Magic: Drawing from the world

Part of my experimentation with ideas for interesting magic systems

In this system mana, the resource consumed when casting spells, must be drawn from a physical location in the world.  Each player has a variable reach around themselves within which they can draw in mana.

(Player’s view. The dashed circle represents their reach. Notice that the inside is dark as mana has been drained from this area)

The idea here was to create a tactical element to gathering mana, which should force players to move around more as they deplete all sources in their area.


To achieve this in Garry’s Mod I used a 2d array representing positions on the map (no verticality). Whenever the array is altered, each client is notified to update their mana render texture (a top down view of the map with black squares where mana has been consumed). This texture is then used to project light onto the map from above, leading to the effect pictured.

(An aerial view of the map. Black areas are void of mana, having been consumed by a player)