--- /dev/null
+#ifndef MSP_GL_BLEND_BACKEND_H_
+#define MSP_GL_BLEND_BACKEND_H_
+
+#ifndef MSP_GL_BLEND_H_
+#error "blend_backend.h requires blend.h"
+#endif
+
+namespace Msp {
+namespace GL {
+
+unsigned get_vulkan_blend_equation(BlendEquation);
+unsigned get_vulkan_blend_factor(BlendFactor);
+unsigned get_vulkan_color_mask(ColorWriteMask);
+
+} // namespace GL
+} // namespace Msp
+
+#endif