diff --git a/polymer/eduke32/source/lunatic/engine.lua b/polymer/eduke32/source/lunatic/engine.lua
index baf9b4f63..c09c26bf8 100644
--- a/polymer/eduke32/source/lunatic/engine.lua
+++ b/polymer/eduke32/source/lunatic/engine.lua
@@ -202,8 +202,8 @@ end
 
 
 local function check_colcomp(a)
-    if (type(a) ~= "number" or not (a >= 0 and a <= 63)) then
-        error("color component must be in the range [0 .. 63]", 3)
+    if (type(a) ~= "number" or not (a >= 0 and a < 64)) then
+        error("color component must be in the range [0 .. 64)", 3)
     end
 end
 
diff --git a/polymer/eduke32/source/lunatic/test/shadexfog.lua b/polymer/eduke32/source/lunatic/test/shadexfog.lua
index 26dfe410d..15aae6709 100644
--- a/polymer/eduke32/source/lunatic/test/shadexfog.lua
+++ b/polymer/eduke32/source/lunatic/test/shadexfog.lua
@@ -340,7 +340,9 @@ end
 -- shadexfog.create_trans(startblendidx, func [, numtables [, fullbrightsOK]])
 --
 -- <func>: must be
---  rr, gg, bb = f(r, g, b, R, G, B, level, numtables)
+--  rr, gg, bb = f(r,g,b, R,G,B, level, numtables)
+--  If reverse translucency bit clear, (r,g,b) is background and (R,G,B) is
+--  foreground (incoming).
 --  ('level' is the table index, from 1 to <numtables>)
 -- <numtables>: number of tables to create, from <startblendidx> on. Default: 1
 function shadexfog.create_trans(startblendidx, func, numtables, fullbrightsOK)
@@ -411,6 +413,22 @@ function shadexfog.create_additive_trans(startblendidx, numtables, fullbrightsOK
     )
 end
 
+-- shadexfog.create_brightpass_trans(startblendidx [, numtables [, fullbrightsOK]])
+function shadexfog.create_brightpass_trans(startblendidx, numtables, fullbrightsOK)
+    shadexfog.create_trans(
+        startblendidx,
+
+        function(r,g,b, R,G,B, alpha, numtabs)
+            local a = alpha/numtabs
+            local F = 1 - min(a, (R+G+B) / (3*63))
+            local f = 1 - F
+            return f*r+F*R, f*g+F*G, f*b+F*B
+        end,
+
+        numtables, fullbrightsOK
+    )
+end
+
 if (not ismapster32) then
     return shadexfog
 end
@@ -589,6 +607,30 @@ starting with the blending number <startbl>, with fractions
 ]=]
 )
 
+engine.registerMenuFunc(
+    "Create bri.pass tr. tabs",
+    CreateMenuFunction{
+        [0] = shadexfog.create_brightpass_trans,
+        { "Starting blendnum", 1, 255 },
+        { "Number of blending tables", 32, 255 },
+        { "Fullbright result colors OK?", 0, 1, GNF_BOOL },
+    },
+
+formatHelp
+[=[
+<shadexfog.create_brightpass_trans(startbl [, numtabs [, fullbriOK]])>
+<____________________________________________________________________>
+
+Creates <numtabs> blending tables of "brightpass" translucency,
+starting with the blending number <startbl>, with fractions
+
+  1/<numtables>, 2/<numtables> ... <numtables>/<numtables>.
+
+ <fullbriOK>: should fullbright color indices (>= 240) be permitted as
+            the blending result of two color indices?
+]=]
+)
+
 engine.registerMenuFunc(
     "Create base shade table",
     CreateMenuFunction{