diff --git a/code/renderergl2/glsl/lightall_fp.glsl b/code/renderergl2/glsl/lightall_fp.glsl
index 6a0a5155..8edbebda 100644
--- a/code/renderergl2/glsl/lightall_fp.glsl
+++ b/code/renderergl2/glsl/lightall_fp.glsl
@@ -332,19 +332,29 @@ void main()
 	// diffuse rgb is base color
 	// specular red is smoothness
 	// specular green is metallicness
-	float roughness = 1.0 - specular.r;
+	float gloss = specular.r;
 	specular.rgb = specular.g * diffuse.rgb + vec3(0.04 - 0.04 * specular.g);
 	diffuse.rgb *= 1.0 - specular.g;
   #else
 	// diffuse rgb is diffuse
 	// specular rgb is specular reflectance at normal incidence
 	// specular alpha is gloss
-	float roughness = exp2(-3.0 * specular.a);
+	float gloss = specular.a;
 
 	// adjust diffuse by specular reflectance, to maintain energy conservation
 	diffuse.rgb *= vec3(1.0) - specular.rgb;
   #endif
 
+  #if defined(GLOSS_IS_GLOSS)
+	float roughness = exp2(-3.0 * gloss);
+  #elif defined(GLOSS_IS_SMOOTHNESS)
+	float roughness = 1.0 - gloss;
+  #elif defined(GLOSS_IS_ROUGHNESS)
+	float roughness = gloss;
+  #elif defined(GLOSS_IS_SHININESS)
+	float roughness = pow(2.0 / (8190.0 * gloss + 2.0), 0.25);
+  #endif
+
 	reflectance  = CalcDiffuse(diffuse.rgb, NH, EH, roughness);
 
 	gl_FragColor.rgb  = lightColor   * reflectance * (attenuation * NL);
diff --git a/code/renderergl2/tr_glsl.c b/code/renderergl2/tr_glsl.c
index f8637a66..b825c19e 100644
--- a/code/renderergl2/tr_glsl.c
+++ b/code/renderergl2/tr_glsl.c
@@ -1057,6 +1057,23 @@ void GLSL_InitGPUShaders(void)
 
 			if (r_cubeMapping->integer)
 				Q_strcat(extradefines, 1024, "#define USE_CUBEMAP\n");
+
+			switch (r_glossType->integer)
+			{
+				case 0:
+				default:
+					Q_strcat(extradefines, 1024, "#define GLOSS_IS_GLOSS\n");
+					break;
+				case 1:
+					Q_strcat(extradefines, 1024, "#define GLOSS_IS_SMOOTHNESS\n");
+					break;
+				case 2:
+					Q_strcat(extradefines, 1024, "#define GLOSS_IS_ROUGHNESS\n");
+					break;
+				case 3:
+					Q_strcat(extradefines, 1024, "#define GLOSS_IS_SHININESS\n");
+					break;
+			}
 		}
 
 		if (i & LIGHTDEF_USE_SHADOWMAP)
diff --git a/code/renderergl2/tr_init.c b/code/renderergl2/tr_init.c
index 91110758..05cd40e7 100644
--- a/code/renderergl2/tr_init.c
+++ b/code/renderergl2/tr_init.c
@@ -147,6 +147,7 @@ cvar_t  *r_baseNormalY;
 cvar_t  *r_baseParallax;
 cvar_t  *r_baseSpecular;
 cvar_t  *r_baseGloss;
+cvar_t  *r_glossType;
 cvar_t  *r_mergeLightmaps;
 cvar_t  *r_dlightMode;
 cvar_t  *r_pshadowDist;
@@ -1236,6 +1237,7 @@ void R_Register( void )
 	r_baseParallax = ri.Cvar_Get( "r_baseParallax", "0.05", CVAR_ARCHIVE | CVAR_LATCH );
 	r_baseSpecular = ri.Cvar_Get( "r_baseSpecular", "0.04", CVAR_ARCHIVE | CVAR_LATCH );
 	r_baseGloss = ri.Cvar_Get( "r_baseGloss", "0.3", CVAR_ARCHIVE | CVAR_LATCH );
+	r_glossType = ri.Cvar_Get("r_glossType", "1", CVAR_ARCHIVE | CVAR_LATCH);
 	r_dlightMode = ri.Cvar_Get( "r_dlightMode", "0", CVAR_ARCHIVE | CVAR_LATCH );
 	r_pshadowDist = ri.Cvar_Get( "r_pshadowDist", "128", CVAR_ARCHIVE );
 	r_mergeLightmaps = ri.Cvar_Get( "r_mergeLightmaps", "1", CVAR_ARCHIVE | CVAR_LATCH );
diff --git a/code/renderergl2/tr_local.h b/code/renderergl2/tr_local.h
index b139cba2..78e37ecb 100644
--- a/code/renderergl2/tr_local.h
+++ b/code/renderergl2/tr_local.h
@@ -1794,6 +1794,7 @@ extern  cvar_t  *r_baseNormalY;
 extern  cvar_t  *r_baseParallax;
 extern  cvar_t  *r_baseSpecular;
 extern  cvar_t  *r_baseGloss;
+extern  cvar_t  *r_glossType;
 extern  cvar_t  *r_dlightMode;
 extern  cvar_t  *r_pshadowDist;
 extern  cvar_t  *r_mergeLightmaps;