].b->position.x - x;
+    dy = model->spacers[i].b->position.y - y;
+    distance = estimate_distance (dx, dy, model->spacers[i].length);
+    if (distance > model->spacers[i].length)
+      continue;
+    fraction = (distance - model->spacers[i].length) / distance / 2;
+    model->spacers[i].a->position.x = x + dx * fraction;
+    model->spacers[i].a->position.y = y + dy * fraction;
+    model->spacers[i].b->position.x = x + dx * (1 - fraction);
+    model->spacers[i].b->position.y = y + dy * (1 - fraction);
+  }
+
   /* Stick constraints. */
   for (i = 0; i < model->num_sticks; i++) {
     x = model->sticks[i].a->position.x;
@@ -373,7 +428,7 @@ model_step (Model *model, double delta_t)
 
   model_accumulate_forces (model);
   model_integrate (model, delta_t);
-  for (i = 0; i < 50; i++)
+  for (i = 0; i < 2; i++)
     model_constrain (model);
 
   model->theta += delta_t;