private float samplePixel(CubeMapWrapper envMapReader, Vector3f lWorld, float NoL, float computedMipLevel, Vector3f store) {

        if (NoL <= 0) {
            return 0;
        }
        envMapReader.getPixel(lWorld, computedMipLevel, c);
        store.setX(store.x + c.r * NoL);
        store.setY(store.y + c.g * NoL);
        store.setZ(store.z + c.b * NoL);

        return NoL;
    }
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