If Left click ffi in lua

Question

I'm new to ffi.

Basically I'm trying to get a bool when the mouse left button is clicked.

I've done some research and found something called WM_LBUTTONDOWN

However I don't know how to put it in ffi.cdef then getting a bool.

Answer 1

This program polls the mouse button state once per 1 ms and exits when LMB is pressed

local ffi = require("ffi")
ffi.cdef[[
   short GetAsyncKeyState(int vKey);
   void Sleep(int ms);
]]

local function is_key_down(vKey)
   return ffi.C.GetAsyncKeyState(vKey) < 0
end

local function sleep(ms)
   ffi.C.Sleep(ms or 1)
end

local VK_LBUTTON  = 0x01 -- Left mouse button
local VK_RBUTTON  = 0x02 -- Right mouse button
local VK_MBUTTON  = 0x04 -- Middle mouse button
local VK_XBUTTON1 = 0x05 -- X1 mouse button (Back)
local VK_XBUTTON2 = 0x06 -- X2 mouse button (Forward)

sleep(1000)
print"Waiting for Left Mouse Button pressed"
repeat
   sleep()
until is_key_down(VK_LBUTTON)
print"Left Mouse Button is down now"

If you want to handle WM_LBUTTONDOWN message that would be a more complex solution.