jMonkeyEngine.org

It looks jme3 already have a fog filter, and you can add it to the app easily by using the Filter Processors plugin.

A fog filter can be done with just a few lines added to the end of Lighting. The reason the JME crew are reluctant to continue shoehorning things into Lighting.j3md is because it’s already pretty bloated.

I don’t know if there’s a better way, but I calculate my own z varying in my vert shader and then use that in the frag shader to tweak the colors right at the end to mix in a fog based on distance. If you’ve never modified a shader before then it’s probably a pretty daunting task, though.

I wouldn’t mind supplying fog parameters to each of my materials if it meant full fog effects (I don’t have too many materials anyway). I will try the translucent bucket thing – however, I still want fog applied to the water (and the stuff behind it).

WaterFilter is really one of its kind because it’s a 2D post process that actually renders a 3D object in the scene….it’s pretty tricky to make it fit with every other features…

I’m not using a WaterFilter… my “water” is just a large semi-transparent quad that acts as the water surface (same goes for my cloud layers). Would the material method work for this? I’m really willing to try (almost) anything to get a decent fog system working, since just about every other part of my game is “complete”.

What is this “material” way, anyway? And how could I implement it?

In my case, I add a varying to my .vert and .frag:

varying float my_z;

I also have a uniform for fog color and I use the alpha channel of the fog color for distance.

And then in the main of my .vert after gl_Position is calculated:
my_z = gl_Position.z;

Then in my .frag’s main at the end:

    float fogDensity = 1.2;
    vec4 fogColor = m_FogColor;
    float fogDistance = fogColor.a;
    fogColor.a = 1.0;

    float depth = my_z / fogDistance; 

    float fogFactor = exp2( -fogDensity * fogDensity * depth *  depth * LOG2 );
    fogFactor = clamp(fogFactor, 0.0, 1.0);
    gl_FragColor =mix(fogColor,gl_FragColor,fogFactor);

I don’t know if it’s the best way but it works for me. I calculate material alpha separately and apply it after the fog mix.

And if forking the lighting material and adding the above sounds scary then it’s best to steer clear. Editing GLSL is not for the faint of heart.

I’m not going to bother to manually quote because I have no patience for that today.

Yeah, I know that’s what you were talking about with the “material way”. I just don’t know if it’s the best way to do the “material way”. I generally whack at things until they look like I want them to and then treat them like they are covered with thorns.

It doesn’t have to be the lighting shader. That code snippet could be added to most shaders. As long as you can provide the z value to my_z in the .vert and do the gl_FragColor fog mix at the end of the .frag you are fine.

I don’t really want to post my whole shader, though.