local pos = there
local emitter = ParticleEmitter(vector_origin)

local particles = {}

local function collide(self, pos, normal)
    WorldSound("npc/headcrab_poison/ph_step"..math.random(2,4)..".wav", pos, 60, math.random(25, 70))
end

local function Think()
    local clr2 = HSVToColor(CurTime()*30%360, 0.5, 1)
    local clr = HSVToColor(CurTime()*30%360, 0.5, 1)
    clr.a = 255
    for i =1, 2 do
    local particle = emitter:Add("sprites/light_glow02_add", pos)

    -- movement
    particle:SetVelocity(Vector(math.Rand(-1, 1), math.Rand(-1, 1), math.Rand(2.5, 5)) * 100)
    particle:SetAirResistance(0)
    particle:SetGravity(physenv.GetGravity()*0.5)

    particle:SetCollide(true)
    particle:SetBounce(0.25)

    -- appearance
    particle:SetColor(clr2.r, clr2.g, clr2.b)
    particle.clr = clr

    particle:SetStartAlpha(255)
    particle:SetEndAlpha(0)

    particle:SetStartSize(10)
    particle:SetEndSize(0)

    particle:SetDieTime(math.Rand(1.5, 2.5))

    particle:SetStartLength(0)
    particle:SetEndLength(0)
        particle:SetCollideCallback(collide)

    table.insert(particles, particle)
    end
end

local mat = Material("particle/Particle_Glow_04_Additive")

hook.Add("PostDrawTranslucentRenderables", 1, function()
    for key, particle in pairs(particles) do
        local delta = particle:GetDieTime() - particle:GetLifeTime()
        if delta > 0 then
            render.SetMaterial(mat)
            render.DrawBeam(particle:GetPos() + particle:GetVelocity()*0.05, particle:GetPos() - particle:GetVelocity() * 0.25, 1 * delta, 0, 1, particle.clr)
        else
            particles[key] = nil
        end
    end
end)

hook.Add("Think", "particle_test", Think)