Slippery nodes

Updated and improved 'slippery' factor in a new groups setting(I'd
prefer to have a new property, but that'd require a new protocol, which
may not be wished?  Suggestions?).

Modified from: Zeg9's: minetest#817

src/client.cpp

@@ -464,7 +464,7 @@ void Client::step(float dtime)
 	// Control local player (0ms)
 	LocalPlayer *player = m_env.getLocalPlayer();
 	assert(player != NULL);
-	player->applyControl(dtime);
+	player->applyControl(dtime, &m_env);
 
 	// Step environment
 	m_env.step(dtime);

src/localplayer.cpp

@@ -398,7 +398,7 @@ void LocalPlayer::move(f32 dtime, Environment *env, f32 pos_max_d)
 	move(dtime, env, pos_max_d, NULL);
 }
 
-void LocalPlayer::applyControl(float dtime)
+void LocalPlayer::applyControl(float dtime, Environment *env)
 {
 	// Clear stuff
 	swimming_vertical = false;
@@ -611,7 +611,17 @@ void LocalPlayer::applyControl(float dtime)
 		incH = incV = movement_acceleration_default * BS * dtime;
 
 	// Accelerate to target speed with maximum increment
-	accelerateHorizontal(speedH * physics_override_speed, incH * physics_override_speed);
+	INodeDefManager *nodemgr = m_gamedef->ndef();
+	Map *map = &env->getMap();
+	v3s16 p = floatToInt(getPosition() - v3f(0,BS/2,0), BS);
+	ContentFeatures node = nodemgr->get(map->getNodeNoEx(p));
+	int slippery = itemgroup_get(node.groups, "slippery");
+	if (slippery==0 && (node.name=="air" || itemgroup_get(node.groups, "liquid")) && !free_move && !is_climbing && !control.sneak)
+	{
+		slippery = 10;
+	}
+
+	accelerateHorizontal(speedH * physics_override_speed, incH * physics_override_speed, slippery);
 	accelerateVertical(speedV * physics_override_speed, incV * physics_override_speed);
 }
 

src/localplayer.h

@@ -50,7 +50,7 @@ public:
 	void move(f32 dtime, Environment *env, f32 pos_max_d,
 			std::vector<CollisionInfo> *collision_info);
 
-	void applyControl(float dtime);
+	void applyControl(float dtime, Environment *env);
 
 	v3s16 getStandingNodePos();
 

src/player.cpp

@@ -112,12 +112,19 @@ Player::~Player()
 }
 
 // Horizontal acceleration (X and Z), Y direction is ignored
-void Player::accelerateHorizontal(v3f target_speed, f32 max_increase)
+void Player::accelerateHorizontal(v3f target_speed, f32 max_increase, int slippery)
 {
 	if(max_increase == 0)
 		return;
 
 	v3f d_wanted = target_speed - m_speed;
+	if (slippery)
+	{
+		if (target_speed == v3f(0))
+			d_wanted = -m_speed*.5/slippery;
+		else
+			d_wanted = target_speed*.1 - m_speed*.1;
+	}
 	d_wanted.Y = 0;
 	f32 dl = d_wanted.getLength();
 	if(dl > max_increase)

src/player.h

@@ -119,7 +119,7 @@ public:
 		m_speed = speed;
 	}
 
-	void accelerateHorizontal(v3f target_speed, f32 max_increase);
+	void accelerateHorizontal(v3f target_speed, f32 max_increase, int slippery);
 	void accelerateVertical(v3f target_speed, f32 max_increase);
 
 	v3f getPosition()