From 56d67a978b72901fe0936024632ce7cdde4a67ea Mon Sep 17 00:00:00 2001
From: Murray Stevenson <50844517+murraystevenson@users.noreply.github.com>
Date: Thu, 28 May 2026 21:13:24 -0700
Subject: [PATCH 1/2] IECoreGL : Restore GL 2.1 compatibility for macOS

This isn't ideal, but will allow the OpenGL Scene Viewer in Gaffer 1.7 to continue to work on macOS.
---
 Changes                          |  5 +++++
 glsl/IECoreGL/CurvesPrimitive.h  |  4 ++--
 src/IECoreGL/CurvesPrimitive.cpp | 11 +++++++----
 src/IECoreGL/Shader.cpp          |  6 +++---
 4 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/Changes b/Changes
index 854bcd7ea6..a51c1d4183 100644
--- a/Changes
+++ b/Changes
@@ -1,7 +1,12 @@
 10.7.x.x (relative to 10.7.0.0a10)
 ========
 
+Fixes
+-----
 
+- IECoreGL::Shader : Restored compatibility with OpenGL 2.1 in order to preserve macOS support [^1].
+
+[^1]: To be omitted from the notes for the final 10.7.0.0 release.
 
 10.7.0.0a10 (relative to 10.7.0.0a9)
 ===========
diff --git a/glsl/IECoreGL/CurvesPrimitive.h b/glsl/IECoreGL/CurvesPrimitive.h
index 6cfc6ffc44..a6469ed627 100644
--- a/glsl/IECoreGL/CurvesPrimitive.h
+++ b/glsl/IECoreGL/CurvesPrimitive.h
@@ -47,7 +47,7 @@
 	layout( lines_adjacency ) in;\
 	layout( line_strip, max_vertices = 10 ) out;\
 	\
-	in int geometryIsCurveEndPoint[];\
+	in float geometryIsCurveEndPoint[];\
 	\
 	uniform mat4x4 basis;\
 	uniform mat4x4 phantomBasis0;\
@@ -70,7 +70,7 @@
 	layout( lines_adjacency ) in;\
 	layout( triangle_strip, max_vertices = 20 ) out;\
 	\
-	in int geometryIsCurveEndPoint[];\
+	in float geometryIsCurveEndPoint[];\
 	\
 	uniform mat4x4 basis;\
 	uniform mat4x4 phantomBasis0;\
diff --git a/src/IECoreGL/CurvesPrimitive.cpp b/src/IECoreGL/CurvesPrimitive.cpp
index 0e374b61bf..f1e4cc638e 100644
--- a/src/IECoreGL/CurvesPrimitive.cpp
+++ b/src/IECoreGL/CurvesPrimitive.cpp
@@ -338,15 +338,18 @@ const Shader::Setup *CurvesPrimitive::shaderSetup( const Shader *shader, State *
 		// To handle "phantom vertices" in the geometry shader, we need to know which
 		// vertices correspond to the original endpoints of the curve. We do that using
 		// the `vertexIsCurveEndPoint` attribute.
-		IECore::IntVectorDataPtr isEndPointData = new IECore::IntVectorData();
-		vector<int> &isEndPoint = isEndPointData->writable();
+		/// \todo `vertexIsCurveEndPoint` is a float attribute only to maintain compatibility
+		/// with OpenGL 2.1. Use an int attribute once we we're able to move IECoreGL to
+		/// OpenGL 3.3 Core Profile.
+		IECore::FloatVectorDataPtr isEndPointData = new IECore::FloatVectorData();
+		vector<float> &isEndPoint = isEndPointData->writable();
 		isEndPoint.resize( m_memberData->points->readable().size(), 0 );
 
 		int i = 0;
 		for( auto c : m_memberData->vertsPerCurve->readable() )
 		{
-			isEndPoint[i] = 1;
-			isEndPoint[i+c-1] = 1;
+			isEndPoint[i] = 1.0f;
+			isEndPoint[i+c-1] = 1.0f;
 			i += c;
 		}
 		geometryShaderSetup->addVertexAttribute( "vertexIsCurveEndPoint", isEndPointData );
diff --git a/src/IECoreGL/Shader.cpp b/src/IECoreGL/Shader.cpp
index 24a281d64a..ebb2ac0361 100644
--- a/src/IECoreGL/Shader.cpp
+++ b/src/IECoreGL/Shader.cpp
@@ -970,7 +970,7 @@ const std::string &Shader::defaultVertexSource()
 {
 	static const string g_s = R"(
 
-		#version 150 compatibility
+		#version 120
 
 		#if __VERSION__ <= 120
 		#define in attribute
@@ -985,14 +985,14 @@ const std::string &Shader::defaultVertexSource()
 		in vec3 vertexN;
 		in vec2 vertexuv;
 		in vec3 vertexCs;
-		in int vertexIsCurveEndPoint;
+		in float vertexIsCurveEndPoint;
 
 		out vec3 geometryI;
 		out vec3 geometryP;
 		out vec3 geometryN;
 		out vec2 geometryuv;
 		out vec3 geometryCs;
-		out int geometryIsCurveEndPoint;
+		out float geometryIsCurveEndPoint;
 
 		out vec3 fragmentI;
 		out vec3 fragmentP;

From 0e2450e878dcdb08f1879603cfbef9a1e0e219c6 Mon Sep 17 00:00:00 2001
From: Murray Stevenson <50844517+murraystevenson@users.noreply.github.com>
Date: Thu, 28 May 2026 21:13:49 -0700
Subject: [PATCH 2/2] IECoreGL : Remove trailing semicolons from shaders

These were added with the conversion to raw string literals in cab67a2b2f92160c61f58eb77c3f3bad9197172d and lead to syntax errors when the shaders are compiled on macOS.
---
 src/IECoreGL/Shader.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/IECoreGL/Shader.cpp b/src/IECoreGL/Shader.cpp
index ebb2ac0361..b45ad92fcd 100644
--- a/src/IECoreGL/Shader.cpp
+++ b/src/IECoreGL/Shader.cpp
@@ -1063,7 +1063,7 @@ const std::string &Shader::defaultFragmentSource()
 			vec3 Nf = faceforward( fragmentN, -fragmentI, fragmentN );
 			float f = dot( normalize( fragmentI ), normalize(Nf) );
 			gl_FragColor = vec4( f * fragmentCs, 1 );
-		};
+		}
 
 	)";
 
@@ -1083,7 +1083,7 @@ const std::string &Shader::constantFragmentSource()
 		void main()
 		{
 			gl_FragColor = vec4( fragmentCs, 1 );
-		};
+		}
 
 	)";
 
@@ -1118,7 +1118,7 @@ const std::string &Shader::lambertFragmentSource()
 			vec3 Cdiffuse = ieDiffuse( fragmentP, n, Cl, L, gl_MaxLights );
 
 			gl_FragColor = vec4( Cdiffuse, 1.0 );
-		};
+		}
 
 	)";