diff -r cef43609a374 -r 0133e565e072 src/matrix.h
--- a/src/matrix.h	Sat Dec 14 23:00:01 2019 +0200
+++ b/src/matrix.h	Wed Jan 01 17:45:56 2020 +0200
@@ -146,5 +146,7 @@
 	return stream;
 }
 
+Matrix4x4 combine(const Matrix3x3& topLeft, const struct Point3D& translation);
+
 static constexpr Matrix3x3 identity3x3 {{{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}};
 static constexpr Matrix4x4 identity4x4 {{{1, 0, 0, 0}, {0, 1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, 1}}};