From 5e0233646ef0170e54dfd9c9b991ffdc7674ba84 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan.goodliffe@octal.co.uk>
Date: Wed, 19 Apr 2023 14:48:04 +0100
Subject: Support setting vertex attrib divisor

---
 gfx/gl/vertexArrayObject.hpp | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/gfx/gl/vertexArrayObject.hpp b/gfx/gl/vertexArrayObject.hpp
index 92e0325..7ded03e 100644
--- a/gfx/gl/vertexArrayObject.hpp
+++ b/gfx/gl/vertexArrayObject.hpp
@@ -31,18 +31,18 @@ public:
 
 	template<typename VertexT, MP... attribs>
 	VertexArrayObject &
-	addAttribs(const GLuint arrayBuffer, const SequentialCollection<VertexT> auto & vertices)
+	addAttribs(const GLuint arrayBuffer, const SequentialCollection<VertexT> auto & vertices, const GLuint divisor = 0)
 	{
-		addAttribs<VertexT, attribs...>(arrayBuffer);
+		addAttribs<VertexT, attribs...>(arrayBuffer, divisor);
 		data(vertices, arrayBuffer, GL_ARRAY_BUFFER);
 		return *this;
 	}
 
 	template<typename VertexT, MP... attribs>
 	VertexArrayObject &
-	addAttribs(const GLuint arrayBuffer)
+	addAttribs(const GLuint arrayBuffer, const GLuint divisor = 0)
 	{
-		configure_attribs<VertexT, attribs...>(arrayBuffer);
+		configure_attribs<VertexT, attribs...>(arrayBuffer, divisor);
 		return *this;
 	}
 
@@ -73,34 +73,35 @@ public:
 private:
 	template<typename VertexT, typename T>
 	static auto
-	set_pointer(const GLuint vertexArrayId, const void * ptr)
+	set_pointer(const GLuint vertexArrayId, const void * ptr, const GLuint divisor)
 	{
 		using traits = gl_traits<T>;
 		const auto usedAttribs
 				= traits::vertexAttribFunc(vertexArrayId, traits::size, traits::type, sizeof(VertexT), ptr);
 		for (GLuint i {}; i < usedAttribs; i++) {
 			glEnableVertexAttribArray(vertexArrayId + i);
+			glVertexAttribDivisor(vertexArrayId + i, divisor);
 		}
 		return usedAttribs;
 	}
 
 	template<typename VertexT, MP attrib>
 	static auto
-	set_pointer(const GLuint vertexArrayId)
+	set_pointer(const GLuint vertexArrayId, const GLuint divisor)
 	{
-		return set_pointer<VertexT, typename decltype(attrib)::value_type>(vertexArrayId, attrib);
+		return set_pointer<VertexT, typename decltype(attrib)::value_type>(vertexArrayId, attrib, divisor);
 	}
 
 	template<typename VertexT, MP... attribs>
 	void
-	configure_attribs(const GLuint arrayBuffer)
+	configure_attribs(const GLuint arrayBuffer, const GLuint divisor)
 	{
 		glBindBuffer(GL_ARRAY_BUFFER, arrayBuffer);
 		if constexpr (sizeof...(attribs) == 0) {
-			vertexArrayId += set_pointer<VertexT, VertexT>(vertexArrayId, nullptr);
+			vertexArrayId += set_pointer<VertexT, VertexT>(vertexArrayId, nullptr, divisor);
 		}
 		else {
-			((vertexArrayId += set_pointer<VertexT, attribs>(vertexArrayId)), ...);
+			((vertexArrayId += set_pointer<VertexT, attribs>(vertexArrayId, divisor)), ...);
 		}
 	}
 
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