This function sets an Alpha control point that controls a particle's alpha transparency over the course of its life.

Syntax

• void AddAlphaControlPoint(float time, float 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

#include "Leadwerks.h"

using namespace Leadwerks;

int main(int argc, const char *argv[])
{
    Leadwerks::Window* window = Leadwerks::Window::Create();
    Context* context = Context::Create(window);
    World* world = World::Create();
    Camera* camera = Camera::Create();
    camera->SetRotation(35, 0, 0);
    camera->Move(0, 0, -3);
    Light* light = DirectionalLight::Create();
    light->SetRotation(35, 35, 0);
    
    //Create an emitter
    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)
    {
        if (window->Closed() || window->KeyDown(Key::Escape)) return false;

        Leadwerks::Leadwerks::Time::Update();
        world->Update();
        world->Render();

        //if the space key is pressed all alpha control points are removed
        if (window->KeyDown(Key::Space)) emitter->ClearAlphaControlPoints();

        context->Sync();
    }
}