Merge remote-tracking branch 'origin/DRTVWR-528' into DRTVWR-559

20 files changed, 409 insertions, 297 deletions

diff --git a/indra/newview/app_settings/shaders/class1/deferred/avatarAlphaNoColorV.glsl b/indra/newview/app_settings/shaders/class1/deferred/avatarAlphaNoColorV.glsl
deleted file mode 100644
index bbdc8fdd1c..0000000000
--- a/indra/newview/app_settings/shaders/class1/deferred/avatarAlphaNoColorV.glsl
+++ /dev/null
@@ -1,112 +0,0 @@
-/** 
- * @file avatarAlphaNoColorV.glsl
- *
- * $LicenseInfo:firstyear=2007&license=viewerlgpl$
- * Second Life Viewer Source Code
- * Copyright (C) 2007, Linden Research, Inc.
- * 
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation;
- * version 2.1 of the License only.
- * 
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- * 
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- * 
- * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
- * $/LicenseInfo$
- */
-
-uniform mat4 projection_matrix;
-
-ATTRIBUTE vec3 position;
-ATTRIBUTE vec3 normal;
-ATTRIBUTE vec2 texcoord0;
-
-mat4 getSkinnedTransform();
-void calcAtmospherics(vec3 inPositionEye);
-
-float calcDirectionalLight(vec3 n, vec3 l);
-
-vec3 atmosAmbient();
-vec3 atmosAffectDirectionalLight(float lightIntensity);
-
-VARYING vec3 vary_position;
-VARYING vec3 vary_ambient;
-VARYING vec3 vary_directional;
-VARYING vec3 vary_fragcoord;
-VARYING vec3 vary_pointlight_col;
-VARYING vec2 vary_texcoord0;
-VARYING vec3 vary_norm;
-
-
-uniform float near_clip;
-
-uniform vec4 color;
-
-uniform vec4 light_position[8];
-uniform vec3 light_direction[8];
-uniform vec3 light_attenuation[8]; 
-uniform vec3 light_diffuse[8];
-
-float calcPointLightOrSpotLight(vec3 v, vec3 n, vec4 lp, vec3 ln, float la, float fa, float is_pointlight);
-
-void main()
-{
-	vary_texcoord0 = texcoord0;
-				
-	vec4 pos;
-	vec3 norm;
-	
-	mat4 trans = getSkinnedTransform();
-	vec4 pos_in = vec4(position.xyz, 1.0);
-	pos.x = dot(trans[0], pos_in);
-	pos.y = dot(trans[1], pos_in);
-	pos.z = dot(trans[2], pos_in);
-	pos.w = 1.0;
-	
-	norm.x = dot(trans[0].xyz, normal);
-	norm.y = dot(trans[1].xyz, normal);
-	norm.z = dot(trans[2].xyz, normal);
-	norm = normalize(norm);
-	vary_norm = norm;
-		
-	vec4 frag_pos = projection_matrix * pos;
-	gl_Position = frag_pos;
-	
-	vary_position = pos.xyz;
-	
-	calcAtmospherics(pos.xyz);
-
-	vec4 col = vec4(0.0, 0.0, 0.0, 1.0);
-
-	// Collect normal lights
-	col.rgb += light_diffuse[2].rgb*calcPointLightOrSpotLight(pos.xyz, norm, light_position[2], light_direction[2], light_attenuation[2].x, light_attenuation[2].y, light_attenuation[2].z);
-	col.rgb += light_diffuse[3].rgb*calcPointLightOrSpotLight(pos.xyz, norm, light_position[3], light_direction[3], light_attenuation[3].x, light_attenuation[3].y, light_attenuation[3].z);
-	col.rgb += light_diffuse[4].rgb*calcPointLightOrSpotLight(pos.xyz, norm, light_position[4], light_direction[4], light_attenuation[4].x, light_attenuation[4].y, light_attenuation[4].z);
-	col.rgb += light_diffuse[5].rgb*calcPointLightOrSpotLight(pos.xyz, norm, light_position[5], light_direction[5], light_attenuation[5].x, light_attenuation[5].y, light_attenuation[5].z);
-	col.rgb += light_diffuse[6].rgb*calcPointLightOrSpotLight(pos.xyz, norm, light_position[6], light_direction[6], light_attenuation[6].x, light_attenuation[6].y, light_attenuation[6].z);
-	col.rgb += light_diffuse[7].rgb*calcPointLightOrSpotLight(pos.xyz, norm, light_position[7], light_direction[7], light_attenuation[7].x, light_attenuation[7].y, light_attenuation[7].z);
-	
-	vary_pointlight_col = col.rgb*color.rgb;
-
-	col.rgb = vec3(0,0,0);
-
-	// Add windlight lights
-	col.rgb = atmosAmbient();
-	
-	vary_ambient = col.rgb*color.rgb;
-	vary_directional = color.rgb*atmosAffectDirectionalLight(max(calcDirectionalLight(norm, light_position[0].xyz), 0.0));
-	
-	col.rgb = col.rgb * color.rgb;
-	
-	vary_fragcoord.xyz = frag_pos.xyz + vec3(0,0,near_clip);
-}
-
-
diff --git a/indra/newview/app_settings/shaders/class1/deferred/cloudsF.glsl b/indra/newview/app_settings/shaders/class1/deferred/cloudsF.glsl
index 788ce4a47b..b45dfcd550 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/cloudsF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/cloudsF.glsl
@@ -126,6 +126,6 @@ void main()
     frag_data[1] = vec4(0.0,0.0,0.0,0.0);
     frag_data[2] = vec4(0,0,0,GBUFFER_FLAG_SKIP_ATMOS);
 
-    gl_FragDepth = 0.99995f;
+    gl_FragDepth = LL_SHADER_CONST_CLOUD_MOON_DEPTH; // SL-14113 Stars and Clouds need same depth
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/moonF.glsl b/indra/newview/app_settings/shaders/class1/deferred/moonF.glsl
index b4044353b4..7032c45603 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/moonF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/moonF.glsl
@@ -54,6 +54,12 @@ void main()
         fade = clamp( moon_dir.z*moon_dir.z*4.0, 0.0, 1.0 );
 
     vec4 c      = texture2D(diffuseMap, vary_texcoord0.xy);
+
+    // SL-14113 Don't write to depth; prevent moon's quad from hiding stars which should be visible
+    // Moon texture has transparent pixels <0x55,0x55,0x55,0x00>
+    if (c.a <= 2./255.) // 0.00784
+        discard;
+
 //       c.rgb  = srgb_to_linear(c.rgb);
          c.rgb *= moonlight_color.rgb;
          c.rgb *= moon_brightness;
@@ -67,6 +73,6 @@ void main()
     frag_data[1] = vec4(0.0);
     frag_data[2] = vec4(0.0, 0.0, 0.0, GBUFFER_FLAG_HAS_ATMOS);
 
-    gl_FragDepth = 0.999985f;
+    gl_FragDepth = LL_SHADER_CONST_CLOUD_MOON_DEPTH; // SL-14113
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/starsF.glsl b/indra/newview/app_settings/shaders/class1/deferred/starsF.glsl
index ef9cee3fa0..6376527273 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/starsF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/starsF.glsl
@@ -46,8 +46,13 @@ float twinkle(){
     return abs(d);
 }
 
+// See:
+// ALM off: class1/environment/starsF.glsl
+// ALM on : class1/deferred/starsF.glsl
 void main() 
 {
+	// camera above water: class1\deferred\starsF.glsl
+	// camera below water: class1\environment\starsF.glsl
     vec4 col_a = texture2D(diffuseMap, vary_texcoord0.xy);
     vec4 col_b = texture2D(diffuseMap, vary_texcoord0.xy);
     vec4 col = mix(col_b, col_a, blend_factor);
@@ -62,6 +67,6 @@ void main()
     frag_data[1] = vec4(0.0f);
     frag_data[2] = vec4(0.0, 1.0, 0.0, GBUFFER_FLAG_SKIP_ATMOS);
 
-    gl_FragDepth = 0.99995f;
+    gl_FragDepth = LL_SHADER_CONST_STAR_DEPTH; // SL-14113 Moon Haze -- Stars need to depth test behind the moon
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/waterV.glsl b/indra/newview/app_settings/shaders/class1/deferred/waterV.glsl
index 8863869e44..38276859a0 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/waterV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/waterV.glsl
@@ -70,7 +70,7 @@ void main()
 	d *= d;
 		
 	oPosition = vec4(position, 1.0);
-	oPosition.z = mix(oPosition.z, max(eyeVec.z*0.75, 0.0), d);
+//	oPosition.z = mix(oPosition.z, max(eyeVec.z*0.75, 0.0), d); // SL-11589 remove "U" shaped horizon
 	vary_position = modelview_matrix * oPosition;
 	oPosition = modelViewProj * oPosition;
 	
diff --git a/indra/newview/app_settings/shaders/class1/environment/moonF.glsl b/indra/newview/app_settings/shaders/class1/environment/moonF.glsl
new file mode 100644
index 0000000000..a220971f06
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/environment/moonF.glsl
@@ -0,0 +1,51 @@
+/** 
+ * @file class1/environment/moonF.glsl
+ *
+ * $LicenseInfo:firstyear=2021&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2021, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#ifdef DEFINE_GL_FRAGCOLOR
+out vec4 frag_color;
+#else
+#define frag_color gl_FragColor
+#endif
+
+uniform sampler2D tex0;
+
+VARYING vec2 vary_texcoord0;
+
+// See:
+// AS  off: class1/environment/moonF.glsl
+// ALM off: class1/windlight/moonF.glsl
+// ALM on : class1/deferred/moonF.glsl
+void main() 
+{
+    vec4 color = texture2D(tex0, vary_texcoord0.xy);
+
+    // SL-14113 Don't write to depth; prevent moon's quad from hiding stars which should be visible
+    // Moon texture has transparent pixels <0x55,0x55,0x55,0x00>
+    if (color.a <= 2./255.) // 0.00784
+        discard;
+
+    frag_color = color;
+    gl_FragDepth = LL_SHADER_CONST_CLOUD_MOON_DEPTH; // SL-14113 Moon is infront of stars
+}
diff --git a/indra/newview/app_settings/shaders/class1/objects/indexedTextureF.glsl b/indra/newview/app_settings/shaders/class1/environment/moonV.glsl
index 254c1d4fc2..75ad251fac 100644
--- a/indra/newview/app_settings/shaders/class1/objects/indexedTextureF.glsl
+++ b/indra/newview/app_settings/shaders/class1/environment/moonV.glsl
@@ -1,9 +1,9 @@
 /** 
- * @file fullbrightF.glsl
+ * @file class1\environment\moonV.glsl
  *
- * $LicenseInfo:firstyear=2007&license=viewerlgpl$
+ * $LicenseInfo:firstyear=2021&license=viewerlgpl$
  * Second Life Viewer Source Code
- * Copyright (C) 2007, Linden Research, Inc.
+ * Copyright (C) 2021, Linden Research, Inc.
  * 
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -22,12 +22,16 @@
  * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
  * $/LicenseInfo$
  */
- 
- 
 
+uniform mat4 modelview_projection_matrix;
 
-void main() 
+ATTRIBUTE vec3 position;
+
+VARYING vec2 vary_texcoord0;
+
+void main()
 {
-	fullbright_lighting();
+	gl_Position = modelview_projection_matrix * vec4(position, 1);
+	vary_texcoord0 = texcoord0;
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/shadowAlphaBlendF.glsl b/indra/newview/app_settings/shaders/class1/environment/starsF.glsl
index 44f2a73e1f..e1a9cc6387 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/shadowAlphaBlendF.glsl
+++ b/indra/newview/app_settings/shaders/class1/environment/starsF.glsl
@@ -1,9 +1,9 @@
 /** 
- * @file shadowAlphaMaskF.glsl
+ * @file class1/environment/starsF.glsl
  *
- * $LicenseInfo:firstyear=2011&license=viewerlgpl$
+ * $LicenseInfo:firstyear=2021&license=viewerlgpl$
  * Second Life Viewer Source Code
- * Copyright (C) 2011, Linden Research, Inc.
+ * Copyright (C) 2021, Linden Research, Inc.
  * 
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -23,8 +23,6 @@
  * $/LicenseInfo$
  */
 
-/*[EXTRA_CODE_HERE]*/
-
 #ifdef DEFINE_GL_FRAGCOLOR
 out vec4 frag_color;
 #else
@@ -33,23 +31,21 @@ out vec4 frag_color;
 
 uniform sampler2D diffuseMap;
 
-#if !defined(DEPTH_CLAMP)
-VARYING float pos_zd2;
-#endif
-
-VARYING float pos_w;
+uniform float custom_alpha;
 
-VARYING float target_pos_x;
 VARYING vec4 vertex_color;
 VARYING vec2 vary_texcoord0;
 
+// See:
+// ALM off: class1/environment/starsF.glsl
+// ALM on : class1/deferred/starsF.glsl
 void main() 
 {
-	float alpha = diffuseLookup(vary_texcoord0.xy).a * vertex_color.a;
+    vec4 color = texture2D(diffuseMap, vary_texcoord0.xy);
+    color.rgb = pow(color.rgb, vec3(0.45));
+    color.rgb *= vertex_color.rgb;
+    color.a *= max(custom_alpha, vertex_color.a);
 
-	frag_color = vec4(alpha, alpha, alpha, 1);
-	
-#if !defined(DEPTH_CLAMP)
-	gl_FragDepth = max(pos_zd2/pos_w+0.5, 0.0);
-#endif
+    frag_color = color;
+    gl_FragDepth = LL_SHADER_CONST_STAR_DEPTH; // SL-14113 Moon Haze -- Stars need to depth test behind the moon
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/shadowAlphaBlendV.glsl b/indra/newview/app_settings/shaders/class1/environment/starsV.glsl
index f45c343066..6fcfec6b6a 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/shadowAlphaBlendV.glsl
+++ b/indra/newview/app_settings/shaders/class1/environment/starsV.glsl
@@ -1,9 +1,9 @@
 /** 
- * @file shadowAlphaMaskV.glsl
+ * @file class1/environment/starsV.glsl
  *
- * $LicenseInfo:firstyear=2011&license=viewerlgpl$
+ * $LicenseInfo:firstyear=2021&license=viewerlgpl$
  * Second Life Viewer Source Code
- * Copyright (C) 2011, Linden Research, Inc.
+ * Copyright (C) 2021, Linden Research, Inc.
  * 
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -23,45 +23,19 @@
  * $/LicenseInfo$
  */
 
-uniform mat4 texture_matrix0;
 uniform mat4 modelview_projection_matrix;
-uniform float shadow_target_width;
 
 ATTRIBUTE vec3 position;
 ATTRIBUTE vec4 diffuse_color;
 ATTRIBUTE vec2 texcoord0;
 
-#if !defined(DEPTH_CLAMP)
-VARYING float pos_zd2;
-#endif
-
-VARYING float pos_w;
-
-VARYING float target_pos_x;
 VARYING vec4 vertex_color;
 VARYING vec2 vary_texcoord0;
 
-void passTextureIndex();
-
 void main()
 {
-	//transform vertex
-	vec4 pre_pos = vec4(position.xyz, 1.0);
-	vec4 pos = modelview_projection_matrix * pre_pos;
-	target_pos_x = 0.5 * (shadow_target_width - 1.0) * pos.x;
-
-	pos_w = pos.w;
-
-#if !defined(DEPTH_CLAMP)
-	pos_zd2 = pos.z * 0.5;
-	
-	gl_Position = vec4(pos.x, pos.y, pos.w*0.5, pos.w);
-#else
-	gl_Position = pos;
-#endif
-	
-	passTextureIndex();
-
-	vary_texcoord0 = (texture_matrix0 * vec4(texcoord0,0,1)).xy;
+	gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0);
+	vary_texcoord0 = texcoord0;
 	vertex_color = diffuse_color;
 }
+
diff --git a/indra/newview/app_settings/shaders/class1/environment/waterV.glsl b/indra/newview/app_settings/shaders/class1/environment/waterV.glsl
index a0a0e7dfca..ac400aa2a6 100644
--- a/indra/newview/app_settings/shaders/class1/environment/waterV.glsl
+++ b/indra/newview/app_settings/shaders/class1/environment/waterV.glsl
@@ -80,7 +80,7 @@ void main()
 	d *= d;
 		
 	oPosition = vec4(position, 1.0);
-	oPosition.z = mix(oPosition.z, max(eyeVec.z*0.75, 0.0), d);
+//	oPosition.z = mix(oPosition.z, max(eyeVec.z*0.75, 0.0), d); // SL-11589 remove "U" shaped horizon
 
 	oPosition = modelViewProj * oPosition;
 	
diff --git a/indra/newview/app_settings/shaders/class1/windlight/moonF.glsl b/indra/newview/app_settings/shaders/class1/windlight/moonF.glsl
index f03003f5e1..c4ab0c95dc 100644
--- a/indra/newview/app_settings/shaders/class1/windlight/moonF.glsl
+++ b/indra/newview/app_settings/shaders/class1/windlight/moonF.glsl
@@ -51,6 +51,12 @@ void main()
         fade = clamp( moon_dir.z*moon_dir.z*4.0, 0.0, 1.0 );
 
     vec4 c     = texture2D(diffuseMap, vary_texcoord0.xy);
+
+    // SL-14113 Don't write to depth; prevent moon's quad from hiding stars which should be visible
+    // Moon texture has transparent pixels <0x55,0x55,0x55,0x00>
+    if (c.a <= 2./255.) // 0.00784
+        discard;
+
 //       c.rgb = pow(c.rgb, vec3(0.7f)); // can't use "srgb_to_linear(color.rgb)" as that is a deferred only function
          c.rgb *= moonlight_color.rgb;
          c.rgb *= moon_brightness;
@@ -61,5 +67,6 @@ void main()
          c.rgb  = scaleSoftClip(c.rgb);
 
     frag_color = vec4(c.rgb, c.a);
+    gl_FragDepth = LL_SHADER_CONST_CLOUD_MOON_DEPTH; // SL-14113
 }
 
diff --git a/indra/newview/app_settings/shaders/class2/windlight/cloudsF.glsl b/indra/newview/app_settings/shaders/class2/windlight/cloudsF.glsl
index 9c5a4903d0..6f4bdbde28 100644
--- a/indra/newview/app_settings/shaders/class2/windlight/cloudsF.glsl
+++ b/indra/newview/app_settings/shaders/class2/windlight/cloudsF.glsl
@@ -127,5 +127,11 @@ void main()
 
     /// Gamma correct for WL (soft clip effect).
     frag_color = vec4(color.rgb, alpha1);
+
+    // SL-14113 Moon Haze -- When the camera is underwater fix clouds clipping into moon
+    // camera above water: class1\deferred\cloudsF.glsl
+    // camera below water: class2\windlight\coudsV.glsl
+    // See: starsV.glsl, cloudsV.glsl, moonF.glsl
+    gl_FragDepth = LL_SHADER_CONST_CLOUD_MOON_DEPTH;
 }
 
diff --git a/indra/newview/llagentcamera.cpp b/indra/newview/llagentcamera.cpp
index 57a59d81c4..5de52c1daf 100644
--- a/indra/newview/llagentcamera.cpp
+++ b/indra/newview/llagentcamera.cpp
@@ -2043,6 +2043,13 @@ LLVector3d LLAgentCamera::getFocusOffsetInitial()
 
 F32 LLAgentCamera::getCameraMaxZoomDistance()
 {
+    // SL-14706 / SL-14885 TPV have relaxed camera constraints allowing you to mousewheeel zoom WAY out.
+    static LLCachedControl<bool> s_disable_camera_constraints(gSavedSettings, "DisableCameraConstraints", false);
+    if (s_disable_camera_constraints)
+    {
+        return (F32)INT_MAX;
+    }
+
     // Ignore "DisableCameraConstraints", we don't want to be out of draw range when we focus onto objects or avatars
     return llmin(MAX_CAMERA_DISTANCE_FROM_OBJECT,
                  mDrawDistance - 1, // convenience, don't hit draw limit when focusing on something
diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index 6e0bbb05ee..da57a3cb31 100644
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -572,7 +572,7 @@ static void settings_modify()
     LLPipeline::sRenderDeferred = TRUE; // FALSE is deprecated --  LLPipeline::sRenderBump&& gSavedSettings.getBOOL("RenderDeferred");
     LLRenderTarget::sUseFBO             = LLPipeline::sRenderDeferred;
     LLVOSurfacePatch::sLODFactor        = gSavedSettings.getF32("RenderTerrainLODFactor");
-    LLVOSurfacePatch::sLODFactor *= LLVOSurfacePatch::sLODFactor;  // square lod factor to get exponential range of [1,4]
+    LLVOSurfacePatch::sLODFactor *= LLVOSurfacePatch::sLODFactor; //square lod factor to get exponential range of [1,4]
     gDebugGL       = gDebugGLSession || gDebugSession;
     gDebugPipeline = gSavedSettings.getBOOL("RenderDebugPipeline");
 }
diff --git a/indra/newview/lldrawpoolsky.cpp b/indra/newview/lldrawpoolsky.cpp
index 55ebf03adc..dba400d095 100644
--- a/indra/newview/lldrawpoolsky.cpp
+++ b/indra/newview/lldrawpoolsky.cpp
@@ -112,20 +112,39 @@ void LLDrawPoolSky::renderSkyFace(U8 index)
 		return;
 	}
 
-    if (index < 6) // sky tex...interp
+    if (index < LLVOSky::FACE_SUN) // sky tex...interp
     {
         llassert(mSkyTex);
 	    mSkyTex[index].bindTexture(true); // bind the current tex
 
         face->renderIndexed();
     }
+    else // Moon
+    if (index == LLVOSky::FACE_MOON)
+    {
+        LLGLSPipelineDepthTestSkyBox gls_skybox(true, true); // SL-14113 Write depth for moon so stars can test if behind it
+
+        LLGLEnable blend(GL_BLEND);
+
+        // if (LLGLSLShader::sNoFixedFunction) // TODO: Necessary? is this always true? We already bailed on gPipeline.canUseWindLightShaders ... above
+        LLViewerTexture* tex = face->getTexture(LLRender::DIFFUSE_MAP);
+        if (tex)
+        {
+            gMoonProgram.bind(); // SL-14113 was gOneTextureNoColorProgram
+            gGL.getTexUnit(0)->bind(tex, true);
+            face->renderIndexed();
+        }
+    }
     else // heavenly body faces, no interp...
     {
+        LLGLSPipelineDepthTestSkyBox gls_skybox(true, false); // reset to previous
+
         LLGLEnable blend(GL_BLEND);
 
         LLViewerTexture* tex = face->getTexture(LLRender::DIFFUSE_MAP);
         if (tex)
         {
+            gOneTextureNoColorProgram.bind();
             gGL.getTexUnit(0)->bind(tex, true);
             face->renderIndexed();
         }
diff --git a/indra/newview/lldrawpoolwater.cpp b/indra/newview/lldrawpoolwater.cpp
index 3f39716449..21b2e56c7c 100644
--- a/indra/newview/lldrawpoolwater.cpp
+++ b/indra/newview/lldrawpoolwater.cpp
@@ -357,7 +357,7 @@ void LLDrawPoolWater::renderOpaqueLegacyWater()
 {
 #if 0
     LL_PROFILE_ZONE_SCOPED_CATEGORY_DRAWPOOL;
-    LLVOSky *voskyp = gSky.mVOSkyp;
+	LLVOSky *voskyp = gSky.mVOSkyp;
 
     if (voskyp == NULL)
     {
@@ -365,16 +365,16 @@ void LLDrawPoolWater::renderOpaqueLegacyWater()
     }
 
 	LLGLSLShader* shader = NULL;
-	if (LLPipeline::sUnderWaterRender)
-	{
-		shader = &gObjectSimpleNonIndexedTexGenWaterProgram;
-	}
-	else
-	{
-		shader = &gObjectSimpleNonIndexedTexGenProgram;
-	}
+		if (LLPipeline::sUnderWaterRender)
+		{
+			shader = &gObjectSimpleNonIndexedTexGenWaterProgram;
+		}
+		else
+		{
+			shader = &gObjectSimpleNonIndexedTexGenProgram;
+		}
 
-	shader->bind();
+		shader->bind();
 
 	stop_glerror();
 
@@ -508,9 +508,9 @@ void LLDrawPoolWater::renderWater()
     LLColor3 light_diffuse(0, 0, 0);
     F32      light_exp = 0.0f;
 
-    LLEnvironment &        environment     = LLEnvironment::instance();
-    LLSettingsWater::ptr_t pwater          = environment.getCurrentWater();
-    LLSettingsSky::ptr_t   psky            = environment.getCurrentSky();
+    LLEnvironment& environment = LLEnvironment::instance();
+    LLSettingsWater::ptr_t pwater = environment.getCurrentWater();
+    LLSettingsSky::ptr_t   psky   = environment.getCurrentSky();
     LLVector3              light_dir       = environment.getLightDirection();
     bool                   sun_up          = environment.getIsSunUp();
     bool                   moon_up         = environment.getIsMoonUp();
@@ -535,15 +535,15 @@ void LLDrawPoolWater::renderWater()
     F32 ground_proj_sq = light_dir.mV[0] * light_dir.mV[0] + light_dir.mV[1] * light_dir.mV[1];
     light_exp          = llmax(32.f, 256.f * powf(ground_proj_sq, 16.0f));
     if (0.f < light_diffuse.normalize())  // Normalizing a color? Puzzling...
-    {
+	{
         light_diffuse *= (1.5f + (6.f * ground_proj_sq));
     }
 
     // set up normal maps filtering
     for (auto norm_map : mWaterNormp)
-    {
+	    {
         if (norm_map) norm_map->setFilteringOption(has_normal_mips ? LLTexUnit::TFO_ANISOTROPIC : LLTexUnit::TFO_POINT);
-    }
+	    }
 
     LLColor4      specular(sun_up ? psky->getSunlightColor() : psky->getMoonlightColor());
     F32           phase_time = (F32) LLFrameTimer::getElapsedSeconds() * 0.5f;
@@ -570,51 +570,51 @@ void LLDrawPoolWater::renderWater()
         }
 
         gPipeline.bindDeferredShader(*shader);
-
+	
         // bind textures for water rendering
-        S32 reftex = shader->enableTexture(LLShaderMgr::WATER_REFTEX);
-        if (reftex > -1)
-        {
-            gGL.getTexUnit(reftex)->activate();
-            gGL.getTexUnit(reftex)->bind(&gPipeline.mWaterRef);
-            gGL.getTexUnit(0)->activate();
-        }
+	S32 reftex = shader->enableTexture(LLShaderMgr::WATER_REFTEX);
+	if (reftex > -1)
+	{
+		gGL.getTexUnit(reftex)->activate();
+		gGL.getTexUnit(reftex)->bind(&gPipeline.mWaterRef);
+		gGL.getTexUnit(0)->activate();
+	}	
 
-        // bind normal map
-        S32 bumpTex  = shader->enableTexture(LLViewerShaderMgr::BUMP_MAP);
-        S32 bumpTex2 = shader->enableTexture(LLViewerShaderMgr::BUMP_MAP2);
+	//bind normal map
+	S32 bumpTex  = shader->enableTexture(LLViewerShaderMgr::BUMP_MAP);
+    S32 bumpTex2 = shader->enableTexture(LLViewerShaderMgr::BUMP_MAP2);
 
-        LLViewerTexture *tex_a = mWaterNormp[0];
-        LLViewerTexture *tex_b = mWaterNormp[1];
+    LLViewerTexture* tex_a = mWaterNormp[0];
+    LLViewerTexture* tex_b = mWaterNormp[1];
 
         F32 blend_factor = pwater->getBlendFactor();
+	
+    gGL.getTexUnit(bumpTex)->unbind(LLTexUnit::TT_TEXTURE);
+    gGL.getTexUnit(bumpTex2)->unbind(LLTexUnit::TT_TEXTURE);
 
-        gGL.getTexUnit(bumpTex)->unbind(LLTexUnit::TT_TEXTURE);
-        gGL.getTexUnit(bumpTex2)->unbind(LLTexUnit::TT_TEXTURE);
-
-        if (tex_a && (!tex_b || (tex_a == tex_b)))
-        {
-            gGL.getTexUnit(bumpTex)->bind(tex_a);
-            blend_factor = 0;  // only one tex provided, no blending
-        }
-        else if (tex_b && !tex_a)
-        {
-            gGL.getTexUnit(bumpTex)->bind(tex_b);
-            blend_factor = 0;  // only one tex provided, no blending
-        }
-        else if (tex_b != tex_a)
-        {
-            gGL.getTexUnit(bumpTex)->bind(tex_a);
-            gGL.getTexUnit(bumpTex2)->bind(tex_b);
-        }
-
-        // bind reflection texture from RenderTarget
-        S32 screentex   = shader->enableTexture(LLShaderMgr::WATER_SCREENTEX);
+    if (tex_a && (!tex_b || (tex_a == tex_b)))
+    {
+		gGL.getTexUnit(bumpTex)->bind(tex_a);
+        blend_factor = 0; // only one tex provided, no blending
+    }
+    else if (tex_b && !tex_a)
+    {
+        gGL.getTexUnit(bumpTex)->bind(tex_b);
+        blend_factor = 0; // only one tex provided, no blending
+    }
+    else if (tex_b != tex_a)
+    {
+        gGL.getTexUnit(bumpTex)->bind(tex_a);
+        gGL.getTexUnit(bumpTex2)->bind(tex_b);
+    }
+	
+    // bind reflection texture from RenderTarget
+	S32 screentex = shader->enableTexture(LLShaderMgr::WATER_SCREENTEX);
         S32 screenDepth = shader->enableTexture(LLShaderMgr::WATER_SCREENDEPTH);
 
         F32 screenRes[] = {1.f / gGLViewport[2], 1.f / gGLViewport[3]};
-
-        S32 diffTex = shader->enableTexture(LLShaderMgr::DIFFUSE_MAP);
+		
+	S32 diffTex = shader->enableTexture(LLShaderMgr::DIFFUSE_MAP);
 
         // set uniforms for shader
         if (deferred_render)
@@ -626,26 +626,26 @@ void LLDrawPoolWater::renderWater()
             }
         }
 
-        shader->uniform2fv(LLShaderMgr::DEFERRED_SCREEN_RES, 1, screenRes);
-        shader->uniform1f(LLShaderMgr::BLEND_FACTOR, blend_factor);
+    shader->uniform2fv(LLShaderMgr::DEFERRED_SCREEN_RES, 1, screenRes);
+    shader->uniform1f(LLShaderMgr::BLEND_FACTOR, blend_factor);
 
-        F32      fog_density = pwater->getModifiedWaterFogDensity(underwater);
-
-        if (screentex > -1)
-        {
-            shader->uniform1f(LLShaderMgr::WATER_FOGDENSITY, fog_density);
-            gGL.getTexUnit(screentex)->bind(&gPipeline.mWaterDis);
-        }
+    F32      fog_density = pwater->getModifiedWaterFogDensity(underwater);
 
+    if (screentex > -1)
+	{
+		shader->uniform1f(LLShaderMgr::WATER_FOGDENSITY, fog_density);
+		gGL.getTexUnit(screentex)->bind(&gPipeline.mWaterDis);
+	}
+    
         if (screenDepth > -1)
         {
             gGL.getTexUnit(screenDepth)->bind(&gPipeline.mWaterDis, true);
         }
 
-        if (mShaderLevel == 1)
-        {
-            fog_color.mV[VW] = log(fog_density) / log(2);
-        }
+    if (mShaderLevel == 1)
+    {
+        fog_color.mV[VW] = log(fog_density) / log(2);
+	}
 
         F32 water_height  = environment.getWaterHeight();
         F32 camera_height = LLViewerCamera::getInstance()->getOrigin().mV[2];
@@ -654,45 +654,48 @@ void LLDrawPoolWater::renderWater()
         shader->uniform3fv(LLShaderMgr::WATER_EYEVEC, 1, LLViewerCamera::getInstance()->getOrigin().mV);
 
         shader->uniform4fv(LLShaderMgr::SPECULAR_COLOR, 1, specular.mV);
-        shader->uniform4fv(LLShaderMgr::WATER_FOGCOLOR, 1, fog_color.mV);
+    shader->uniform4fv(LLShaderMgr::WATER_FOGCOLOR, 1, fog_color.mV);
         shader->uniform3fv(LLShaderMgr::WATER_FOGCOLOR_LINEAR, 1, fog_color_linear.mV);
 
-        shader->uniform3fv(LLShaderMgr::WATER_SPECULAR, 1, light_diffuse.mV);
-        shader->uniform1f(LLShaderMgr::WATER_SPECULAR_EXP, light_exp);
+	shader->uniform3fv(LLShaderMgr::WATER_SPECULAR, 1, light_diffuse.mV);
+	shader->uniform1f(LLShaderMgr::WATER_SPECULAR_EXP, light_exp);
 
-        shader->uniform2fv(LLShaderMgr::WATER_WAVE_DIR1, 1, pwater->getWave1Dir().mV);
-        shader->uniform2fv(LLShaderMgr::WATER_WAVE_DIR2, 1, pwater->getWave2Dir().mV);
+    shader->uniform2fv(LLShaderMgr::WATER_WAVE_DIR1, 1, pwater->getWave1Dir().mV);
+    shader->uniform2fv(LLShaderMgr::WATER_WAVE_DIR2, 1, pwater->getWave2Dir().mV);
 
-        shader->uniform3fv(LLShaderMgr::WATER_LIGHT_DIR, 1, light_dir.mV);
+	shader->uniform3fv(LLShaderMgr::WATER_LIGHT_DIR, 1, light_dir.mV);
 
-        shader->uniform3fv(LLShaderMgr::WATER_NORM_SCALE, 1, pwater->getNormalScale().mV);
-        shader->uniform1f(LLShaderMgr::WATER_FRESNEL_SCALE, pwater->getFresnelScale());
-        shader->uniform1f(LLShaderMgr::WATER_FRESNEL_OFFSET, pwater->getFresnelOffset());
-        shader->uniform1f(LLShaderMgr::WATER_BLUR_MULTIPLIER, pwater->getBlurMultiplier());
+	shader->uniform3fv(LLShaderMgr::WATER_NORM_SCALE, 1, pwater->getNormalScale().mV);
+	shader->uniform1f(LLShaderMgr::WATER_FRESNEL_SCALE, pwater->getFresnelScale());
+	shader->uniform1f(LLShaderMgr::WATER_FRESNEL_OFFSET, pwater->getFresnelOffset());
+    shader->uniform1f(LLShaderMgr::WATER_BLUR_MULTIPLIER, pwater->getBlurMultiplier());
 
-        F32 sunAngle    = llmax(0.f, light_dir.mV[1]);
-        F32 scaledAngle = 1.f - sunAngle;
+	F32 sunAngle = llmax(0.f, light_dir.mV[1]);
+	F32 scaledAngle = 1.f - sunAngle;
 
         shader->uniform1i(LLShaderMgr::SUN_UP_FACTOR, sun_up ? 1 : 0);
-        shader->uniform1f(LLShaderMgr::WATER_SUN_ANGLE, sunAngle);
-        shader->uniform1f(LLShaderMgr::WATER_SCALED_ANGLE, scaledAngle);
-        shader->uniform1f(LLShaderMgr::WATER_SUN_ANGLE2, 0.1f + 0.2f * sunAngle);
-        shader->uniform1i(LLShaderMgr::WATER_EDGE_FACTOR, edge ? 1 : 0);
+	shader->uniform1f(LLShaderMgr::WATER_SUN_ANGLE, sunAngle);
+	shader->uniform1f(LLShaderMgr::WATER_SCALED_ANGLE, scaledAngle);
+	shader->uniform1f(LLShaderMgr::WATER_SUN_ANGLE2, 0.1f + 0.2f*sunAngle);
+    shader->uniform1i(LLShaderMgr::WATER_EDGE_FACTOR, edge ? 1 : 0);
 
-        LLVector4 rotated_light_direction = LLEnvironment::instance().getRotatedLightNorm();
-        shader->uniform3fv(LLViewerShaderMgr::LIGHTNORM, 1, rotated_light_direction.mV);
-        shader->uniform3fv(LLShaderMgr::WL_CAMPOSLOCAL, 1, LLViewerCamera::getInstance()->getOrigin().mV);
+    // SL-15861 This was changed from getRotatedLightNorm() as it was causing
+    // lightnorm in shaders\class1\windlight\atmosphericsFuncs.glsl in have inconsistent additive lighting for 180 degrees of the FOV.
+    LLVector4 rotated_light_direction = LLEnvironment::instance().getClampedLightNorm();
+    shader->uniform3fv(LLViewerShaderMgr::LIGHTNORM, 1, rotated_light_direction.mV);
 
-        if (LLViewerCamera::getInstance()->cameraUnderWater())
-        {
-            shader->uniform1f(LLShaderMgr::WATER_REFSCALE, pwater->getScaleBelow());
-        }
-        else
-        {
-            shader->uniform1f(LLShaderMgr::WATER_REFSCALE, pwater->getScaleAbove());
-        }
+    shader->uniform3fv(LLShaderMgr::WL_CAMPOSLOCAL, 1, LLViewerCamera::getInstance()->getOrigin().mV);
 
-        LLGLDisable cullface(GL_CULL_FACE);
+	if (LLViewerCamera::getInstance()->cameraUnderWater())
+	{
+		shader->uniform1f(LLShaderMgr::WATER_REFSCALE, pwater->getScaleBelow());
+	}
+	else
+	{
+		shader->uniform1f(LLShaderMgr::WATER_REFSCALE, pwater->getScaleAbove());
+	}
+
+		LLGLDisable cullface(GL_CULL_FACE);
 
         LLVOWater *water = nullptr;
         for (LLFace *const &face : mDrawFace)
@@ -701,41 +704,41 @@ void LLDrawPoolWater::renderWater()
             water = static_cast<LLVOWater *>(face->getViewerObject());
             if (!water) continue;
 
-            gGL.getTexUnit(diffTex)->bind(face->getTexture());
+			        gGL.getTexUnit(diffTex)->bind(face->getTexture());
 
             if ((bool)edge == (bool) water->getIsEdgePatch())
-            {
-                face->renderIndexed();
+                        {
+                            face->renderIndexed();
 
                 // Note non-void water being drawn, updates required
                 if (!edge)  // SL-16461 remove !LLPipeline::sUseOcclusion check
-                {
-                    sNeedsReflectionUpdate = TRUE;
-                    sNeedsDistortionUpdate = TRUE;
+                    {
+                            sNeedsReflectionUpdate = TRUE;
+                            sNeedsDistortionUpdate = TRUE;
                 }
-            }
+		    }
         }
 
-        shader->disableTexture(LLShaderMgr::ENVIRONMENT_MAP, LLTexUnit::TT_CUBE_MAP);
-        shader->disableTexture(LLShaderMgr::WATER_SCREENTEX);
-        shader->disableTexture(LLShaderMgr::BUMP_MAP);
-        shader->disableTexture(LLShaderMgr::DIFFUSE_MAP);
-        shader->disableTexture(LLShaderMgr::WATER_REFTEX);
-        shader->disableTexture(LLShaderMgr::WATER_SCREENDEPTH);
+	shader->disableTexture(LLShaderMgr::ENVIRONMENT_MAP, LLTexUnit::TT_CUBE_MAP);
+	shader->disableTexture(LLShaderMgr::WATER_SCREENTEX);	
+	shader->disableTexture(LLShaderMgr::BUMP_MAP);
+	shader->disableTexture(LLShaderMgr::DIFFUSE_MAP);
+	shader->disableTexture(LLShaderMgr::WATER_REFTEX);
+	shader->disableTexture(LLShaderMgr::WATER_SCREENDEPTH);
 
         // clean up
         gPipeline.unbindDeferredShader(*shader);
 
         gGL.getTexUnit(bumpTex)->unbind(LLTexUnit::TT_TEXTURE);
         gGL.getTexUnit(bumpTex2)->unbind(LLTexUnit::TT_TEXTURE);
-    }
+        }
 
-    gGL.getTexUnit(0)->activate();
-    gGL.getTexUnit(0)->enable(LLTexUnit::TT_TEXTURE);
-    if (!deferred_render)
-    {
-        gGL.setColorMask(true, false);
-    }
+	gGL.getTexUnit(0)->activate();
+	gGL.getTexUnit(0)->enable(LLTexUnit::TT_TEXTURE);
+	if (!deferred_render)
+	{
+		gGL.setColorMask(true, false);
+	}
 }
 
 LLViewerTexture *LLDrawPoolWater::getDebugTexture()
diff --git a/indra/newview/lldrawpoolwlsky.cpp b/indra/newview/lldrawpoolwlsky.cpp
index 6678e244b9..4bd7536964 100644
--- a/indra/newview/lldrawpoolwlsky.cpp
+++ b/indra/newview/lldrawpoolwlsky.cpp
@@ -266,15 +266,15 @@ void LLDrawPoolWLSky::renderStars(const LLVector3& camPosLocal) const
 	gGL.pushMatrix();
 	gGL.translatef(camPosLocal.mV[0], camPosLocal.mV[1], camPosLocal.mV[2]);
 	gGL.rotatef(gFrameTimeSeconds*0.01f, 0.f, 0.f, 1.f);
-	gCustomAlphaProgram.bind();
-	gCustomAlphaProgram.uniform1f(sCustomAlpha, star_alpha.mV[3]);
+	gStarsProgram.bind();
+	gStarsProgram.uniform1f(sCustomAlpha, star_alpha.mV[3]);
 
 	gSky.mVOWLSkyp->drawStars();
 
     gGL.getTexUnit(0)->unbind(LLTexUnit::TT_TEXTURE);
 	gGL.popMatrix();
-	gCustomAlphaProgram.unbind();
-}
+		gStarsProgram.unbind(); // SL-14113 was gCustomAlphaProgram
+	}
 
 void LLDrawPoolWLSky::renderStarsDeferred(const LLVector3& camPosLocal) const
 {
@@ -319,6 +319,7 @@ void LLDrawPoolWLSky::renderStarsDeferred(const LLVector3& camPosLocal) const
 
 	gGL.pushMatrix();
 	gGL.translatef(camPosLocal.mV[0], camPosLocal.mV[1], camPosLocal.mV[2]);
+	gGL.rotatef(gFrameTimeSeconds*0.01f, 0.f, 0.f, 1.f);
     gDeferredStarProgram.uniform1f(LLShaderMgr::BLEND_FACTOR, blend_factor);
 
     if (LLPipeline::sReflectionRender)
@@ -453,7 +454,8 @@ void LLDrawPoolWLSky::renderHeavenlyBodies()
 {
     if (!gSky.mVOSkyp) return;
 
-	LLGLSPipelineBlendSkyBox gls_skybox(true, false);
+	//LLGLSPipelineBlendSkyBox gls_skybox(true, false);
+    LLGLSPipelineBlendSkyBox gls_skybox(true, true); // SL-14113 we need moon to write to depth to clip stars behind
 
     LLVector3 const & origin = LLViewerCamera::getInstance()->getOrigin();
 	gGL.pushMatrix();
@@ -583,8 +585,8 @@ void LLDrawPoolWLSky::renderDeferred(S32 pass)
     if (gPipeline.canUseWindLightShaders())
     {
         renderSkyHazeDeferred(origin, camHeightLocal);
-        renderStarsDeferred(origin);
         renderHeavenlyBodies();
+        renderStarsDeferred(origin);
         renderSkyCloudsDeferred(origin, camHeightLocal, cloud_shader);
     }
     gGL.setColorMask(true, true);
@@ -602,8 +604,8 @@ void LLDrawPoolWLSky::render(S32 pass)
     LLVector3 const & origin = LLViewerCamera::getInstance()->getOrigin();
     
 	renderSkyHaze(origin, camHeightLocal);    
+    renderHeavenlyBodies();
     renderStars(origin);
-    renderHeavenlyBodies();	
 	renderSkyClouds(origin, camHeightLocal, cloud_shader);
 
 	gGL.getTexUnit(0)->unbind(LLTexUnit::TT_TEXTURE);
diff --git a/indra/newview/llviewershadermgr.cpp b/indra/newview/llviewershadermgr.cpp
index 9e2d28f29e..ff9f767940 100644
--- a/indra/newview/llviewershadermgr.cpp
+++ b/indra/newview/llviewershadermgr.cpp
@@ -74,7 +74,7 @@ LLVector4			gShinyOrigin;
 LLGLSLShader	gOcclusionProgram;
 LLGLSLShader    gSkinnedOcclusionProgram;
 LLGLSLShader	gOcclusionCubeProgram;
-LLGLSLShader	gCustomAlphaProgram;
+LLGLSLShader	gCustomAlphaProgram; // SL-14113 This used to be used for the stars with Atmospheric Shaders: OFF
 LLGLSLShader	gGlowCombineProgram;
 LLGLSLShader	gSplatTextureRectProgram;
 LLGLSLShader	gReflectionMipProgram;
@@ -143,6 +143,8 @@ LLGLSLShader		gObjectAlphaMaskNoColorProgram;
 LLGLSLShader		gObjectAlphaMaskNoColorWaterProgram;
 
 //environment shaders
+LLGLSLShader		gMoonProgram;
+LLGLSLShader		gStarsProgram;
 LLGLSLShader		gTerrainProgram;
 LLGLSLShader		gTerrainWaterProgram;
 LLGLSLShader		gWaterProgram;
@@ -753,6 +755,9 @@ void LLViewerShaderMgr::unloadShaders()
 	gWaterProgram.unload();
     gWaterEdgeProgram.unload();
 	gUnderWaterProgram.unload();
+
+	gMoonProgram.unload();
+	gStarsProgram.unload();
 	gTerrainProgram.unload();
 	gTerrainWaterProgram.unload();
 	gGlowProgram.unload();
@@ -986,6 +991,34 @@ BOOL LLViewerShaderMgr::loadShadersEnvironment()
 		llassert(success);
 	}
 
+	if (success)
+	{
+		gStarsProgram.mName = "Environment Stars Shader";
+		gStarsProgram.mShaderFiles.clear();
+		gStarsProgram.mShaderFiles.push_back(make_pair("environment/starsV.glsl", GL_VERTEX_SHADER_ARB));
+		gStarsProgram.mShaderFiles.push_back(make_pair("environment/starsF.glsl", GL_FRAGMENT_SHADER_ARB));
+		gStarsProgram.mShaderLevel = mShaderLevel[SHADER_ENVIRONMENT];
+        gStarsProgram.addConstant( LLGLSLShader::SHADER_CONST_STAR_DEPTH ); // SL-14113
+		success = gStarsProgram.createShader(NULL, NULL);
+		llassert(success);
+	}
+
+	if (success)
+	{
+		gMoonProgram.mName = "Environment Moon Shader";
+		gMoonProgram.mShaderFiles.clear();
+		gMoonProgram.mShaderFiles.push_back(make_pair("environment/moonV.glsl", GL_VERTEX_SHADER_ARB));
+		gMoonProgram.mShaderFiles.push_back(make_pair("environment/moonF.glsl", GL_FRAGMENT_SHADER_ARB));
+		gMoonProgram.mShaderLevel = mShaderLevel[SHADER_ENVIRONMENT];
+        gMoonProgram.addConstant( LLGLSLShader::SHADER_CONST_CLOUD_MOON_DEPTH ); // SL-14113
+		success = gMoonProgram.createShader(NULL, NULL);
+		if (success)
+		{
+			gMoonProgram.bind();
+			gMoonProgram.uniform1i(sTex0, 0);
+		}
+	}
+
 	if (!success)
 	{
 		mShaderLevel[SHADER_ENVIRONMENT] = 0;
@@ -2801,6 +2834,7 @@ BOOL LLViewerShaderMgr::loadShadersDeferred()
 		gDeferredWLCloudProgram.mShaderFiles.push_back(make_pair("deferred/cloudsF.glsl", GL_FRAGMENT_SHADER));
 		gDeferredWLCloudProgram.mShaderLevel = mShaderLevel[SHADER_DEFERRED];
 		gDeferredWLCloudProgram.mShaderGroup = LLGLSLShader::SG_SKY;
+        gDeferredWLCloudProgram.addConstant( LLGLSLShader::SHADER_CONST_CLOUD_MOON_DEPTH ); // SL-14113
 		success = gDeferredWLCloudProgram.createShader(NULL, NULL);
 		llassert(success);
 	}
@@ -2840,6 +2874,7 @@ BOOL LLViewerShaderMgr::loadShadersDeferred()
         gDeferredWLMoonProgram.mShaderFiles.push_back(make_pair("deferred/moonF.glsl", GL_FRAGMENT_SHADER));
         gDeferredWLMoonProgram.mShaderLevel = mShaderLevel[SHADER_DEFERRED];
         gDeferredWLMoonProgram.mShaderGroup = LLGLSLShader::SG_SKY;
+        gDeferredWLMoonProgram.addConstant( LLGLSLShader::SHADER_CONST_CLOUD_MOON_DEPTH ); // SL-14113
  	 	success = gDeferredWLMoonProgram.createShader(NULL, NULL);
         llassert(success);
  	}
@@ -2852,6 +2887,7 @@ BOOL LLViewerShaderMgr::loadShadersDeferred()
 		gDeferredStarProgram.mShaderFiles.push_back(make_pair("deferred/starsF.glsl", GL_FRAGMENT_SHADER));
 		gDeferredStarProgram.mShaderLevel = mShaderLevel[SHADER_DEFERRED];
 		gDeferredStarProgram.mShaderGroup = LLGLSLShader::SG_SKY;
+        gDeferredStarProgram.addConstant( LLGLSLShader::SHADER_CONST_STAR_DEPTH ); // SL-14113
 		success = gDeferredStarProgram.createShader(NULL, NULL);
         llassert(success);
 	}
@@ -3901,6 +3937,7 @@ BOOL LLViewerShaderMgr::loadShadersWindLight()
         gWLCloudProgram.mShaderFiles.push_back(make_pair("windlight/cloudsF.glsl", GL_FRAGMENT_SHADER));
         gWLCloudProgram.mShaderLevel = mShaderLevel[SHADER_WINDLIGHT];
         gWLCloudProgram.mShaderGroup = LLGLSLShader::SG_SKY;
+        gWLCloudProgram.addConstant( LLGLSLShader::SHADER_CONST_CLOUD_MOON_DEPTH ); // SL-14113
         success = gWLCloudProgram.createShader(NULL, NULL);
     }
 
@@ -3937,6 +3974,7 @@ BOOL LLViewerShaderMgr::loadShadersWindLight()
         gWLMoonProgram.mShaderFiles.push_back(make_pair("windlight/moonF.glsl", GL_FRAGMENT_SHADER));
         gWLMoonProgram.mShaderLevel = mShaderLevel[SHADER_WINDLIGHT];
         gWLMoonProgram.mShaderGroup = LLGLSLShader::SG_SKY;
+        gWLMoonProgram.addConstant( LLGLSLShader::SHADER_CONST_CLOUD_MOON_DEPTH ); // SL-14113
         success = gWLMoonProgram.createShader(NULL, NULL);
     }
 #endif
diff --git a/indra/newview/llviewershadermgr.h b/indra/newview/llviewershadermgr.h
index 4ed6b02728..e32051f830 100644
--- a/indra/newview/llviewershadermgr.h
+++ b/indra/newview/llviewershadermgr.h
@@ -211,6 +211,8 @@ extern LLGLSLShader			gObjectShinyProgram;
 extern LLGLSLShader			gObjectShinyWaterProgram;
 
 //environment shaders
+extern LLGLSLShader			gMoonProgram;
+extern LLGLSLShader			gStarsProgram;
 extern LLGLSLShader			gTerrainProgram;
 extern LLGLSLShader			gTerrainWaterProgram;
 extern LLGLSLShader			gWaterProgram;
diff --git a/indra/newview/llviewerstats.cpp b/indra/newview/llviewerstats.cpp
index 32fb7c13a9..ee39b7d02f 100644
--- a/indra/newview/llviewerstats.cpp
+++ b/indra/newview/llviewerstats.cpp
@@ -65,6 +65,53 @@
 #include "llinventorymodel.h"
 #include "lluiusage.h"
 
+// "Minimal Vulkan" to get max API Version
+
+// Calls
+    #if defined(_WIN32)
+        #define VKAPI_ATTR
+        #define VKAPI_CALL __stdcall
+        #define VKAPI_PTR  VKAPI_CALL
+    #else
+        #define VKAPI_ATTR
+        #define VKAPI_CALL
+        #define VKAPI_PTR
+    #endif // _WIN32
+
+// Macros
+    // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+    // |31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|15|14|13|12|11|10| 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
+    // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+    // <variant> <-------major-------><-----------minor-----------> <--------------patch-------------->
+    //      0x7          0x7F                     0x3FF                           0xFFF
+    #define VK_API_VERSION_MAJOR(  version) (((uint32_t)(version) >> 22) & 0x07FU)  //  7 bits
+    #define VK_API_VERSION_MINOR(  version) (((uint32_t)(version) >> 12) & 0x3FFU)  // 10 bits
+    #define VK_API_VERSION_PATCH(  version) (((uint32_t)(version)      ) & 0xFFFU)  // 12 bits
+    #define VK_API_VERSION_VARIANT(version) (((uint32_t)(version) >> 29) & 0x007U)  //  3 bits
+
+    // NOTE: variant is first parameter!  This is to match vulkan/vulkan_core.h
+    #define VK_MAKE_API_VERSION(variant, major, minor, patch) (0\
+        | (((uint32_t)(major   & 0x07FU)) << 22) \
+        | (((uint32_t)(minor   & 0x3FFU)) << 12) \
+        | (((uint32_t)(patch   & 0xFFFU))      ) \
+        | (((uint32_t)(variant & 0x007U)) << 29) )
+
+    #define VK_DEFINE_HANDLE(object) typedef struct object##_T* object;
+
+// Types
+    VK_DEFINE_HANDLE(VkInstance);
+
+    typedef enum VkResult
+    {
+        VK_SUCCESS = 0,
+        VK_RESULT_MAX_ENUM = 0x7FFFFFFF
+    } VkResult;
+
+// Prototypes
+    typedef void               (VKAPI_PTR *PFN_vkVoidFunction            )(void);
+    typedef PFN_vkVoidFunction (VKAPI_PTR *PFN_vkGetInstanceProcAddr     )(VkInstance instance, const char* pName);
+    typedef VkResult           (VKAPI_PTR *PFN_vkEnumerateInstanceVersion)(uint32_t* pApiVersion);
+
 namespace LLStatViewer
 {
 
@@ -592,19 +639,76 @@ void send_viewer_stats(bool include_preferences)
     // detailed information on versions and extensions can come later.
     static bool vulkan_oneshot = false;
     static bool vulkan_detected = false;
+    static std::string vulkan_max_api_version( "0.0" ); // Unknown/None
 
     if (!vulkan_oneshot)
     {
-        HMODULE vulkan_loader = LoadLibraryExA("vulkan-1.dll", NULL, LOAD_LIBRARY_AS_DATAFILE);
+        // The 32-bit and 64-bit versions normally exist in:
+        //     C:\Windows\System32
+        //     C:\Windows\SysWOW64
+        HMODULE vulkan_loader = LoadLibraryA("vulkan-1.dll");
         if (NULL != vulkan_loader)
         {
             vulkan_detected = true;
+            vulkan_max_api_version = "1.0"; // We have at least 1.0.  See the note about vkEnumerateInstanceVersion() below.
+
+            // We use Run-Time Dynamic Linking (via GetProcAddress()) instead of Load-Time Dynamic Linking (via directly calling vkGetInstanceProcAddr()).
+            // This allows us to:
+            //   a) not need the header: #include <vulkan/vulkan.h>
+            //      (and not need to set the corresponding "Additional Include Directories" as long as we provide the equivalent Vulkan types/prototypes/etc.)
+            //   b) not need to link to: vulkan-1.lib
+            //      (and not need to set the corresponding "Additional Library Directories")
+            // The former will allow Second Life to start and run even if the vulkan.dll is missing.
+            // The latter will require us to:
+            //   a) link with vulkan-1.lib
+            //   b) cause a System Error at startup if the .dll is not found:
+            //      "The code execution cannot proceed because vulkan-1.dll was not found."
+            //
+            // See:
+            //   https://docs.microsoft.com/en-us/windows/win32/dlls/using-run-time-dynamic-linking
+            //   https://docs.microsoft.com/en-us/windows/win32/dlls/run-time-dynamic-linking
+
+            // NOTE: Technically we can use GetProcAddress() as a replacement for vkGetInstanceProcAddr()
+            //       but the canonical recommendation (mandate?) is to use vkGetInstanceProcAddr().
+            PFN_vkGetInstanceProcAddr pGetInstanceProcAddr = (PFN_vkGetInstanceProcAddr) GetProcAddress(vulkan_loader, "vkGetInstanceProcAddr");
+            if(pGetInstanceProcAddr)
+            {
+                // Check for vkEnumerateInstanceVersion.  If it exists then we have at least 1.1 and can query the max API version.
+                // NOTE: Each VkPhysicalDevice that supports Vulkan has its own VkPhysicalDeviceProperties.apiVersion which is separate from the max API version!
+                // See: https://www.lunarg.com/wp-content/uploads/2019/02/Vulkan-1.1-Compatibility-Statement_01_19.pdf
+                PFN_vkEnumerateInstanceVersion pEnumerateInstanceVersion = (PFN_vkEnumerateInstanceVersion) pGetInstanceProcAddr(NULL, "vkEnumerateInstanceVersion");
+                if(pEnumerateInstanceVersion)
+                {
+                    uint32_t version = VK_MAKE_API_VERSION(0,1,1,0);   // e.g. 4202631 = 1.2.135.0
+                    VkResult status  = pEnumerateInstanceVersion( &version );
+                    if (status != VK_SUCCESS)
+                    {
+                        LL_INFOS("Vulkan") << "Failed to get Vulkan version.  Assuming 1.0" << LL_ENDL;
+                    }
+                    else
+                    {
+                        // https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/vkspec.html#extendingvulkan-coreversions-versionnumbers
+                        int major   = VK_API_VERSION_MAJOR  ( version );
+                        int minor   = VK_API_VERSION_MINOR  ( version );
+                        int patch   = VK_API_VERSION_PATCH  ( version );
+                        int variant = VK_API_VERSION_VARIANT( version );
+
+                        vulkan_max_api_version = llformat( "%d.%d.%d.%d", major, minor, patch, variant );
+                        LL_INFOS("Vulkan") << "Vulkan API version: " << vulkan_max_api_version << ", Raw version: " << version << LL_ENDL;
+                    }
+                }
+            }
+            else
+            {
+                LL_WARNS("Vulkan") << "FAILED to get Vulkan vkGetInstanceProcAddr()!" << LL_ENDL;
+            }
             FreeLibrary(vulkan_loader);
         }
         vulkan_oneshot = true;
     }
 
     misc["string_1"] = vulkan_detected ? llformat("Vulkan driver is detected") : llformat("No Vulkan driver detected");
+    misc["VulkanMaxApiVersion"] = vulkan_max_api_version;
 
 #else
     misc["string_1"] = llformat("Unused");