ref: gl: support kRenderFxLightMultiplier

* add undocumented kRenderFxLightMultiplier to const.h

common/const.h

@@ -717,6 +717,7 @@ enum
 	kRenderFxExplode,			// Scale up really big!
 	kRenderFxGlowShell,			// Glowing Shell
 	kRenderFxClampMinScale,		// Keep this sprite from getting very small (SPRITES only!)
+	kRenderFxLightMultiplier,
 };
 
 typedef int		func_t;

ref/gl/gl_studio.c

@@ -1435,6 +1435,13 @@ void R_StudioDynamicLight( cl_entity_t *ent, alight_t *plight )
 		}
 	}
 
+	if( ent->curstate.renderfx == kRenderFxLightMultiplier && ent->curstate.iuser4 != 10 )
+	{
+		light.r *= ent->curstate.iuser4 / 10.0f;
+		light.g *= ent->curstate.iuser4 / 10.0f;
+		light.b *= ent->curstate.iuser4 / 10.0f;
+	}
+
 	VectorSet( finalLight, light.r, light.g, light.b );
 	ent->cvFloorColor = light;