I thought I would not be that guy but I could not help myself.
I think the problem is that the function you pass in the second parameter of package.loadlib is meant to be a initialisation routine for the library you define, rather than a custom function to be called in the script. It has a required form of "int init(lua_State*).
This should work:
keystate.dll:
C++:
#include <windows.h>
extern "C" {
#include "Lua\lua.h"
#include "Lua\lualib.h"
#include "Lua\lauxlib.h"
}
int my_key_pressed(lua_State * L)
{
int virtualKeyCode = lua_tointeger(L, 1);
lua_pushboolean(L, GetAsyncKeyState(virtualKeyCode) & 0x8000 ? 1 : 0);
return 1;
}
extern "C" __declspec(dllexport) int init(lua_State * L)
{
static const struct luaL_Reg testlib[] = {
{"mykeypressed", my_key_pressed},
{NULL, NULL}
};
luaL_register(L, "testlib", testlib);
return 1;
}
Script:
Code:
keylib = package.loadlib("keystate.dll", "init");
if keylib then
msg1 = "DLL loaded successfully"
else
msg1 = "Error loading DLL"
end
keylib()
note = oapi.create_annotation()
note:set_pos (0.25,0.15,0.9,0.95)
note:set_colour ({r=1,g=0.6,b=0.2})
goals = 0
while goals < 1 do
keyPressed = testlib.mykeypressed(0x41) -- 0x41 is the virtual key code for the 'A' key
if keyPressed then
msg =("A key is pressed")
else
msg =("A key is not pressed")
end
note:set_text(msg1.." "..msg)
proc.skip()
if goals > 0 then end
end
It registers the key checking function as a library function. The function itself pulls the requested virtual key code from the lua stack (where it was left from the input argument), and pushes the result back to the stack (where it is available as a return value).
Note that the script, after loading the library, has to call the initialisation routine ("keylib()"), so that the registration is actually performed.
Something that confused the hell out of me when I was trying to find a solution was the fact that the name of the library you register in the initialisation routine (here: "testlib") must not be the same as the name of the library you assign to the return value of the package.loadlib call (here: "keylib"). Otherwise you overwrite the library you just created in the global namespace, and all its methods mysteriously disappear.
I didn't think I would be that guy but I guess I decided to be. Simplified this and it should still work.
keylib = package.loadlib("keystate.dll", "init")
msg1 = keylib and "DLL loaded successfully" or "Error loading DLL"
if keylib then keylib() end
note = oapi.create_annotation()
note:set_pos(0.25, 0.15, 0.9, 0.95)
note:set_colour({r=1, g=0.6, b=0.2})
while true do
keyPressed = testlib.mykeypressed(0x41) -- 'A' key
msg = keyPressed and "A key is pressed" or "A key is not pressed"
note:set_text(msg1 .. " " .. msg)
proc.skip()
end
I combined the DLL check and message assignment using a ternary operator
The goals variable was replaced with while true as unless it's used outside of the script, it does not activate in any capacity other to perform as a loop that can never be disabled.
The original code will
always attempt to call keylib() regardless of whether the DLL loaded successfully which would cause an error if keylib is nil. My version adds a safety check. If that is intentional functionality, then
keylib = package.loadlib("keystate.dll", "init")
msg1 = keylib and "DLL loaded successfully" or "Error loading DLL"
keylib() -- Always call, just like the original
