AddAlphaControlPoint
This function sets an Alpha control point that controls a particle's alpha transparency over the course of its life.
Syntax
- AddAlphaControlPoint(number time, number alpha)
Parameters
- time: - a float between 0.0 and 1.0 with 0 being the particle's birth and 1 being the particle's death.
- alpha: - a value between 0.0 and 1.0 stating the alpha value at given time. 0 being transparent and 1 being opaque.
Remarks
Alpha control points work by interpolation from control point to control point over a particles lifetime. For example, if there is a control point at 0.0 with an alpha of 0.0 and a control point at 1.0 with an alpha of 1.0 the particle will gradual fade in over it's lifetime.
Example
--Create a window
window = Window:Create()
context = Context:Create(window)
world = World:Create()
camera = Camera:Create()
camera:Move(0,0,-3)
local light = DirectionalLight:Create()
light:SetRotation(35,35,0)
--Create an emitter
emitter = Emitter:Create(100)
emitter:ClearAlphaControlPoints() --Remove default control points
emitter:AddAlphaControlPoint(0,0) --at spawn the particle will have an alpha of 0 (fully transparent)
emitter:AddAlphaControlPoint(.5,1) --halfway through the particle's lifetime alpha will be 1 (ie not transparent)
emitter:AddAlphaControlPoint(1,0) --at death the particle will be fully transparent
while true do
if window:Closed() or window:KeyHit(Key.Escape) then return false end
Time:Update()
world:Update()
world:Render()
context:Sync()
end