+#ifndef MSP_GL_CAMERA_BACKEND_H_
+#define MSP_GL_CAMERA_BACKEND_H_
+
+namespace Msp {
+namespace GL {
+
+class Matrix;
+
+class OpenGLCamera
+{
+protected:
+ static void adjust_projection_matrix(Matrix &) { }
+};
+
+using CameraBackend = OpenGLCamera;
+
+} // namespace GL
+} // namespace Msp
+
+#endif