From 21459ac4c92b82f2a3eeb1d9a6b462726001084c Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Tue, 18 Apr 2023 00:08:18 +0100
Subject: Specialize vertexAttribFunc for matrices because there's an upper
 limit of size 4 on attrib pointers

---
 lib/gl_traits.hpp | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

(limited to 'lib')

diff --git a/lib/gl_traits.hpp b/lib/gl_traits.hpp
index e2e689d..10b42e5 100644
--- a/lib/gl_traits.hpp
+++ b/lib/gl_traits.hpp
@@ -11,20 +11,23 @@ struct gl_traits_base {
 };
 struct gl_traits_float : public gl_traits_base {
 	static constexpr auto vertexAttribFunc {
-			[](GLuint index, GLint size, GLenum type, GLsizei stride, const void * pointer) {
+			[](GLuint index, GLint size, GLenum type, GLsizei stride, const void * pointer) -> GLuint {
 				glVertexAttribPointer(index, size, type, GL_FALSE, stride, pointer);
+				return 1;
 			}};
 };
 struct gl_traits_longfloat : public gl_traits_base {
 	static constexpr auto vertexAttribFunc {
-			[](GLuint index, GLint size, GLenum type, GLsizei stride, const void * pointer) {
+			[](GLuint index, GLint size, GLenum type, GLsizei stride, const void * pointer) -> GLuint {
 				glVertexAttribLPointer(index, size, type, stride, pointer);
+				return 1;
 			}};
 };
 struct gl_traits_integer : public gl_traits_base {
 	static constexpr auto vertexAttribFunc {
-			[](GLuint index, GLint size, GLenum type, GLsizei stride, const void * pointer) {
+			[](GLuint index, GLint size, GLenum type, GLsizei stride, const void * pointer) -> GLuint {
 				glVertexAttribIPointer(index, size, type, stride, pointer);
+				return 1;
 			}};
 };
 template<> struct gl_traits<glm::f32> : public gl_traits_float {
@@ -63,4 +66,12 @@ template<glm::length_t L, typename T, glm::qualifier Q> struct gl_traits<glm::ve
 template<glm::length_t C, glm::length_t R, typename T, glm::qualifier Q>
 struct gl_traits<glm::mat<C, R, T, Q>> : public gl_traits<T> {
 	static constexpr GLint size {C * R};
+	static constexpr auto vertexAttribFunc {
+			[](GLuint index, GLint, GLenum type, GLsizei stride, const void * pointer) -> GLuint {
+				const auto m = static_cast<glm::mat<C, R, T, Q>>(pointer);
+				for (glm::length_t r = 0; r < R; r++) {
+					glVertexAttribPointer(index, C, type, GL_FALSE, stride, &m[r]);
+				}
+				return R;
+			}};
 };
-- 
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