attempt to redefine 'UndefinedFilter' at line 41

any idea what this indicates?

Failed to load and run script from 
ERROR[main]: .../.minetest/mods/realterrain/init.lua:
ERROR[main]: .../.minetest/mods/realterrain/graphicsmagick/Image.lua:295: attempt to redefine 'UndefinedFilter' at line 41
ERROR[main]: stack traceback:
ERROR[main]:    [C]: in function 'cdef'
ERROR[main]:    .../.minetest/mods/realterrain/graphicsmagick/Image.lua:295: in main chunk
ERROR[main]:    [C]: in function 'require'
ERROR[main]:    .../.minetest/mods/realterrain/graphicsmagick/init.lua:2: in main chunk
ERROR[main]:    [C]: in function 'require'
ERROR[main]:    ....minetest/mods/realterrain/init.lua:32: in main chunk

[nagadomi]

Maybe UndefinedFilter is conflicting with other ffi based library in your development environment.

Example:

local gm = require 'graphicsmagick'
-- redefine
local ffi = require 'ffi'
ffi.cdef [[
typedef enum {
  UndefinedFilter
} FooBar;
]]

% th ffi_cdef_conflict.lua 
/home/nagadomi/torch/install/bin/luajit: ffi_cdef_conflict.lua:8: attempt to redefine 'UndefinedFilter' at line 2
stack traceback:
    [C]: in function 'cdef'
    ffi_cdef_conflict.lua:8: in main chunk
    [C]: in function 'dofile'
    ...domi/torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:133: in main chunk
    [C]: at 0x00405ea0

thanks, that helped me fix that. the lua imagemagick library was conflicting.

now I have this:

graphicsmagick/info.lua:3: module 'sys' not found

is it really necessary to install torch just to use the basic image handling functions?

[soumith]

I think it is. we only test and build stuff in the torch environment. Considering the ins and outs of this library are torch tensors, maybe pretty essential.

yes but there are plenty of features that have nothing to do with tensors, such as all the features of graphicsmagick that replace imagemagick, such as reading images from files, pixel access, etc.

by deleting the sys calls at the tops of convert.lua, and info.lua that check to see if the command is present, this library loaded for me. perhaps for users that only want to use non-tensor features you could change the method used to check for the presence of convert and info commands?