Custom WebMat problem.

[Rainbow_Cow]

Hi, I made a somewhat working web mat addon. However the Material returns nil the first time called, and works the second. Any idea why it does not work the first time? Here's the code:

WebMats = WebMats or {}
if not file.Exists("webtextures", "DATA") then
file.CreateDir("webtextures")
end

function WebMats:Fetch(url, flags)
local uid = util.CRC(url) .. ".png"
local iMat

if file.Exists("webtextures/" .. uid, "DATA") then
iMat = Material("../data/webtextures/" .. uid, flags)
return iMat
end

http.Fetch(url, function(body, len, headers, code)
file.Write("webtextures/" .. uid, body)
iMat = Material("../data/webtextures/" .. uid, flags)
return iMat
end)
end

[tobiasxzz]

Its because http.Fetch is not async with its callbacks.

You'd probably want to make a callback function like so:

WebMats = WebMats or {}
if not file.Exists("webtextures", "DATA") then
file.CreateDir("webtextures")
end

function WebMats:Fetch(url, flags, callback)
    local uid = util.CRC(url) .. ".png"
    local iMat

    if file.Exists("webtextures/" .. uid, "DATA") then
        iMat = Material("../data/webtextures/" .. uid, flags)
        if (callback) then
            callback(iMat);
        end
          return iMat
      end

      http.Fetch(url, function(body, len, headers, code)
          file.Write("webtextures/" .. uid, body)
          iMat = Material("../data/webtextures/" .. uid, flags)
        if (callback) then
            callback(iMat);
        end
        return iMat
    end)
end

--Example usage
/*
    WebMats:Fetch("http://google.com/image.png", "noclamp", function(mat)
        surface.SetDrawColor(255, 255, 255, 255);
        surface.SetMaterial(mat);
        surface.DrawTexturedRect(0, 0, 64, 64);
    end)
*/