add callbacks for mouse movement and mouse clicking

ffi/glfw-input.c

@@ -0,0 +1,25 @@
+#include "export.h"
+#include <GLFW/glfw3.h>
+
+int MOUSE_PRESSED = GLFW_PRESS;
+int MOUSE_RELEASED = GLFW_RELEASE;
+int LEFT_MOUSE_BUTTON = GLFW_MOUSE_BUTTON_1;
+
+// Calls function exported from SML 
+void mouseMoveCallback(GLFWwindow *window, double xpos, double ypos) {
+  mltonMouseMoveCallback((int)xpos, (int)ypos);
+}
+
+void mouseClickCallback(GLFWwindow *window, int button, int action, int mods) {
+  mltonMouseClickCallback(button, action);
+}
+
+// Call this from MLton to register key callback with GLFW.
+void setMouseMoveCallback(GLFWwindow *window) {
+  glfwSetCursorPosCallback(window, mouseMoveCallback);
+}
+
+void setMouseClickCallback(GLFWwindow *window) {
+  glfwSetMouseButtonCallback(window, mouseClickCallback);
+}
+