From 38690397c28004f83c4a5acdaf8d3cd53f600daa Mon Sep 17 00:00:00 2001
From: JetSetIlly <stephen.t.illingworth@gmail.com>
Date: Sat, 27 Apr 2024 06:50:31 +0100
Subject: [PATCH] added TV saturation control

---
 gui/fonts/fonts.go                 |  1 +
 gui/sdlimgui/gl32_shaders.go       |  3 +++
 gui/sdlimgui/shaders/tv_color.frag |  7 +++++++
 gui/sdlimgui/win_prefs_tv.go       | 16 ++++++++++++++++
 4 files changed, 27 insertions(+)

diff --git a/gui/fonts/fonts.go b/gui/fonts/fonts.go
index 2b7f956c..586b90be 100644
--- a/gui/fonts/fonts.go
+++ b/gui/fonts/fonts.go
@@ -95,6 +95,7 @@ const (
 	Directory              = '\uf07c'
 	TVBrightness           = '\uf185'
 	TVContrast             = '\uf042'
+	TVSaturation           = '\uf0e9'
 	TVHue                  = '\uf043'
 )
 
diff --git a/gui/sdlimgui/gl32_shaders.go b/gui/sdlimgui/gl32_shaders.go
index 60740fae..c0e7ff93 100644
--- a/gui/sdlimgui/gl32_shaders.go
+++ b/gui/sdlimgui/gl32_shaders.go
@@ -196,6 +196,7 @@ type tvColorShader struct {
 	shader
 	brightness int32
 	contrast   int32
+	saturation int32
 	hue        int32
 }
 
@@ -204,6 +205,7 @@ func newTVColorShader() shaderProgram {
 	sh.createProgram(string(shaders.YFlipVertexShader), string(shaders.TVColorShader))
 	sh.brightness = gl.GetUniformLocation(sh.handle, gl.Str("Brightness"+"\x00"))
 	sh.contrast = gl.GetUniformLocation(sh.handle, gl.Str("Contrast"+"\x00"))
+	sh.saturation = gl.GetUniformLocation(sh.handle, gl.Str("Saturation"+"\x00"))
 	sh.hue = gl.GetUniformLocation(sh.handle, gl.Str("Hue"+"\x00"))
 	return sh
 }
@@ -212,6 +214,7 @@ func (sh *tvColorShader) setAttributesArgs(env shaderEnvironment, prefs crtSeqPr
 	sh.shader.setAttributes(env)
 	gl.Uniform1f(sh.contrast, float32(prefs.Contrast))
 	gl.Uniform1f(sh.brightness, float32(prefs.Brightness))
+	gl.Uniform1f(sh.saturation, float32(prefs.Saturation))
 	gl.Uniform1f(sh.hue, float32(prefs.Hue))
 }
 
diff --git a/gui/sdlimgui/shaders/tv_color.frag b/gui/sdlimgui/shaders/tv_color.frag
index d03b30bd..ffdb4391 100644
--- a/gui/sdlimgui/shaders/tv_color.frag
+++ b/gui/sdlimgui/shaders/tv_color.frag
@@ -39,6 +39,13 @@ void main()
 	}
 	adjust *= contrast;
 
+	// saturation
+	adjust *= mat3(
+		vec3(1, 0, 0),
+		vec3(0, Saturation, 0),
+		vec3(0, 0, Saturation)
+	);
+
 	// hue
 	float hue = 2 * PI * Hue;
 	adjust *= mat3(
diff --git a/gui/sdlimgui/win_prefs_tv.go b/gui/sdlimgui/win_prefs_tv.go
index 1fc3d65e..cae1b568 100644
--- a/gui/sdlimgui/win_prefs_tv.go
+++ b/gui/sdlimgui/win_prefs_tv.go
@@ -29,6 +29,8 @@ func (win *winPrefs) drawTV() {
 	imgui.Spacing()
 	win.drawContrast()
 	imgui.Spacing()
+	win.drawSaturation()
+	imgui.Spacing()
 	win.drawHue()
 }
 
@@ -60,6 +62,20 @@ func (win *winPrefs) drawContrast() {
 	}
 }
 
+func (win *winPrefs) drawSaturation() {
+	imgui.Text(fmt.Sprintf("%c Saturation", fonts.TVSaturation))
+
+	f := float32(win.img.crtPrefs.Saturation.Get().(float64))
+
+	minv := float32(0.1)
+	maxv := float32(1.90)
+	label := fmt.Sprintf("%.0f", 100*(f-minv)/(maxv-minv))
+
+	if imgui.SliderFloatV("##saturation", &f, minv, maxv, label, imgui.SliderFlagsNone) {
+		win.img.crtPrefs.Saturation.Set(f)
+	}
+}
+
 func (win *winPrefs) drawHue() {
 	imgui.Text(fmt.Sprintf("%c Hue", fonts.TVHue))