Roblox Lens Flare Effect

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-- @CloneTrooper1019, 2018 <3
-- Lens Flare Effect
-- A remake of Roblox's 2007 Lens Flare
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-- Configuration
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-- Classic Style

local LENS_FLARE_CONFIGURATION =
{
    Scale = 1/8;
    Texture = "rbxasset://textures/whiteCircle.png";
    Transparency = 0.9;
}

-- Modern Style

--local LENS_FLARE_CONFIGURATION =
--{
--
--  Scale = 1/3;
--  Texture = "rbxasset://textures/shadowblurmask.png";
--  Transparency = 0.7;
--}

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-- Lenses
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--[[
    The LENSES array is used to control the individual lenses of the effect.

    * Color     - The color of the lense.
    * Radius    - An arbitrary scaling factor for each lense.
    * Distance  - A value between 0 and 1 indicating the position of the lense on the screen.
                  ( A value of 0.5 will be at the center of the screen )
                  ( A value of 1.0 will be directly on top of the sun )
                  ( A value of 0.0 will be on the opposite end of the screen )

--]]

local LENSES =
{
    { Color = Color3.fromRGB(200, 255, 200), Radius = 1.00, Distance = 0.000 };
    { Color = Color3.fromRGB(  0, 255,   0), Radius = 0.50, Distance = 0.200 };
    { Color = Color3.fromRGB(255,   0,   0), Radius = 0.30, Distance = 0.225 };
    { Color = Color3.fromRGB(255, 170,   0), Radius = 1.50, Distance = 0.250 };
    { Color = Color3.fromRGB(255, 170,   0), Radius = 3.00, Distance = 0.250 };
    { Color = Color3.fromRGB(  0, 255,   0), Radius = 0.50, Distance = 0.300 };
    { Color = Color3.fromRGB(  0, 255,   0), Radius = 0.20, Distance = 0.600 };
    { Color = Color3.fromRGB(  0, 255,   0), Radius = 0.40, Distance = 0.650 };
    { Color = Color3.fromRGB(255,   0,   0), Radius = 0.20, Distance = 0.780 };
    { Color = Color3.fromRGB(  0, 255,   0), Radius = 0.25, Distance = 0.900 };
    { Color = Color3.fromRGB( 63,  63,  63), Radius = 0.15, Distance = 1.200 };
    { Color = Color3.fromRGB( 63,  63,  63), Radius = 0.15, Distance = 1.500 };
}

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-- Constants
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local RunService = game:GetService("RunService")
local Lighting = game:GetService("Lighting")

local c = workspace.CurrentCamera
local lensFlareNode = c:FindFirstChild("LensFlareNode")
if lensFlareNode then
    lensFlareNode:ClearAllChildren()
else
    lensFlareNode = Instance.new("Part")
    lensFlareNode.Name = "LensFlareNode"
    lensFlareNode.Transparency = 1
    lensFlareNode.Anchored = true
    lensFlareNode.CanCollide = false
    lensFlareNode.Locked = true
    lensFlareNode.Parent = c
end

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-- Main
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local function as_Vector2(v3,...)
    -- Roblox likes to kill my OCD.
    return Vector2.new(v3.X,v3.Y),...
end

local function isSunOccluded(sunDir)
    local origin = c.CFrame.p + (c.CFrame.lookVector*2)
    local ray = Ray.new(origin,origin + (sunDir * 10e6))
    local ignore = {}
    local occluded = false
    while true do
        local hit,pos = workspace:FindPartOnRayWithIgnoreList(ray,ignore)
        if hit then
            local t = hit.Transparency + hit.LocalTransparencyModifier
            if t <= 0 then
                occluded = true
                break
            else
                table.insert(ignore,hit)
            end
        else
            break
        end
    end
    return occluded
end

local function createLenseBeam(lense,id)
    local radius = lense.Radius * LENS_FLARE_CONFIGURATION.Scale

    local a0 = Instance.new("Attachment")
    a0.Name = id .. "_A0"
    a0.Parent = lensFlareNode
    lense.A0 = a0

    local a1 = Instance.new("Attachment")
    a1.Name = id .. "_A1"
    a1.Parent = lensFlareNode
    lense.A1 = a1

    local beam = Instance.new("Beam")
    beam.Name = id
    beam.Color = ColorSequence.new(lense.Color)
    beam.Width0 = radius
    beam.Width1 = radius
    beam.TextureSpeed = 0
    beam.LightEmission = 1
    beam.Texture = LENS_FLARE_CONFIGURATION.Texture
    beam.Attachment0 = a0
    beam.Attachment1 = a1
    beam.Transparency = NumberSequence.new(LENS_FLARE_CONFIGURATION.Transparency)
    beam.Parent = lensFlareNode
    lense.Beam = beam

    return beam
end

local function updateLensFlare()
    local vpSize = c.ViewportSize
    local sunDir = Lighting:GetSunDirection()
    local sunWrldSpace = sunDir * 10e6
    local sunScrnSpace,inView = as_Vector2(c:WorldToViewportPoint(sunWrldSpace))
    local sunScrnSpaceInv = c.ViewportSize - sunScrnSpace
    local enabled = (inView and not isSunOccluded(sunDir))

    for i,lense in ipairs(LENSES) do
        local beam = lense.Beam or createLenseBeam(lense,i)
        beam.Enabled = enabled
        if enabled then
            local radius = lense.Radius * LENS_FLARE_CONFIGURATION.Scale
            local lenseSP = sunScrnSpaceInv:lerp(sunScrnSpace,lense.Distance)
            local lenseWP = c:ViewportPointToRay(lenseSP.X,lenseSP.Y,1).Origin
            local lenseCF = CFrame.new(lenseWP,lenseWP - sunDir)
            lense.A0.CFrame = lenseCF * CFrame.new(-radius/2,0,0)
            lense.A1.CFrame = lenseCF * CFrame.new(radius/2,0,0)
        end
    end
end

RunService:BindToRenderStep("UpdateLensFlare",201,updateLensFlare)

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