From d23969b8d35d65e62ed32a2df78f819bbec1fe0d Mon Sep 17 00:00:00 2001
From: Ylva Selling <ylva.selling@gmail.com>
Date: Tue, 21 Jun 2022 10:47:44 -0400
Subject: [PATCH] Add gamma correction to screen space renderable (SSR) shader,
 property for SSR and default value gamma = 2.2 for sky browser display copies

---
 .../rendering/screenspacerenderable.h         |  3 ++-
 modules/base/shaders/screenspace_fs.glsl      |  2 ++
 modules/skybrowser/skybrowsermodule_lua.inl   |  1 +
 src/rendering/screenspacerenderable.cpp       | 19 ++++++++++++++++---
 4 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/include/openspace/rendering/screenspacerenderable.h b/include/openspace/rendering/screenspacerenderable.h
index 9c153d3576..ff964ec4f3 100644
--- a/include/openspace/rendering/screenspacerenderable.h
+++ b/include/openspace/rendering/screenspacerenderable.h
@@ -130,6 +130,7 @@ protected:
     properties::Vec3Property _localRotation;
 
     properties::FloatProperty _scale;
+    properties::FloatProperty _gamma;
     properties::Vec3Property _multiplyColor;
     properties::Vec4Property _backgroundColor;
     properties::FloatProperty _opacity;
@@ -137,7 +138,7 @@ protected:
     properties::TriggerProperty _delete;
 
     glm::ivec2 _objectSize = glm::ivec2(0);
-    UniformCache(color, opacity, mvp, texture, backgroundColor) _uniformCache;
+    UniformCache(color, opacity, mvp, texture, backgroundColor, gamma) _uniformCache;
     std::unique_ptr<ghoul::opengl::ProgramObject> _shader;
 };
 
diff --git a/modules/base/shaders/screenspace_fs.glsl b/modules/base/shaders/screenspace_fs.glsl
index b112559485..2c4063f8c8 100644
--- a/modules/base/shaders/screenspace_fs.glsl
+++ b/modules/base/shaders/screenspace_fs.glsl
@@ -32,6 +32,7 @@ uniform sampler2D tex;
 uniform vec3 color = vec3(1.0);
 uniform float opacity = 1.0;
 uniform vec4 backgroundColor = vec4(0.0);
+uniform float gamma = 1.0;
 
 Fragment getFragment() {
   Fragment frag;
@@ -44,5 +45,6 @@ Fragment getFragment() {
   }
 
   frag.depth = vs_depth;
+  frag.color.rgb = pow(frag.color.rgb, vec3(1.0/(gamma + 0.000001)));
   return frag;
 }
diff --git a/modules/skybrowser/skybrowsermodule_lua.inl b/modules/skybrowser/skybrowsermodule_lua.inl
index 811bc881a8..706bf4dc32 100644
--- a/modules/skybrowser/skybrowsermodule_lua.inl
+++ b/modules/skybrowser/skybrowsermodule_lua.inl
@@ -435,6 +435,7 @@ namespace {
         "Name = '" + nameBrowser + "',"
         "Url = '" + url + "',"
         "FaceCamera = false,"
+        "Gamma = 2.2,"
         "CartesianPosition = " + ghoul::to_string(positionBrowser) +
      "}";
 
diff --git a/src/rendering/screenspacerenderable.cpp b/src/rendering/screenspacerenderable.cpp
index 8fd9c41723..df00e38361 100644
--- a/src/rendering/screenspacerenderable.cpp
+++ b/src/rendering/screenspacerenderable.cpp
@@ -42,8 +42,8 @@
 #include <variant>
 
 namespace {
-    constexpr const std::array<const char*, 5> UniformNames = {
-        "color", "opacity", "mvpMatrix", "tex", "backgroundColor"
+    constexpr const std::array<const char*, 6> UniformNames = {
+        "color", "opacity", "mvpMatrix", "tex", "backgroundColor", "gamma"
     };
 
     constexpr openspace::properties::Property::PropertyInfo EnabledInfo = {
@@ -150,6 +150,12 @@ namespace {
         "the camera."
     };
 
+    constexpr openspace::properties::Property::PropertyInfo GammaInfo = {
+        "Gamma",
+        "Gamma Correction",
+        "Sets the gamma correction of the texture."
+    };
+
     float wrap(float value, float min, float max) {
         return glm::mod(value - min, max - min) + min;
     }
@@ -190,6 +196,9 @@ namespace {
         // [[codegen::verbatim(ScaleInfo.description)]]
         std::optional<float> scale;
 
+        // [[codegen::verbatim(UseRadiusAzimuthElevationInfo.description)]]
+        std::optional<float> gamma;
+
         // [[codegen::verbatim(UsePerspectiveProjectionInfo.description)]]
         std::optional<bool> usePerspectiveProjection;
 
@@ -286,6 +295,7 @@ ScreenSpaceRenderable::ScreenSpaceRenderable(const ghoul::Dictionary& dictionary
     , _opacity(OpacityInfo, 1.f, 0.f, 1.f)
     , _fade(FadeInfo, 1.f, 0.f, 1.f)
     , _delete(DeleteInfo)
+    , _gamma(GammaInfo, 1.f, 0.f, 10.f)
 {
     const Parameters p = codegen::bake<Parameters>(dictionary);
 
@@ -303,6 +313,7 @@ ScreenSpaceRenderable::ScreenSpaceRenderable(const ghoul::Dictionary& dictionary
     addProperty(_faceCamera);
     addProperty(_cartesianPosition);
     addProperty(_raePosition);
+    addProperty(_gamma);
 
     // Setting spherical/euclidean onchange handler
     _useRadiusAzimuthElevation.onChange([this]() {
@@ -329,6 +340,8 @@ ScreenSpaceRenderable::ScreenSpaceRenderable(const ghoul::Dictionary& dictionary
     _backgroundColor.setViewOption(properties::Property::ViewOptions::Color);
 
     _enabled = p.enabled.value_or(_enabled);
+    _gamma = p.gamma.value_or(_gamma);
+
     _useRadiusAzimuthElevation =
         p.useRadiusAzimuthElevation.value_or(_useRadiusAzimuthElevation);
 
@@ -591,7 +604,7 @@ void ScreenSpaceRenderable::draw(glm::mat4 modelTransform) {
     _shader->setUniform(_uniformCache.color, _multiplyColor);
     _shader->setUniform(_uniformCache.opacity, opacity());
     _shader->setUniform(_uniformCache.backgroundColor, _backgroundColor);
-
+    _shader->setUniform(_uniformCache.gamma, _gamma);
     _shader->setUniform(
         _uniformCache.mvp,
         global::renderEngine->scene()->camera()->viewProjectionMatrix() * modelTransform