From d73d3b448094688bcc8cd543d5cfdbf282b43d2d Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 9 Sep 2018 21:52:48 -0400
Subject: [PATCH] Adds a left border to complement the right.

---
 Outputs/CRT/Internals/CRTOpenGL.cpp            | 4 +++-
 Outputs/CRT/Internals/CRTOpenGL.hpp            | 1 +
 Outputs/CRT/Internals/Shaders/OutputShader.cpp | 5 +++++
 Outputs/CRT/Internals/Shaders/OutputShader.hpp | 6 ++++++
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/Outputs/CRT/Internals/CRTOpenGL.cpp b/Outputs/CRT/Internals/CRTOpenGL.cpp
index 6510dc471..2342ccb99 100644
--- a/Outputs/CRT/Internals/CRTOpenGL.cpp
+++ b/Outputs/CRT/Internals/CRTOpenGL.cpp
@@ -228,7 +228,8 @@ void OpenGLOutputBuilder::draw_frame(unsigned int output_width, unsigned int out
 			last_output_width_ = output_width;
 			last_output_height_ = output_height;
 
-			// Configure a right gutter to crop the right-hand 2% of the display.
+			// Configure right and left gutters to crop the left- and right-hand 1% of the display.
+			left_overlay_.reset(new OpenGL::Rectangle(output_shader_program_->get_left_extent() * 0.98f, -1.0f, -1.0f, 2.0f));
 			right_overlay_.reset(new OpenGL::Rectangle(output_shader_program_->get_right_extent() * 0.98f, -1.0f, 1.0f, 2.0f));
 		}
 		output_shader_program_->bind();
@@ -238,6 +239,7 @@ void OpenGLOutputBuilder::draw_frame(unsigned int output_width, unsigned int out
 
 		// mask off the gutter
 		glDisable(GL_BLEND);
+		left_overlay_->draw(0.0, 0.0, 0.0);
 		right_overlay_->draw(0.0, 0.0, 0.0);
 	}
 
diff --git a/Outputs/CRT/Internals/CRTOpenGL.hpp b/Outputs/CRT/Internals/CRTOpenGL.hpp
index b0c554eff..c50ac4560 100644
--- a/Outputs/CRT/Internals/CRTOpenGL.hpp
+++ b/Outputs/CRT/Internals/CRTOpenGL.hpp
@@ -118,6 +118,7 @@ class OpenGLOutputBuilder {
 		// The fix: just always treat that area as invisible. This is acceptable thanks to
 		// the concept of overscan. One is allowed not to display extreme ends of the image.
 		std::unique_ptr<OpenGL::Rectangle> right_overlay_;
+		std::unique_ptr<OpenGL::Rectangle> left_overlay_;
 
 	public:
 		// These two are protected by output_mutex_.
diff --git a/Outputs/CRT/Internals/Shaders/OutputShader.cpp b/Outputs/CRT/Internals/Shaders/OutputShader.cpp
index bad5bc1d5..91ec8049a 100644
--- a/Outputs/CRT/Internals/Shaders/OutputShader.cpp
+++ b/Outputs/CRT/Internals/Shaders/OutputShader.cpp
@@ -96,6 +96,7 @@ void OutputShader::set_output_size(unsigned int output_width, unsigned int outpu
 	GLfloat outputAspectRatioMultiplier = (static_cast<float>(output_width) / static_cast<float>(output_height)) / (4.0f / 3.0f);
 	GLfloat bonusWidth = (outputAspectRatioMultiplier - 1.0f) * visible_area.size.width;
 
+	left_extent_ = (-1.0f / outputAspectRatioMultiplier) / visible_area.size.width;
 	right_extent_ = (1.0f / outputAspectRatioMultiplier) / visible_area.size.width;
 
 	visible_area.origin.x -= bonusWidth * 0.5f;
@@ -105,6 +106,10 @@ void OutputShader::set_output_size(unsigned int output_width, unsigned int outpu
 	set_uniform("boundsSize", (GLfloat)visible_area.size.width, (GLfloat)visible_area.size.height);
 }
 
+float OutputShader::get_left_extent() {
+	return left_extent_;
+}
+
 float OutputShader::get_right_extent() {
 	return right_extent_;
 }
diff --git a/Outputs/CRT/Internals/Shaders/OutputShader.hpp b/Outputs/CRT/Internals/Shaders/OutputShader.hpp
index 2ca65b572..5a43832d2 100644
--- a/Outputs/CRT/Internals/Shaders/OutputShader.hpp
+++ b/Outputs/CRT/Internals/Shaders/OutputShader.hpp
@@ -88,12 +88,18 @@ public:
 	*/
 	void set_input_width_scaler(float input_scaler);
 
+	/*!
+		@returns The location, in eye coordinates, of the left edge of the output area.
+	*/
+	float get_left_extent();
+
 	/*!
 		@returns The location, in eye coordinates, of the right edge of the output area.
 	*/
 	float get_right_extent();
 
 private:
+	float left_extent_ = 0.0f;
 	float right_extent_ = 0.0f;
 };