WaterFilter and Particles

[monkey]

Hey,



I tried out the water test and it looks awsome.

I tried out putting a particleemitter in the water (half in half out) and it doesn’t render anything below the water the particleemitter is just cut into half.



Any ideas?





Another question is: is there a way to create a ball of water?

[normen]

Which water? If you mean the simple water I guess your particle emitter is not attached to the right node so it cannot be reflected. https://wiki.jmonkeyengine.org/legacy/doku.php/jme3:advanced:water

No waterballs, with a reflection map you can maybe achieve a similar effect.

[Momoko_Fan]

TestCubeMap is kind of like a water ball, except that it reflects/refracts a cubemap, so it is not exactly correct.

[monkey]

Without water:





With water:





Sphere centre points are on ZX plane where Y is 0

[Momoko_Fan]

I might have to ask Remy/nehon about this, it seems particles and filters are natural born enemies or something X_X

[nehon]

mhhh strange…could you give a test case?



thats not only the particles I guess, because the water is only visible around the spheres.

[monkey]

It actually almost works if you look straight down on the water, I can see the reflection for a moment.

[java]

import com.jme3.app.SimpleApplication;

import com.jme3.effect.ParticleEmitter;

import com.jme3.effect.ParticleMesh;

import com.jme3.light.DirectionalLight;

import com.jme3.material.Material;

import com.jme3.math.ColorRGBA;

import com.jme3.math.Vector3f;

import com.jme3.post.FilterPostProcessor;

import com.jme3.water.WaterFilter;



public class TestParticleWater extends SimpleApplication {

public static void main(String[] args) {

TestParticleWater test = new TestParticleWater();

test.start();

}



private FilterPostProcessor fpp;

private WaterFilter water;

private float initialWaterHeight = 0.0f;

private Vector3f lightDir = new Vector3f(-4.9236743f, -1.27054665f,

5.896916f);



@Override

public void simpleInitApp() {

fpp = new FilterPostProcessor(assetManager);

water = new WaterFilter(rootNode, lightDir);

//

water.setWaterHeight(initialWaterHeight);

water.setWaterTransparency(0.05f);

fpp.addFilter(water);

viewPort.addProcessor(fpp);



ParticleEmitter fire = new ParticleEmitter("Emitter",

ParticleMesh.Type.Triangle, 30);

Material mat_red = new Material(assetManager,

"Common/MatDefs/Misc/Particle.j3md");

mat_red.setTexture("m_Texture",

assetManager.loadTexture("Effects/Explosion/flame.png"));

fire.setMaterial(mat_red);

fire.setImagesX(2);

fire.setImagesY(2); // 2x2 texture animation

fire.setEndColor(new ColorRGBA(1f, 0f, 0f, 1f)); // red

fire.setStartColor(new ColorRGBA(1f, 1f, 0f, 0.5f)); // yellow

fire.setInitialVelocity(new Vector3f(0, 2, 0));

fire.setStartSize(1.5f);

fire.setEndSize(0.1f);

fire.setGravity(0);

fire.setLowLife(0.5f);

fire.setHighLife(3f);

fire.setVelocityVariation(0.3f);

rootNode.attachChild(fire);



DirectionalLight sun = new DirectionalLight();

sun.setDirection(new Vector3f(-0.1f, -0.7f, -1.0f));

rootNode.addLight(sun);

}



}

[/java]

[Momoko_Fan]

This is the depth write issue.

Particle is not detected as an “object” by the water because it doesn’t write depth.

If you enable depth write, you get artifacts since you don’t have depth sort per-particle and because the water only blends it when the depth allows it, its a yes or no kind of thing.

Alpha to coverage does not work also since depth is not altered.



We might need to write alpha value for a pixel, and then use it to blend in the water effect.

[benkibitzer]

Sorry for revivng this old thread but I’m also having trouble with Particle Effects being inside the water…

I guess it is a noob - question, but how exactly do I

enable depth write

?

[nehon]

particle.getMaterial().getAdditionalRenderState().setDepthWrite(true);

[benkibitzer]

Thank you very much !

[neuweiler]

Also sorry for digging up a decade old thread. Setting depth write causes something to be rendered in front of water filter. But the result is strange.

Effect of a missile’s smoketrail with depth write false: (default, looks ok in front of objects/sky but invisible in front of water):

Effect with depth write true in front of water → grey boxes

Effect with depth write true in front of terrain → intransparent smoke plumes which get wiped away from the bottom (see red arrows, with setEndSize(5)):

With that I’d rather leave depth write set to false. Any idea ?

[pspeed]

This may be helpful:

Alpha/Transparency Sorting, Your Z-buffer, and You

Since this comes up every three or four days, I decided to put together some visual aids. There is often a lot of confusion with how pixels get processed in relation to the z-buffer and why sorting is important. Most importantly it can be mind-warping trying to wrap one’s head around how to ‘fix’ the cases where proper sorting isn’t possible. Hopefully these diagrams help show the futility of it all… I mean the trade offs one has to make to get transparency looking its best in the general cas…

As for interaction with the water, you may have to mess with the translucent filter and translucent bucket to get them to render after the water instead of before. I think there are threads about that more recent than 11 years ago.