Fixed so that we could use DTX5nm as normal map

resources/Shaders/Util/CommonNormalFunc.glsl

@@ -0,0 +1,21 @@
+#define NORMAL_DDS 1
+#define NORMAL_PNG 2
+
+vec3 NormalMapValue(vec2 textureCoordinate, sampler2D normalMap, int normalTextureType){
+	if(normalTextureType == NORMAL_DDS){
+		vec3 normal;
+		normal.xy = texture(normalMap, textureCoordinate).wy * 2.0 - vec2(1.0);
+		normal.z = sqrt(1.0 -  clamp(dot(normal.xy, normal.xy), 0.0, 1.0));
+		return normal;
+	} else {
+		//should be PNG or anything that doesn't need special support
+		return texture(normalMap, textureCoordinate).xyz * 2.0 - vec3(1.0);
+	}
+}
+
+vec4 CalcNormalMappedValue(vec3 normal, vec3 tangent, vec3 bitangent, vec2 textureCoordinate, sampler2D normalMap, int normalTextureType)
+{
+	mat3 TBN = mat3(tangent, bitangent, normal);
+	vec3 NormalMap = NormalMapValue(textureCoordinate, normalMap, normalTextureType);
+	return vec4(TBN * normalize(NormalMap), 0.0);
+}