private Vector3f rotateDirection(float angle, Vector3f l, Vector3f store) {
        float s, c, t;

        s = FastMath.sin(angle);
        c = FastMath.cos(angle);
        t = 1.f - c;

        store.x = l.x * c + l.y * s;
        store.y = -l.x * s + l.y * c;
        store.z = l.z * (t + c);
        return store;
    }
Generates the prefiltered env map (used for image based specular
lighting) With the GGX/Schlick brdf
{@link EnvMapUtils#getSphericalHarmonicsCoefficents(com.jme3.texture.TextureCubeMap)}
Note that the output cube map is in RGBA8 format.

@param sourceEnvMap
@param targetMapSize  the size of the irradiance map to generate
@param store
@param fixSeamsMethod the method to fix seams
@return The irradiance cube map for the given coefficients
jme3-core/src/main/java/com/jme3/environment/generation/PrefilteredEnvMapFaceGenerator.java