Here is something that seems to work with Gimp :
#@gui Emboss-ReliefTEST : fx_emboss_reliefTEST, fx_emboss_reliefTEST(0)
#@gui : Enable Extreme Emboss or Relief? = bool(0)
#@gui : Angle = float(0,0,360)
#@gui : Depth (%) = float(100,0,500)
#@gui : Depth (%) = float(100,0,5000)
#@gui : Smoothness = float(0,0,10)
#@gui : Invert Embossing? = bool(0)
#@gui : Preserve Alpha? = bool(1)
#@gui : sep = separator(), note = note("Relief Section")
#@gui : Apply Relief? = bool(1)
#@gui : Blending Opacity (%) = float(100,0,100)
#@gui : sep = separator(), note = note("<small>Author: Reptorian. Latest Update: <i>2019/3/19</i>.</small>")
fx_emboss_reliefTEST :
split_opacity
if $8
+em {$6?$2+180:$2},{$1?$4/100:$3/100},$5
blend grainmerge,{$9/100}
else
em {$6?$2+180:$2},{$1?$4/100:$3/100},$5
blend grainmerge,{$9/100}
fi
if $7
a
c
else
k
fi