glsl: fix heightmap orientation, black is low and white is high

there is only one heightmap standard: black is
low and white is high

xreal was doing white is low and black is high
for heightmap in alpha channel of normal map
but was doing black is low and white is high
for heightmap in loose file which does not
make sense

in any way daemon seems to have been forked
before the addition of shader keywords to
support heightmap loose file so only heightmap
in alpha channel is supported at this point

src/engine/renderer/glsl_source/forwardLighting_fp.glsl

@@ -965,7 +965,7 @@ void	main()
 	Vts = normalize(Vts);
 
 	// size and start position of search in texture space
-	vec2 S = Vts.xy * -u_DepthScale / Vts.z;
+	vec2 S = Vts.xy * u_DepthScale / Vts.z;
 
 	float depth = RayIntersectDisplaceMap(texNormal, S, u_NormalMap);
 

src/engine/renderer/glsl_source/lightMapping_fp.glsl

@@ -63,7 +63,7 @@ void	main()
 	V = normalize(V);
 
 	// size and start position of search in texture space
-	vec2 S = V.xy * -u_DepthScale / V.z;
+	vec2 S = V.xy * u_DepthScale / V.z;
 
 #if 0
 	vec2 texOffset = vec2(0.0);

src/engine/renderer/glsl_source/liquid_fp.glsl

@@ -155,8 +155,8 @@ void	main()
 	// ray intersect in view direction
 
 	// size and start position of search in texture space
-	//vec2 S = V.xy * -u_DepthScale / V.z;
-	vec2 S = V.xy * -0.03 / V.z;
+	//vec2 S = V.xy * u_DepthScale / V.z;
+	vec2 S = V.xy * 0.03 / V.z;
 
 	float depth = RayIntersectDisplaceMap(texNormal, S);
 

src/engine/renderer/glsl_source/vertexLighting_DBS_entity_fp.glsl

@@ -100,7 +100,7 @@ void	main()
 	Vts = normalize(Vts);
 
 	// size and start position of search in texture space
-	vec2 S = Vts.xy * -u_DepthScale / Vts.z;
+	vec2 S = Vts.xy * u_DepthScale / Vts.z;
 
 #if 0
 	vec2 texOffset = vec2(0.0);

src/engine/renderer/glsl_source/vertexLighting_DBS_world_fp.glsl

@@ -94,7 +94,7 @@ void	main()
 	Vts = normalize(Vts);
 
 	// size and start position of search in texture space
-	vec2 S = Vts.xy * -u_DepthScale / Vts.z;
+	vec2 S = Vts.xy * u_DepthScale / Vts.z;
 
 #if 0
 	vec2 texOffset = vec2(0.0);