From c21752f93be28acdfc601ea3b3e9db3cebd18f75 Mon Sep 17 00:00:00 2001
From: Jonathas Costa <jon.costa@gmail.com>
Date: Wed, 17 Feb 2021 21:31:42 -0500
Subject: [PATCH] Fixed the forward/backward scattering effects.

---
 .../shaders/advanced_rings_fs.glsl            |  5 +++--
 modules/globebrowsing/src/ringscomponent.cpp  | 19 +++++++++++++++----
 modules/globebrowsing/src/ringscomponent.h    |  2 +-
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/modules/globebrowsing/shaders/advanced_rings_fs.glsl b/modules/globebrowsing/shaders/advanced_rings_fs.glsl
index 9219fa66b1..d3b7f96fe3 100644
--- a/modules/globebrowsing/shaders/advanced_rings_fs.glsl
+++ b/modules/globebrowsing/shaders/advanced_rings_fs.glsl
@@ -43,6 +43,7 @@ uniform vec2 textureOffset;
 uniform float colorFilterValue;
 
 uniform vec3 sunPosition;
+uniform vec3 sunPositionObj;
 uniform vec3 camPositionObj;
 uniform float _nightFactor;
 uniform float zFightingPercentage;
@@ -73,11 +74,11 @@ Fragment getFragment() {
     }
 
     vec4 colorBckwrd  = texture(ringTextureBckwrd, texCoord);
-    vec4 colorFwrd    = texture(ringTextureFwrd, texCoord);
+    vec4 colorFwrd    = vec4(0.8, 0.8, 0.8, 1.0) * texture(ringTextureFwrd, texCoord);
     vec4 colorMult    = texture(ringTextureColor, texCoord);
     vec4 transparency = texture(ringTextureTransparency, texCoord);
 
-    float lerpFactor = (1.f + dot(camPositionObj.xyz, sunPosition.xyz)) * 0.5f;
+    float lerpFactor =  dot(camPositionObj, sunPositionObj);
 
     // Jon Colors:
     //vec4 diffuse = mix(colorFwrd * vec4(1, 0.88, 0.82, 1.0), colorBckwrd * vec4(1, 0.88, 0.82, 1.0), lerpFactor);
diff --git a/modules/globebrowsing/src/ringscomponent.cpp b/modules/globebrowsing/src/ringscomponent.cpp
index 9a047868fe..c9d11c4483 100644
--- a/modules/globebrowsing/src/ringscomponent.cpp
+++ b/modules/globebrowsing/src/ringscomponent.cpp
@@ -59,11 +59,11 @@ namespace {
         "zFightingPercentage"
     };
 
-    constexpr const std::array<const char*, 14> UniformNamesAdvancedRings = {
+    constexpr const std::array<const char*, 15> UniformNamesAdvancedRings = {
         "modelViewProjectionMatrix", "textureOffset", "colorFilterValue", "_nightFactor",
-        "sunPosition", "camPositionObj", "ringTextureFwrd", "ringTextureBckwrd", 
-        "ringTextureUnlit", "ringTextureColor", "ringTextureTransparency", "shadowMatrix", 
-        "shadowMapTexture", "zFightingPercentage"
+        "sunPosition", "sunPositionObj", "camPositionObj", "ringTextureFwrd", 
+        "ringTextureBckwrd", "ringTextureUnlit", "ringTextureColor", 
+        "ringTextureTransparency", "shadowMatrix", "shadowMapTexture", "zFightingPercentage"
     };
 
     constexpr const std::array<const char*, 3> GeomUniformNames = {
@@ -476,6 +476,17 @@ void RingsComponent::draw(const RenderData& data,
             _shader->setUniform(_uniformCacheAdvancedRings.colorFilterValue, _colorFilter);
             _shader->setUniform(_uniformCacheAdvancedRings.nightFactor, _nightFactor);
             _shader->setUniform(_uniformCacheAdvancedRings.sunPosition, _sunPosition);
+            
+            const glm::dmat4 inverseModelTransform = glm::inverse(modelTransform);
+
+            glm::vec3 sunPositionObjectSpace = glm::normalize(
+                glm::vec3(inverseModelTransform * glm::vec4(_sunPosition, 0.0))
+            );
+
+            _shader->setUniform(
+                _uniformCacheAdvancedRings.sunPositionObj, 
+                sunPositionObjectSpace
+            );
             _shader->setUniform(
                 _uniformCacheAdvancedRings.zFightingPercentage, 
                 _zFightingPercentage
diff --git a/modules/globebrowsing/src/ringscomponent.h b/modules/globebrowsing/src/ringscomponent.h
index b4e3a9cda3..661096d3b7 100644
--- a/modules/globebrowsing/src/ringscomponent.h
+++ b/modules/globebrowsing/src/ringscomponent.h
@@ -97,7 +97,7 @@ private:
         sunPosition, ringTexture, shadowMatrix, shadowMapTexture, zFightingPercentage
     ) _uniformCache;
     UniformCache(modelViewProjectionMatrix, textureOffset, colorFilterValue, nightFactor,
-        sunPosition, camPositionObj, ringTextureFwrd, ringTextureBckwrd,
+        sunPosition, sunPositionObj, camPositionObj, ringTextureFwrd, ringTextureBckwrd,
         ringTextureUnlit, ringTextureColor, ringTextureTransparency, shadowMatrix, 
         shadowMapTexture, zFightingPercentage
     ) _uniformCacheAdvancedRings;