diff --git a/wadsrc/static/shaders/glsl/main.vp b/wadsrc/static/shaders/glsl/main.vp
index cea479f3b..44aec6199 100644
--- a/wadsrc/static/shaders/glsl/main.vp
+++ b/wadsrc/static/shaders/glsl/main.vp
@@ -50,16 +50,18 @@ void main()
 	
 	gl_Position = ProjectionMatrix * eyeCoordPos;
 	
-	// clip planes used for reflective flats
-	if (uClipHeightBottom  > -65536.0)
-	{
-		gl_ClipDistance[0] = worldcoord.y - uClipHeightBottom;
-	}
-	else if (uClipHeightTop < 65536.0)
-	{
-		gl_ClipDistance[0] = uClipHeightTop - worldcoord.y;
-	}
+    #if defined __GLSL_CG_DATA_TYPES && defined GLSL12_COMPATIBILE
+		gl_ClipVertex = eyeCoordPos;
+	#endif
 	
+	
+	// clip planes used for reflective flats
+	if (uClipHeightDirection != 0.0)
+	{
+		gl_ClipDistance[0] = (worldcoord.y - uClipHeight) * uClipHeightDirection;
+	}
+
+	// clip planes used for translucency splitting
 	gl_ClipDistance[1] = worldcoord.y - uClipSplit.x;
 	gl_ClipDistance[2] = uClipSplit.y - worldcoord.y;
 	
diff --git a/wadsrc/static/shaders/glsl/shaderdefs.i b/wadsrc/static/shaders/glsl/shaderdefs.i
index d49034973..5259bb5fd 100644
--- a/wadsrc/static/shaders/glsl/shaderdefs.i
+++ b/wadsrc/static/shaders/glsl/shaderdefs.i
@@ -6,7 +6,7 @@ precision highp float;
 
 uniform vec4 uCameraPos;
 uniform int uTextureMode;
-uniform float uClipHeightTop, uClipHeightBottom;
+uniform float uClipHeight, uClipHeightDirection;
 uniform vec2 uClipSplit;
 
 uniform float uAlphaThreshold;