rigidbody: Add force field support

Force fields work with rigid bodies just like they do with other simulations.

Increase min and max strength of force fields so they can influence heavy rigid
bodies.

TODO: Adjust force field strength based on the time step taken.

Part of GSoC 2010 and 2012.
Authors: Joshua Leung (aligorith), Sergej Reich (sergof)

source/blender/blenkernel/intern/rigidbody.c

@@ -97,6 +97,10 @@ void BKE_rigidbody_free_world(RigidBodyWorld *rbw)
 	if (rbw->objects)
 		free(rbw->objects);
 
+	/* free effector weights */
+	if (rbw->effector_weights)
+		MEM_freeN(rbw->effector_weights);
+
 	/* free rigidbody world itself */
 	MEM_freeN(rbw);
 }
@@ -459,6 +463,8 @@ RigidBodyWorld *BKE_rigidbody_create_world(Scene *scene)
 	rbw = MEM_callocN(sizeof(RigidBodyWorld), "RigidBodyWorld");
 
 	/* set default settings */
+	rbw->effector_weights = BKE_add_effector_weights(NULL);
+
 	rbw->ltime = PSFRA;
 
 	rbw->time_scale = 1.0f;
@@ -596,6 +602,7 @@ static void rigidbody_update_sim_world(Scene *scene, RigidBodyWorld *rbw)
 	/* adjust gravity to take effector weights into account */
 	if (scene->physics_settings.flag & PHYS_GLOBAL_GRAVITY) {
 		copy_v3_v3(adj_gravity, scene->physics_settings.gravity);
+		mul_v3_fl(adj_gravity, rbw->effector_weights->global_gravity * rbw->effector_weights->weight[0]);
 	}
 	else {
 		zero_v3(adj_gravity);
@@ -631,6 +638,43 @@ static void rigidbody_update_sim_ob(Scene *scene, RigidBodyWorld *rbw, Object *o
 		RB_body_activate(rbo->physics_object);
 		RB_body_set_loc_rot(rbo->physics_object, loc, rot);
 	}
+	/* update influence of effectors - but don't do it on an effector */
+	/* only dynamic bodies need effector update */
+	else if (rbo->type == RBO_TYPE_ACTIVE && ((ob->pd == NULL) || (ob->pd->forcefield == PFIELD_NULL))) {
+		EffectorWeights *effector_weights = rbw->effector_weights;
+		EffectedPoint epoint;
+		ListBase *effectors;
+
+		/* get effectors present in the group specified by effector_weights */
+		effectors = pdInitEffectors(scene, ob, NULL, effector_weights);
+		if (effectors) {
+			float force[3] = {0.0f, 0.0f, 0.0f};
+			float loc[3], vel[3];
+
+			/* create dummy 'point' which represents last known position of object as result of sim */
+			// XXX: this can create some inaccuracies with sim position, but is probably better than using unsimulated vals?
+			RB_body_get_position(rbo->physics_object, loc);
+			RB_body_get_linear_velocity(rbo->physics_object, vel);
+
+			pd_point_from_loc(scene, loc, vel, 0, &epoint);
+
+			/* calculate net force of effectors, and apply to sim object
+			 *	- we use 'central force' since apply force requires a "relative position" which we don't have...
+			 */
+			pdDoEffectors(effectors, NULL, effector_weights, &epoint, force, NULL);
+			if (G.f & G_DEBUG)
+				printf("\tapplying force (%f,%f,%f) to '%s'\n", force[0], force[1], force[2], ob->id.name + 2);
+			/* activate object in case it is deactivated */
+			if (!is_zero_v3(force))
+				RB_body_activate(rbo->physics_object);
+			RB_body_apply_central_force(rbo->physics_object, force);
+		}
+		else if (G.f & G_DEBUG)
+			printf("\tno forces to apply to '%s'\n", ob->id.name + 2);
+
+		/* cleanup */
+		pdEndEffectors(&effectors);
+	}
 	/* NOTE: passive objects don't need to be updated since they don't move */
 
 	/* NOTE: no other settings need to be explicitly updated here,

source/blender/blenloader/intern/readfile.c

@@ -5021,6 +5021,8 @@ static void lib_link_scene(FileData *fd, Main *main)
 				RigidBodyWorld *rbw = sce->rigidbody_world;
 				if (rbw->group)
 					rbw->group = newlibadr(fd, sce->id.lib, rbw->group);
+				if (rbw->effector_weights)
+					rbw->effector_weights->group = newlibadr(fd, sce->id.lib, rbw->effector_weights->group);
 			}
 			
 			if (sce->nodetree) {
@@ -5296,6 +5298,11 @@ static void direct_link_scene(FileData *fd, Scene *sce)
 		rbw->physics_world = NULL;
 		rbw->objects = NULL;
 		rbw->numbodies = 0;
+
+		/* set effector weights */
+		rbw->effector_weights = newdataadr(fd, rbw->effector_weights);
+		if (!rbw->effector_weights)
+			rbw->effector_weights = BKE_add_effector_weights(NULL);
 	}
 }
 

source/blender/blenloader/intern/writefile.c

@@ -2306,6 +2306,7 @@ static void write_scenes(WriteData *wd, ListBase *scebase)
 		/* writing RigidBodyWorld data to the blend file */
 		if (sce->rigidbody_world) {
 			writestruct(wd, DATA, "RigidBodyWorld", 1, sce->rigidbody_world);
+			writestruct(wd, DATA, "EffectorWeights", 1, sce->rigidbody_world->effector_weights);
 		}
 		
 		sce= sce->id.next;

source/blender/makesdna/DNA_rigidbody_types.h

@@ -37,6 +37,8 @@
 
 struct Group;
 
+struct EffectorWeights;
+
 /* ******************************** */
 /* RigidBody World */
 
@@ -46,6 +48,8 @@ struct Group;
  */
 typedef struct RigidBodyWorld {
 	/* Sim World Settings ------------------------------------------------------------- */
+	struct EffectorWeights *effector_weights; /* effectors info */
+
 	struct Group *group;		/* Group containing objects to use for Rigid Bodies */
 	struct Object **objects;	/* Array to access group objects by index, only used at runtime */
 	

source/blender/makesrna/intern/rna_object_force.c

@@ -1182,7 +1182,7 @@ static void rna_def_field(BlenderRNA *brna)
 	
 	prop = RNA_def_property(srna, "strength", PROP_FLOAT, PROP_NONE);
 	RNA_def_property_float_sdna(prop, NULL, "f_strength");
-	RNA_def_property_range(prop, -1000.0f, 1000.0f);
+	RNA_def_property_range(prop, -FLT_MAX, FLT_MAX);
 	RNA_def_property_ui_text(prop, "Strength", "Strength of force field");
 	RNA_def_property_update(prop, 0, "rna_FieldSettings_update");
 

source/blender/makesrna/intern/rna_rigidbody.c

@@ -345,6 +345,12 @@ static void rna_def_rigidbody_world(BlenderRNA *brna)
 	RNA_def_property_boolean_funcs(prop, NULL, "rna_RigidBodyWorld_split_impulse_set");
 	RNA_def_property_ui_text(prop, "Split Impulse", "Reduces extra velocity that can build up when objects collide (lowers simulation stabilty a litte so use only when necessary)");
 	RNA_def_property_update(prop, NC_SCENE, "rna_RigidBodyWorld_reset");
+
+	/* effector weights */
+	prop = RNA_def_property(srna, "effector_weights", PROP_POINTER, PROP_NONE);
+	RNA_def_property_struct_type(prop, "EffectorWeights");
+	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+	RNA_def_property_ui_text(prop, "Effector Weights", "");
 }
 
 static void rna_def_rigidbody_object(BlenderRNA *brna)