EPhysics: soft body dragging support

This patch introduces an API to freeze(dragging_set) an specific
soft body trimesh face untill it gets called to unfreeze(dragging_unset) it.


Patch by: Leandro Dorileo <dorileo@profusion.mobi>



SVN revision: 78091

legacy/ephysics/src/bin/test_flag.c

@@ -35,12 +35,16 @@ _mouse_down_cb(void *data, Evas *e __UNUSED__, Evas_Object *obj, void *event_inf
   grabbing->click_data.y = mdown->output.y - y;
   grabbing->click_data.node = ephysics_body_soft_body_triangle_index_get(
                                grabbing->body, mdown->output.x, mdown->output.y);
+
+  ephysics_body_soft_body_dragging_set(grabbing->body,
+                                       grabbing->click_data.node);
 }
 
 static void
 _mouse_up_cb(void *data, Evas *e __UNUSED__, Evas_Object *obj __UNUSED__, void *event_info __UNUSED__)
 {
   Grabbing_Data *grabbing = data;
+  ephysics_body_soft_body_dragging_unset(grabbing->body);
   grabbing->mouse_status = 0;
 }
 

legacy/ephysics/src/lib/EPhysics.h

@@ -1762,6 +1762,44 @@ EAPI void ephysics_body_soft_body_hardness_set(EPhysics_Body *body, double hardn
  */
 EAPI double ephysics_body_soft_body_hardness_get(const EPhysics_Body *body);
 
+/**
+ * @brief
+ * Set the soft body dragging status.
+ *
+ * While dragging a soft body the user may want to freeze a specific trimesh
+ * face, after calling this function EPhysics will do freeze the @p triangle
+ * untill it gets a call to unset it with
+ * ephysics_body_soft_body_dragging_unset().
+ *
+ * @note Freezing a specific trimesh face means no forces are applied to it, no
+ * gravity enforced, that's @p triangle will have no mass untill it dragging gets
+ * unset.
+ *
+ * @param body The body of interest.
+ * @param triangle The triangle to freeze.
+ *
+ * @see ephysics_body_soft_body_dragging_unset().
+ * @see ephysics_body_soft_body_triangle_index_get().
+ *
+ * @ingroup EPhysics_Body
+ */
+EAPI void ephysics_body_soft_body_dragging_set(EPhysics_Body *body, int triangle);
+
+/**
+ * @brief
+ * Unset the soft body dragging status.
+ *
+ * This function will tell EPhysics to not freeze - the previously dragging
+ * triangle set - any more.
+ *
+ * @param body The body to unset the dragging status.
+ *
+ * @see ephysics_body_soft_body_dragging_set() for dragging details.
+ *
+ * @ingroup EPhysics_Body
+ */
+EAPI void ephysics_body_soft_body_dragging_unset(EPhysics_Body *body);
+
 /**
  * @brief
  * Get the triangle index of a soft body in @p x and @p y.

legacy/ephysics/src/lib/ephysics_body.cpp

@@ -780,6 +780,23 @@ _ephysics_body_volume_get(const EPhysics_Body *body)
    return vector.x() * vector.y() * vector.z();
 }
 
+void
+_ephysics_body_soft_body_dragging_set(EPhysics_Body *body, int triangle)
+{
+   btSoftBody::Face face;
+   btSoftBody::Node *node;
+
+   body->dragging_data.triangle = triangle;
+   body->dragging_data.dragging = EINA_TRUE;
+
+   face = body->soft_body->m_faces[triangle];
+   for (int i = 0; i < 3; i++)
+     {
+        node = face.m_n[i];
+        body->dragging_data.mass[i] = node->m_im;
+     }
+}
+
 static void
 _ephysics_body_mass_set(EPhysics_Body *body, double mass)
 {
@@ -789,7 +806,12 @@ _ephysics_body_mass_set(EPhysics_Body *body, double mass)
      mass = body->density * _ephysics_body_volume_get(body);
 
    if (body->soft_body)
-     body->soft_body->setTotalMass(mass);
+     {
+        body->soft_body->setTotalMass(mass);
+        if (body->dragging_data.dragging)
+          _ephysics_body_soft_body_dragging_set(body,
+                                                body->dragging_data.triangle);
+     }
    else
      {
         body->collision_shape->calculateLocalInertia(mass, inertia);
@@ -1232,6 +1254,68 @@ ephysics_body_soft_body_hardness_set(EPhysics_Body *body, double hardness)
    ephysics_world_lock_release(body->world);
 }
 
+EAPI void
+ephysics_body_soft_body_dragging_set(EPhysics_Body *body, int triangle)
+{
+   if (!body)
+     {
+        ERR("Can't set soft body dragging status, body is null.");
+        return;
+     }
+
+   if (body->type == EPHYSICS_BODY_TYPE_RIGID)
+     {
+        ERR("Can set soft body dragging status, body must not be a rigid body.");
+        return;
+     }
+
+   if (triangle < 0 || triangle >= body->soft_body->m_faces.size())
+     {
+        ERR("Could not move soft body triangle, provided body triangle index "
+            "ranges from 0 to %d", body->soft_body->m_faces.size());
+        return;
+     }
+
+   ephysics_world_lock_take(body->world);
+   _ephysics_body_soft_body_dragging_set(body, triangle);
+   ephysics_world_lock_release(body->world);
+
+   DBG("Body %p appended to world's dragging bodies list.", body);
+}
+
+EAPI void
+ephysics_body_soft_body_dragging_unset(EPhysics_Body *body)
+{
+   btSoftBody::Face face;
+   btSoftBody::Node *node;
+
+   if (!body)
+     {
+        ERR("Can't unset soft body dragging status, body is null.");
+        return;
+     }
+
+   if (body->type == EPHYSICS_BODY_TYPE_RIGID)
+     {
+        ERR("Can unset soft body dragging status, body must not be a rigid"
+            " body.");
+        return;
+     }
+
+   ephysics_world_lock_take(body->world);
+   face = body->soft_body->m_faces[body->dragging_data.triangle];
+   for (int i = 0; i < 3; i++)
+     {
+        node = face.m_n[i];
+        node->m_im = body->dragging_data.mass[i];
+        body->dragging_data.mass[i] = 0;
+     }
+
+   body->dragging_data.dragging = EINA_FALSE;
+   body->dragging_data.triangle = 0;
+   ephysics_world_lock_release(body->world);
+}
+
 EAPI double
 ephysics_body_soft_body_hardness_get(const EPhysics_Body *body)
 {
@@ -1448,7 +1532,7 @@ no_body:
 }
 
 static void
-_ephysics_body_soft_body_single_face_transform(btSoftBody *soft_body, int face_idx, int node_idx, btTransform trans, btScalar vel_reduction)
+_ephysics_body_soft_body_single_face_transform(btSoftBody *soft_body, int face_idx, int node_idx, btTransform trans)
 {
    btSoftBody::Node *node;
    ATTRIBUTE_ALIGNED16(btDbvtVolume) vol;
@@ -1458,11 +1542,25 @@ _ephysics_body_soft_body_single_face_transform(btSoftBody *soft_body, int face_i
    node->m_x = trans * node->m_x;
    node->m_q = trans * node->m_q;
    node->m_n = trans.getBasis() * node->m_n;
-   node->m_v *= vel_reduction;
    vol = btDbvtVolume::FromCR(node->m_x, margin);
    soft_body->m_ndbvt.update(node->m_leaf, vol);
 }
 
+void
+ephysics_body_soft_body_dragging_apply(EPhysics_Body *body)
+{
+   btSoftBody::Face face;
+   btSoftBody::Node *node;
+
+   face = body->soft_body->m_faces[body->dragging_data.triangle];
+   for (int i = 0; i < 3; i++)
+     {
+        node = face.m_n[i];
+        node->m_v *= 0;
+	node->m_im *= 0;
+     }
+}
+
 EAPI void
 ephysics_body_soft_body_triangle_move(EPhysics_Body *body, int idx, Evas_Coord x, Evas_Coord y, Evas_Coord z)
 {
@@ -1505,7 +1603,7 @@ ephysics_body_soft_body_triangle_move(EPhysics_Body *body, int idx, Evas_Coord x
         diff.setIdentity();
         diff.setOrigin(new_pos - node->m_x);
         _ephysics_body_soft_body_single_face_transform(body->soft_body, idx, i,
-                                                       diff, 0.25);
+                                                       diff);
 
         if (!i) continue;
 
@@ -1514,7 +1612,7 @@ ephysics_body_soft_body_triangle_move(EPhysics_Body *body, int idx, Evas_Coord x
           {
              if (m == idx) continue;
              _ephysics_body_soft_body_single_face_transform(body->soft_body, m,
-                                                            i, diff, 0.05);
+                                                            i, diff);
           }
      }
 

legacy/ephysics/src/lib/ephysics_private.h

@@ -117,6 +117,11 @@ struct _EPhysics_Body {
      Eina_Bool light_apply:1;
      int material_index;
      Eina_Bool rebounding;
+     struct {
+       int triangle;
+       double mass[3];
+       Eina_Bool dragging;
+     } dragging_data;
 };
 
 extern int _ephysics_log_dom;
@@ -153,6 +158,7 @@ void ephysics_body_recalc(EPhysics_Body *body, double rate);
 void ephysics_body_forces_apply(EPhysics_Body *body);
 void ephysics_body_activate(const EPhysics_Body *body, Eina_Bool activate);
 void ephysics_body_evas_objects_restack(EPhysics_World *world);
+void ephysics_body_soft_body_dragging_apply(EPhysics_Body *body);
 
 /* Camera */
 EPhysics_Camera *ephysics_camera_add(EPhysics_World *world);

legacy/ephysics/src/lib/ephysics_world.cpp

@@ -589,7 +589,11 @@ _th_simulate(void *data, Ecore_Thread *th)
         world->cur_th = th;
 
         EINA_INLIST_FOREACH(world->bodies, body)
-           ephysics_body_forces_apply(body);
+          {
+             ephysics_body_forces_apply(body);
+             if (body->dragging_data.dragging)
+               ephysics_body_soft_body_dragging_apply(body);
+          }
 
         time_now = ecore_time_get();
         delta = time_now - world->last_update;