diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index da290ec47f..da8965454a 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -226,17 +226,87 @@ UINT8 HWR_FogBlockAlpha(INT32 light, extracolormap_t *colormap) // Let's see if
 	return surfcolor.s.alpha;
 }
 
-static FUINT HWR_CalcWallLight(FUINT lightnum, fixed_t v1x, fixed_t v1y, fixed_t v2x, fixed_t v2y)  // TODO: improve "fake contrast" system
+static FUINT HWR_CalcWallLight(FUINT lightnum, fixed_t v1x, fixed_t v1y, fixed_t v2x, fixed_t v2y)
 {
 	INT16 finallight = lightnum;
-	const UINT8 contrast = 8;
 
-	if (v1y == v2y)
-		finallight -= contrast;
-	else if (v1x == v2x)
-		finallight += contrast;
+	if (cv_glfakecontrast.value != 0)
+	{
+		const UINT8 contrast = 8;
+		fixed_t extralight = 0;
+
+		if (cv_glfakecontrast.value == 2) // Smooth setting
+		{
+			extralight = (-(contrast<<FRACBITS) +
+			FixedDiv(AngleFixed(R_PointToAngle2(0, 0,
+				abs(v1x - v2x),
+				abs(v1y - v2y))), 90<<FRACBITS)
+			* (contrast * 2)) >> FRACBITS;
+		}
+		else
+		{
+			if (v1y == v2y)
+				extralight = -contrast;
+			else if (v1x == v2x)
+				extralight = contrast;
+		}
+
+		if (extralight != 0)
+		{
+			finallight += extralight;
 
-	return (FUINT)max(0, min(255, finallight));
+			if (finallight < 0)
+				finallight = 0;
+			if (finallight > 255)
+				finallight = 255;
+		}
+	}
+
+	return (FUINT)finallight;
+}
+
+static FUINT HWR_CalcSlopeLight(FUINT lightnum, angle_t dir, fixed_t delta)
+{
+	INT16 finallight = lightnum;
+
+	if (cv_glfakecontrast.value != 0 && cv_glslopecontrast.value != 0)
+	{
+		const UINT8 contrast = 8;
+		fixed_t extralight = 0;
+
+		if (cv_glfakecontrast.value == 2) // Smooth setting
+		{
+			fixed_t dirmul = abs(FixedDiv(AngleFixed(dir) - (180<<FRACBITS), 180<<FRACBITS));
+
+			extralight = -(contrast<<FRACBITS) + (dirmul * (contrast * 2));
+
+			extralight = FixedMul(extralight, delta*4) >> FRACBITS;
+		}
+		else
+		{
+			dir = ((dir + ANGLE_45) / ANGLE_90) * ANGLE_90;
+
+			if (dir == ANGLE_180)
+				extralight = -contrast;
+			else if (dir == 0)
+				extralight = contrast;
+
+			if (delta >= FRACUNIT/2)
+				extralight *= 2;
+		}
+
+		if (extralight != 0)
+		{
+			finallight += extralight;
+
+			if (finallight < 0)
+				finallight = 0;
+			if (finallight > 255)
+				finallight = 255;
+		}
+	}
+
+	return (FUINT)finallight;
 }
 
 static UINT8 HWR_SideLightLevel(side_t *side, INT16 base_lightlevel)
@@ -428,6 +498,9 @@ static void HWR_RenderPlane(subsector_t *subsector, extrasubsector_t *xsub, bool
 	for (i = 0, v3d = planeVerts; i < (INT32)nrPlaneVerts; i++,v3d++,pv++)
 		SETUP3DVERT(v3d, pv->x, pv->y);
 
+	if (slope)
+		lightlevel = HWR_CalcSlopeLight(lightlevel, R_PointToAngle2(0, 0, slope->normal.x, slope->normal.y), abs(slope->zdelta));
+
 	HWR_Lighting(&Surf, lightlevel, planecolormap);
 
 	if (PolyFlags & (PF_Translucent|PF_Fog|PF_Additive|PF_Subtractive|PF_ReverseSubtract|PF_Multiplicative|PF_Environment))
@@ -5603,6 +5676,7 @@ void HWR_LoadLevel(void)
 
 static CV_PossibleValue_t glshaders_cons_t[] = {{0, "Off"}, {1, "On"}, {2, "Ignore custom shaders"}, {0, NULL}};
 static CV_PossibleValue_t glmodelinterpolation_cons_t[] = {{0, "Off"}, {1, "Sometimes"}, {2, "Always"}, {0, NULL}};
+static CV_PossibleValue_t glfakecontrast_cons_t[] = {{0, "Off"}, {1, "On"}, {2, "Smooth"}, {0, NULL}};
 static CV_PossibleValue_t glshearing_cons_t[] = {{0, "Off"}, {1, "On"}, {2, "Third-person"}, {0, NULL}};
 
 static void CV_glfiltermode_OnChange(void);
@@ -5636,6 +5710,8 @@ consvar_t cv_glmodellighting = CVAR_INIT ("gr_modellighting", "Off", CV_SAVE|CV_
 consvar_t cv_glshearing = CVAR_INIT ("gr_shearing", "Off", CV_SAVE, glshearing_cons_t, NULL);
 consvar_t cv_glspritebillboarding = CVAR_INIT ("gr_spritebillboarding", "Off", CV_SAVE, CV_OnOff, NULL);
 consvar_t cv_glskydome = CVAR_INIT ("gr_skydome", "On", CV_SAVE, CV_OnOff, NULL);
+consvar_t cv_glfakecontrast = CVAR_INIT ("gr_fakecontrast", "Smooth", CV_SAVE, glfakecontrast_cons_t, NULL);
+consvar_t cv_glslopecontrast = CVAR_INIT ("gr_slopecontrast", "Off", CV_SAVE, CV_OnOff, NULL);
 
 consvar_t cv_glfiltermode = CVAR_INIT ("gr_filtermode", "Nearest", CV_SAVE|CV_CALL, glfiltermode_cons_t, CV_glfiltermode_OnChange);
 consvar_t cv_glanisotropicmode = CVAR_INIT ("gr_anisotropicmode", "1", CV_SAVE|CV_CALL, glanisotropicmode_cons_t, CV_glanisotropic_OnChange);
@@ -5717,6 +5793,7 @@ void HWR_AddCommands(void)
 
 	CV_RegisterVar(&cv_glskydome);
 	CV_RegisterVar(&cv_glspritebillboarding);
+	CV_RegisterVar(&cv_glfakecontrast);
 	CV_RegisterVar(&cv_glshearing);
 	CV_RegisterVar(&cv_glshaders);
 
diff --git a/src/hardware/hw_main.h b/src/hardware/hw_main.h
index 8faa1f6929..2277c32f3c 100644
--- a/src/hardware/hw_main.h
+++ b/src/hardware/hw_main.h
@@ -91,6 +91,8 @@ extern consvar_t cv_glsolvetjoin;
 extern consvar_t cv_glshearing;
 extern consvar_t cv_glspritebillboarding;
 extern consvar_t cv_glskydome;
+extern consvar_t cv_glfakecontrast;
+extern consvar_t cv_glslopecontrast;
 extern consvar_t cv_glbatching;
 extern consvar_t cv_glpaletterendering;
 extern consvar_t cv_glpalettedepth;