MAINT-2242 Fix for shader compilation errors on Intel HD graphics chips.

1 files changed, 36 insertions, 3 deletions

diff --git a/indra/newview/app_settings/shaders/class1/objects/previewV.glsl b/indra/newview/app_settings/shaders/class1/objects/previewV.glsl
index da3387e7a5..7f3f84398b 100644
--- a/indra/newview/app_settings/shaders/class1/objects/previewV.glsl
+++ b/indra/newview/app_settings/shaders/class1/objects/previewV.glsl
@@ -23,9 +23,6 @@
  * $/LicenseInfo$
  */
 
-float calcDirectionalLight(vec3 n, vec3 l);
-float calcPointLightOrSpotLight(vec3 v, vec3 n, vec4 lp, vec3 ln, float la, float is_pointlight);
-
 uniform mat3 normal_matrix;
 uniform mat4 texture_matrix0;
 uniform mat4 modelview_matrix;
@@ -45,6 +42,42 @@ uniform vec3 light_direction[8];
 uniform vec3 light_attenuation[8]; 
 uniform vec3 light_diffuse[8];
 
+//===================================================================================================
+//declare these here explicitly to separate them from atmospheric lighting elsewhere to work around
+//drivers that are picky about functions being declared but not defined even if they aren't called
+float calcDirectionalLight(vec3 n, vec3 l)
+{
+	float a = max(dot(n,l),0.0);
+	return a;
+}
+
+
+float calcPointLightOrSpotLight(vec3 v, vec3 n, vec4 lp, vec3 ln, float la, float is_pointlight)
+{
+	//get light vector
+	vec3 lv = lp.xyz-v;
+	
+	//get distance
+	float d = length(lv);
+	
+	//normalize light vector
+	lv *= 1.0/d;
+	
+	//distance attenuation
+	float da = clamp(1.0/(la * d), 0.0, 1.0);
+	
+	// spotlight coefficient.
+	float spot = max(dot(-ln, lv), is_pointlight);
+	da *= spot*spot; // GL_SPOT_EXPONENT=2
+
+	//angular attenuation
+	da *= calcDirectionalLight(n, lv);
+
+	return da;	
+}
+//====================================================================================================
+
+
 void main()
 {
 	//transform vertex