Aseprite script to generate a 2d light sprite for Godot

Generate2DLight.lua

-- Generate a 2d light for Godot

local rgba = app.pixelColor.rgba

local cel = app.activeCel
if not cel then
    return app.alert("There is no active image")
end

local bounds = cel.bounds
local width = bounds.width
local height = bounds.height

local img = cel.image
if img.colorMode ~= ColorMode.RGB then
    return app.alert("Active image must be RGB color mode")
end

for it in img:pixels() do
    local x = it.x
    local y = it.y

    local dx = math.abs(x - width/2)
    local dy = math.abs(y - height/2)
    local distanceFromCenter = math.sqrt(dx * dx + dy * dy)

    local maxDistance = math.min(width/2, height/2)
    local brightness = (1-distanceFromCenter/maxDistance)
    if distanceFromCenter > maxDistance then
        brightness = 0
    end

    brightness = math.sqrt(brightness)
    brightness = brightness * 255

    local color = rgba(255,255,255,brightness)
    it(color)
end

Result: