Move along players by teleporting

contraption.lua

@@ -25,7 +25,6 @@ local id_counter = 0
 -- Table containing the currently active contraptions keyed by their id.
 local active_contraptions = {}
 
--- TODO: Push along players.
 -- TODO: Friction depending on ground.
 -- TODO: Gravity.
 -- TODO: Water physics!
@@ -200,8 +199,11 @@ function contraption.load_from_string(id, str)
     local result = setmetatable({
         id = id,
 
-        region    = obj.region,
-        nodes     = obj.nodes,
+        region = {
+            min = vector.convert(obj.region.min),
+            max = vector.convert(obj.region.max)
+        },
+        nodes = obj.nodes,
         num_nodes = obj.num_nodes,
 
         motion  = obj.motion  and vector.convert(obj.motion ) or nil,
@@ -272,10 +274,24 @@ function contraption:update(delta_time)
     end
     -- .. and move it 1 step into that direction.
     if which ~= 0 then
+        local objects_to_move = {}
+        local pos1 = self.region.min:offset(-1, -1, -1)
+        local pos2 = self.region.max:offset( 1,  2,  1)
+        for _, obj in ipairs(minetest.get_objects_in_area(pos1, pos2)) do
+            if obj:is_player() then
+                local adjusted_pos = vector.offset(obj:get_pos(), 0, -0.5, 0)
+                local rel_pos = adjusted_pos:round() - self.region.min
+                if self.nodes[rel_pos:hash()] then
+                    table_insert(objects_to_move, obj)
+                end
+            end
+        end
+
         local step = vector.zero()
         step[which] = math.sign(self.partial[which])
         if self:move(step) then
             self.partial = self.partial - step
+            for _, obj in ipairs(objects_to_move) do obj:set_pos(vector.add(obj:get_pos(), step)) end
         else
             -- Reset motion into the direction that we bumped into.
             -- Allows for "sliding" along walls instead of stopping outright.