local ENT = this
local size = 256

local count = 100
local sand = {}

for i=1, count do
    sand[i] =
    {
        pos = Vector(size*0.5,size*0.5, 0),
        vel = vector_origin,
    }
end

local function drawpixel(i)
    surface.SetTextPos(sand[i].pos.x, sand[i].pos.y)
    surface.DrawText(string.char(math.random(32, 128)))
    --[[ace.DrawLine(
        sand[i].pos.x,
        sand[i].pos.y,

        sand[i].pos.x+1,
        sand[i].pos.y+1
        --sand[math.min(i+1, count)].pos.x,
        --sand[math.min(i+1, count)].pos.y
    )]]
end

local new
local function localtoworld(vec, ang)
    new = WorldToLocal(vec, Angle(0), Vector(0), ang)
    new:Rotate(Angle(0,-90,0))
    return new
end
local vel
local function DrawScreen()
    surface.SetDrawColor(0,0,0,120)
    surface.DrawRect(0,0,size,size)

    surface.SetDrawColor(200,230,255,255)
    surface.SetTextColor( 200, 230, 255, 255 )
    surface.SetFont("DefaultFixedOutline")

    local newvel = localtoworld(ENT:GetVelocity(), ENT:GetAngles()) * 0.5

    for i, part in pairs(sand) do

        vel = vel + newvel
        vel = vel + VectorRand() * 2

        sand[i].pos = sand[i].pos + (sand[i].vel * FrameTime())

        sand[i].vel = vel + (sand[i].vel * 0.99)

        if sand[i].pos.x < 0 then
            sand[i].pos.x = 1
            sand[i].vel.x = -sand[i].vel.x * math.random()
        end
        if sand[i].pos.x > size then
            sand[i].pos.x = size-1
            sand[i].vel.x = -sand[i].vel.x * math.random()
        end
        if sand[i].pos.y < 0 then
            sand[i].pos.y = 1
            sand[i].vel.y = -sand[i].vel.y * math.random()
        end
        if sand[i].pos.y > size then
            sand[i].pos.y = size-1
            sand[i].vel.y = -sand[i].vel.y * math.random()
        end


        drawpixel(i)
    end
end

local new = GetRenderTarget("test_rt", size, size, true)

local function main()
    local old, w, h = render.GetRenderTarget(), ScrW(), ScrH()

    render.SetRenderTarget(new)
         -- render.Clear(68,112,146, 50, false)
        render.SetViewPort(0, 0, size, size)
            cam.Start2D()
                DrawScreen()
            cam.End2D()
        render.SetViewPort(0, 0, w, h)
    render.SetRenderTarget(old)
end


local mat = CreateMaterial("test_rt_mat", "VertexLitGeneric",
    {
        ["$basetexture"] = "test_rt",
    }
)

ENT:SetModelScale(Vector())

function ENT:RenderOverride()
    main()

    SetMaterialOverride(mat)
        self:DrawModel()
    SetMaterialOverride()
end