First version of API for changable nodes.

mods/default/changeable.lua

@@ -0,0 +1,103 @@
+
+--
+-- Changeable nodes
+--
+
+-- used for register named node changes to central control of action, like stone degradation by fall, flora etc.
+-- this changes are not happening automaticly, they have to be caused
+-- benefit is that causer don't have to know what he have to do with every node, he can only cause named change, 
+-- and change efect can be configuret in other place
+
+default.registered_changeable_nodes = {};
+default.register_changeable_nodes_by_change_names = {};
+
+-- change definition
+--
+-- new_node_name -> new name of node
+-- check_stability -> true, when stability should be rechecked after node change
+-- allow_change -> callback, can be nil, return true when change should happen
+--              -> parameters pos, node
+
+function default.register_changeable_node_change(node_name, change_name, change_def)
+  
+  if (type(change_def)~="table") then
+    minetest.log("warning", "Cannot register changeable node "..node_name.." change "..change_name.." without change definition.");
+    return
+  end
+  
+  if (type(change_def.new_node_name)~="string") then
+    minetest.log("warning", "Cannot register changeable node "..node_name.." change "..change_name.." with missing new_node_name string in change definition.");
+    return
+  end
+  
+  if (type(change_def.check_stability)~="boolean") then
+    minetest.log("warning", "Cannot register changeable node "..node_name.." change "..change_name.." with missing check_stability boolean in change definition.");
+    return
+  end
+  
+  if ((type(change_def.allow_change)~="nil")&&(type(change_def.allow_change)~="function")) then
+    minetest.log("warning", "Cannot register changeable node "..node_name.." change "..change_name.." with missing allow_change function in change definition.");
+    return
+  end
+  
+  changable_node = default.registered_changeable_nodes[node_name];
+  if (changable_node==nil) then
+    default.registered_changeable_nodes[node_name] = {changes = {}};
+    changable_node = default.registered_changeable_nodes[node_name];
+  end
+  
+  changable_node.changes[change_name] = change_def;
+  
+  table.insert(register_changeable_nodes_by_change_names[change_name], node_name);
+  
+  if (minetest.registered_nodes[node_name]~=nil) then
+    minetest.log("error", "Changeable source node name "..node_name.." is not valid registered node name. ( for change \""..change_name..""\")")
+  end
+  if (minetest.registered_nodes[change_def.new_node_name]~=nil) then
+    minetest.log("error", "Changeable target node name "..change_def.new_node_name.." is not valid registered node name. ( for change \""..change_name..""\")")
+  end
+end
+
+-- do node change with change_name
+function default.apply_node_change(pos, node, change_name)
+  if (node==nil) then
+    node = minetest.get_node(pos);
+  end
+  
+  changable_node = default.registered_changeable_nodes[node.name];
+  
+  if (changable_node~=nil) then
+    change_def = changable_node.changes[change_name];
+    if (change_def~=nil) then
+      if ((change_def.allow_change==nil)||(change_def.allow_change(pos, node)==true) then
+        minetest.swap_node(pos, {name=change_def.new_node_name});
+        if (change_def.check_stability==true) then
+          minetest.check_for_falling(pos);
+          default.neighbour_stable_to_normal(pos);
+          minetest.after(1, default.check_neighbour_for_fall, pos);
+        end
+        return true;
+      end
+    end
+  end
+  
+  return false;
+end
+
+-- test if node can be changed with change_name
+function default.is_node_changeable(pos, node, change_name)
+  if (node==nil) then
+    node = minetest.get_node(pos);
+  end
+  
+  changable_node = default.registered_changeable_nodes[node.name];
+  
+  if (changable_node~=nil) then
+    change_def = changable_node.changes[change_name];
+    if (change_def~=nil) then
+      return true;
+    end
+  end
+  
+  return false;
+end