Engine Hunk Overflow

What Does It Mean?

Engine Error

This is an engine error message that occurs when attempting to load the map in-game. This is related to Lightmap values being modified to an odd value.

What Is Hunk Allocation

This is described as the memory allocated for light data.

• 0 = to normal "program memory" with alloc
• 1 = to Valve's seemingly limited to certain size "MemoryStack memory" with Hunk_Alloc

Methods To Fixing The Error

• +r_hunkalloclightmaps 0
  • Add this in your launch options. This will eliminate the error altogether. While fine for singleplayer games, it is not recommended for multiplayer games, as not only will you have to add this to your launch options, but server operators will also have to add it to their server command line.
    

Note: acknowledges the issue with Hunk Allocation. Garry's Mod has ConVar r_hunkalloclightmaps set to 0 by default.

Note: has ConVar r_hunkalloclightmaps set to 1 by default, but it has been hidden; it cannot be changed.

• Find faces with odd or extreme lightmap values.
  • Very large displacements can cause this error. The lightmap value can automatically change (sometimes, to an undesired value). Split them up and/or make sure your lightmap is an even value of a power of 2, avoiding extreme numbers. Having stretched displacements in one dimension can also cause it.
  • If you can't find any odd lightmap values, as a last resort, select the entire map, open the Face Edit Sheet and input 16 for the lightmap scale.
  • If reverting the entire map's lightmap value to 16 does not suit you due to high amount of work on lightmap, make use of the Cordon Bound Tool to determine if the Engine Hunk Overflow error is caused by the lightmap data as a whole (i.e. related to the size of the map) or by a certain brush or set of brushes.
  • Sometimes increasing the Lightmap value on brushes can fix it.