Particle system fade out affector not working

[Donald Duck]

I'm trying to make a particle system in Irrlicht with a fade out affector. Here is my code:

Code: Select all

irr::scene::IParticleSystemSceneNode *particleSystem = sceneManager->addParticleSystemSceneNode(true, 0, -1, irr::core::vector3df(0, 0, 0), irr::core::vector3df(0, 0, 0), irr::core::vector3df(1, 1, 1));
irr::scene::IParticleEmitter *emitter = particleSystem->createBoxEmitter(irr::core::aabbox3d<irr::f32>(-0.03f, 0, -0.03f, 0.03f, 0.01f, 0.03f), irr::core::vector3df(0, 0.0001f, 0), 3, 7, irr::video::SColor(0, 0, 0, 0), irr::video::SColor(0, 20, 20, 20), 5000, 6000, 10, irr::core::dimension2df(0.06f, 0.06f), irr::core::dimension2df(0.12f, 0.12f));
particleSystem->setEmitter(emitter);
emitter->drop();
particleSystem->setMaterialTexture(0, driver->getTexture("image.png"));
particleSystem->setMaterialType(irr::video::EMT_TRANSPARENT_ALPHA_CHANNEL);
particleSystem->setMaterialFlag(irr::video::EMF_LIGHTING, false);
irr::scene::IParticleAffector *affector = particleSystem->createFadeOutParticleAffector(irr::video::SColor(0, 0, 0, 0), 7000);
particleSystem->addAffector(affector);
affector->drop();

Here is image.png:



The problem is that the fade out affector doesn't do anything. I get exactly the same result if I comment the last three lines.

How can I get it to work?

[CuteAlien]

That one does set the vertex-color, so it has to be a material which does use the vertex-color. Documentation says it will work well with EMT_TRANSPARENT_ADD_COLOR. I guess EMT_TRANSPARENT_ALPHA_CHANNEL probably ignores vertex-colors so if you would like that specific kind of color-combination you will need to use a shader.

[Donald Duck]

I tried EMT_TRANSPARENT_ADD_COLOR and then the particle system was completely invisible. That's probably because as far as I understand, EMT_TRANSPARENT_ADD_COLOR changes everything that's black to transparent and since the texture is either black or transparent everywhere, it becomes completely transparent. That's why I used EMT_TRANSPARENT_ALPHA_CHANNEL. What's the solution to this?

[CuteAlien]

Sorry, I don't think there is a default material which mixes the alpha of vertices and textures. I suppose this needs a custom shader.

[MartinVee]

Have you tried..?

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  setMaterialType(video::EMT_ONETEXTURE_BLEND);
  setMaterialFlag(EMF_COLOR_MATERIAL, true);
 
  getMaterial(0).MaterialTypeParam = irr::video::pack_textureBlendFunc(irr::video::EBF_SRC_ALPHA, irr::video::EBF_ONE_MINUS_SRC_ALPHA, irr::video::EMFN_MODULATE_1X, irr::video::EAS_TEXTURE | irr::video::EAS_VERTEX_COLOR);
  getMaterial(0).setFlag(EMF_BLEND_OPERATION, true);
 

[kornwaretm]

I tried EMT_TRANSPARENT_ADD_COLOR and then the particle system was completely invisible. That's probably because as far as I understand, EMT_TRANSPARENT_ADD_COLOR changes everything that's black to transparent and since the texture is either black or transparent everywhere, it becomes completely transparent. That's why I used EMT_TRANSPARENT_ALPHA_CHANNEL. What's the solution to this?

if you want an easy solution, use EMT_TRANSPARENT_ADD_COLOR and don't use black as the primary object color(in irrlicht media folder there is one or two texture sample). if you still need it black, than you need shader as CuteAlien mentioned. use EMT_TRANSPARENT_ALPHA_CHANNEL, and in shader just multiply texture alpha with vertex alpha, this way, you will get both the texture alpha and the fading alpha.