move typedefs to twn_types.h, specify that twn_vec.h is C user only, remove Vec2sh

include/twn_types.h

@@ -39,4 +39,42 @@ typedef struct Matrix4 {
     Vec4 row[4];
 } Matrix4;
 
+
+/* a point in some space (integer) */
+typedef struct Vec2i {
+_Alignas(8)
+    int32_t x;
+    int32_t y;
+} Vec2i;
+
+
+/* a point in some space (floating point) */
+typedef struct Vec2 {
+_Alignas(8)
+    float x;
+    float y;
+} Vec2;
+
+
+/* a point in some three dimension space (floating point) */
+/* y goes up, x goes to the right */
+typedef struct Vec3 {
+_Alignas(16)
+    float x;
+    float y;
+    float z;
+} Vec3;
+
+
+/* a point in some three dimension space (floating point) */
+/* y goes up, x goes to the right */
+typedef struct Vec4 {
+_Alignas(16)
+    float x;
+    float y;
+    float z;
+    float w;
+} Vec4;
+
+
 #endif