Cleaner code, slight vector progress. dgray still doesn't work and I don't know why

include/init.h

@@ -1,7 +1,10 @@
 #ifndef _DEF_INIT
 #define _DEF_INIT
 
+#ifdef FX9860G
 #include <gint/gray.h>
+#endif /* FX9860G */
+
 void init();
 
 #endif

include/vec.h

@@ -0,0 +1,16 @@
+#ifndef _DEF_VEC2D
+#define _DEF_VEC2D
+
+typedef struct Vec
+{
+	int x;
+	int y;
+} Vec;
+
+/* apply a force on a vector */
+void vec_add(Vec *vector, Vec force);
+
+/* apply the opposite of a force on a vector */
+void vec_sub(Vec *vector, Vec force);
+
+#endif

include/vec2d.h

@@ -1,10 +0,0 @@
-#ifndef _DEF_VEC2D
-#define _DEF_VEC2D
-
-struct Vec2D
-{
-	int x;
-	int y;
-};
-
-#endif

src/init.c

@@ -1,9 +1,10 @@
 #include "init.h"
+#include <gint/gray.h>
 
 void init()
 {
 	#ifdef FX9860G
-	gray_start();
+    dgray(DGRAY_ON);
 	#endif /* FX9860G */
 	#ifdef FXCG50
 	#endif /* FXCG50*/

src/main.c

@@ -1,16 +1,14 @@
 #include <gint/display.h>
 #include <gint/keyboard.h>
 #include "init.h"
-#include "vec2d.h"
+#include "vec.h"
 
 int main(void)
 {
 	init(); /* initialise gint */
 
-	struct Vec2D vector_test = {
-		.x = 20,
-		.y = -50
-	};
+	Vec vector_test = {20, -50};
+	vec_add(&vector_test, (Vec){5, -10});
 	dclear(C_WHITE);
 	dprint(1, 1, C_BLACK, "vector_test: x = %d, y = %d", vector_test.x, vector_test.y);
 	dupdate();

src/vec.c

@@ -0,0 +1,13 @@
+#include "vec.h"
+
+void vec_add(Vec *vector, Vec force)
+{
+    vector->x += force.x;
+    vector->y += force.y;
+}
+
+void vec_sub(Vec *vector, Vec force)
+{
+    vector->x -= force.x;
+    vector->y -= force.y;
+}

src/vec2d.c

@@ -1 +0,0 @@
-#include "vec2d.h"