From d9f38dab3e4d617872724d1b43552ec1f1103f61 Mon Sep 17 00:00:00 2001
From: Leon Styhre <leon@leonstyhre.com>
Date: Fri, 3 Mar 2023 22:37:39 +0100
Subject: [PATCH] Added support for changing the saturation for font textures.

---
 es-core/src/components/TextComponent.cpp |  7 +++++++
 es-core/src/components/TextComponent.h   |  1 +
 es-core/src/resources/Font.cpp           |  8 ++++++++
 es-core/src/resources/Font.h             |  1 +
 resources/shaders/glsl/core.glsl         | 11 +++++++++--
 5 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/es-core/src/components/TextComponent.cpp b/es-core/src/components/TextComponent.cpp
index affcd4840..92e6f86d9 100644
--- a/es-core/src/components/TextComponent.cpp
+++ b/es-core/src/components/TextComponent.cpp
@@ -115,6 +115,13 @@ void TextComponent::setOpacity(float opacity)
         mTextCache->setOpacity(mThemeOpacity);
 }
 
+void TextComponent::setSaturation(float saturation)
+{
+    mSaturation = saturation;
+    if (mTextCache)
+        mTextCache->setSaturation(saturation);
+}
+
 void TextComponent::setDimming(float dimming)
 {
     mDimming = dimming;
diff --git a/es-core/src/components/TextComponent.h b/es-core/src/components/TextComponent.h
index 17e5118fa..96d8834c8 100644
--- a/es-core/src/components/TextComponent.h
+++ b/es-core/src/components/TextComponent.h
@@ -62,6 +62,7 @@ public:
     float const getColorOpacity() const override { return mColorOpacity; }
 
     void setOpacity(float opacity) override;
+    void setSaturation(float saturation) override;
     void setDimming(float dimming) override;
 
     void setSelectable(bool status) { mSelectable = status; }
diff --git a/es-core/src/resources/Font.cpp b/es-core/src/resources/Font.cpp
index cf23b0c6e..f1ecf5652 100644
--- a/es-core/src/resources/Font.cpp
+++ b/es-core/src/resources/Font.cpp
@@ -826,6 +826,14 @@ void TextCache::setOpacity(float opacity)
     }
 }
 
+void TextCache::setSaturation(float saturation)
+{
+    for (auto it = vertexLists.begin(); it != vertexLists.end(); ++it) {
+        for (auto it2 = it->verts.begin(); it2 != it->verts.end(); ++it2)
+            it2->saturation = saturation;
+    }
+}
+
 void TextCache::setDimming(float dimming)
 {
     for (auto it = vertexLists.begin(); it != vertexLists.end(); ++it) {
diff --git a/es-core/src/resources/Font.h b/es-core/src/resources/Font.h
index ece1cd7c9..86990aa53 100644
--- a/es-core/src/resources/Font.h
+++ b/es-core/src/resources/Font.h
@@ -238,6 +238,7 @@ public:
 
     void setColor(unsigned int color);
     void setOpacity(float opacity);
+    void setSaturation(float saturation);
     void setDimming(float dimming);
 
     friend Font;
diff --git a/resources/shaders/glsl/core.glsl b/resources/shaders/glsl/core.glsl
index cc1f04dcd..da5609e47 100644
--- a/resources/shaders/glsl/core.glsl
+++ b/resources/shaders/glsl/core.glsl
@@ -79,8 +79,8 @@ void main()
         sampledColor.rgb *= sampledColor.a;
     }
 
-    // Saturation.
-    if (saturation != 1.0) {
+    // Saturation, except for font textures.
+    if (saturation != 1.0 && 0x0u == (shaderFlags & 0x2u)) {
         vec3 grayscale;
         // Premultiplied textures are all in BGRA format.
         if (0x0u != (shaderFlags & 0x01u))
@@ -105,6 +105,13 @@ void main()
         sampledColor *= color;
     }
 
+    // Saturation for font textures.
+    if (saturation != 1.0 && 0x0u != (shaderFlags & 0x2u)) {
+        vec3 grayscale = vec3(dot(sampledColor.rgb, vec3(0.299, 0.587, 0.114)));
+        vec3 blendedColor = mix(grayscale, sampledColor.rgb, saturation);
+        sampledColor = vec4(blendedColor, sampledColor.a);
+    }
+
     // When post-processing we drop the alpha channel to avoid strange issues with some
     // graphics drivers.
     if (0x0u != (shaderFlags & 0x4u))