more mods

mods/automobiles_pck/automobiles_lib/custom_physics.lua

@@ -0,0 +1,95 @@
+function automobiles_lib.physics(self)
+    local friction = self._ground_friction or 0.99
+	local vel=self.object:get_velocity()
+    local new_velocity = vector.new()
+
+	--buoyancy
+	local surface = nil
+	local surfnodename = nil
+	local spos = automobiles_lib.get_stand_pos(self)
+    if not spos then return end
+	spos.y = spos.y+0.01
+	-- get surface height
+	local snodepos = automobiles_lib.get_node_pos(spos)
+	local surfnode = automobiles_lib.nodeatpos(spos)
+	while surfnode and (surfnode.drawtype == 'liquid' or surfnode.drawtype == 'flowingliquid') do
+		surfnodename = surfnode.name
+		surface = snodepos.y +0.5
+		if surface > spos.y+self.height then break end
+		snodepos.y = snodepos.y+1
+		surfnode = automobiles_lib.nodeatpos(snodepos)
+	end
+
+	self.isinliquid = surfnodename
+	if surface then				-- standing in liquid
+        self.isinliquid = true
+    end
+    local last_accel = vector.new()
+    if self._last_accel then
+        last_accel = vector.new(self._last_accel)
+    end
+
+    if self.isinliquid then
+        self.water_drag = 0.2
+        self.isinliquid = true
+        local height = self.height
+		local submergence = math.min(surface-spos.y,height)/height
+--		local balance = self.buoyancy*self.height
+        local buoyacc = automobiles_lib.gravity*(-1)*(self.buoyancy-submergence)
+        --local buoyacc = self._baloon_buoyancy*(self.buoyancy-submergence)
+        local accell = {
+                    x=-vel.x*self.water_drag,
+                    y=buoyacc-(vel.y*math.abs(vel.y)*0.4),
+                    z=-vel.z*self.water_drag
+                }
+        if self.buoyancy >= 1 then self._engine_running = false end
+        if last_accel then
+            accell = vector.add(accell,last_accel)
+        end
+        new_velocity = vector.multiply(accell,self.dtime)
+	else
+		self.isinliquid = false
+        new_velocity = vector.multiply(last_accel,self.dtime)
+	end
+
+    if self.isonground and not self.isinliquid then
+        --dumb friction
+        new_velocity = {x=new_velocity.x*friction,
+							    y=new_velocity.y,
+							    z=new_velocity.z*friction}
+        --core.chat_send_all(dump(friction))
+
+        -- bounciness
+        if self.springiness and self.springiness > 0 and self.buoyancy >= 1 then
+            local vnew = vector.new(new_velocity)
+
+            if not self.collided then						-- ugly workaround for inconsistent collisions
+	            for _,k in ipairs({'y','z','x'}) do
+		            if new_velocity[k]==0 and math.abs(self.lastvelocity[k])> 0.1 then
+			            vnew[k]=-self.lastvelocity[k]*self.springiness
+		            end
+	            end
+            end
+
+            if not vector.equals(new_velocity,vnew) then
+	            self.collided = true
+            else
+	            if self.collided then
+		            vnew = vector.new(self.lastvelocity)
+	            end
+	            self.collided = false
+            end
+            new_velocity = vnew
+        end
+
+        --fix bug with unexpected moving
+        if not self.driver_name and math.abs(vel.x) < 0.2 and math.abs(vel.z) < 0.2 then
+            self.object:set_velocity({x=0,y=automobiles_lib.gravity*(-1)*self.dtime,z=0})
+            if self.wheels then self.wheels:set_animation_frame_speed(0) end
+            return
+        end
+    end
+    
+    self.object:add_velocity(new_velocity)
+end
+