From 5a4d656cde78ce08fd19087f2e9817c1e46349a5 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 28 Jan 2026 14:41:46 -0500
Subject: [PATCH] Enable vertex attributes.

---
 Outputs/OpenGL/CompositionShader.cpp | 60 +++++++++++++++++++++++++++-
 1 file changed, 58 insertions(+), 2 deletions(-)

diff --git a/Outputs/OpenGL/CompositionShader.cpp b/Outputs/OpenGL/CompositionShader.cpp
index c77be5c48..778e792f3 100644
--- a/Outputs/OpenGL/CompositionShader.cpp
+++ b/Outputs/OpenGL/CompositionShader.cpp
@@ -7,6 +7,7 @@
 //
 
 #include "CompositionShader.hpp"
+#include "Outputs/ScanTargets/BufferingScanTarget.hpp"
 
 namespace {
 
@@ -369,6 +370,61 @@ OpenGL::Shader OpenGL::composition_shader(
 		prefix + fragment_shader
 	);
 
-	// TODO: bind inputs to match ScanTarget::Scan.
-	return std::move(shader);
+#define rt_offset_of(field) reinterpret_cast<void *>((reinterpret_cast<uint8_t *>(&scan.field) - reinterpret_cast<uint8_t *>(&scan)))
+	BufferingScanTarget::Scan scan;
+
+	for(int c = 0; c < 2; c++) {
+		const std::string endpoint = std::string("scanEndpoint") + std::to_string(c);
+
+		shader.enable_vertex_attribute_with_pointer(
+			endpoint + "DataOffset",
+			1, GL_UNSIGNED_SHORT, GL_FALSE,
+			sizeof(scan),
+			rt_offset_of(scan.end_points[c].data_offset),
+			1
+		);
+
+		shader.enable_vertex_attribute_with_pointer(
+			endpoint + "CyclesSinceRetrace",
+			1, GL_UNSIGNED_SHORT, GL_FALSE,
+			sizeof(scan),
+			rt_offset_of(scan.end_points[c].cycles_since_end_of_horizontal_retrace),
+			1
+		);
+
+		shader.enable_vertex_attribute_with_pointer(
+			endpoint + "CompositeAngle",
+			1, GL_UNSIGNED_BYTE, GL_FALSE,
+			sizeof(scan),
+			rt_offset_of(scan.end_points[c].cycles_since_end_of_horizontal_retrace),
+			1
+		);
+	}
+
+	shader.enable_vertex_attribute_with_pointer(
+		"scanDataY",
+		1, GL_UNSIGNED_SHORT, GL_FALSE,
+		sizeof(scan),
+		rt_offset_of(data_y),
+		1
+	);
+
+	shader.enable_vertex_attribute_with_pointer(
+		"scanLine",
+		1, GL_UNSIGNED_SHORT, GL_FALSE,
+		sizeof(scan),
+		rt_offset_of(line),
+		1
+	);
+
+	shader.enable_vertex_attribute_with_pointer(
+		"scanCompositeAmplitude",
+		1, GL_UNSIGNED_BYTE, GL_FALSE,
+		sizeof(scan),
+		rt_offset_of(scan.composite_amplitude),
+		1
+	);
+#undef rt_offset_of
+
+	return shader;
 }