twn_input: singleton rework, twn_control.h and fixes

include/twn_context.h

@@ -8,12 +8,20 @@
 #include <stdint.h>
 
 
+/* context that is valid for current frame */
+/* changes to it should not have an effect, unless specified */
+/* TODO: ensure the statement above */
 typedef struct Context {
-    InputState input;
+    /* you may read from and write to these from game code */
+    void *udata;
 
+    /* TODO: is it what we actually want? */
     int64_t delta_time; /* preserves real time frame delta with no manipilation */
     uint64_t tick_count;
 
+    Vec2i mouse_window_position;
+    Vec2i mouse_relative_position;
+
     /* set just once on startup */
     uint64_t random_seed;
 
@@ -21,14 +29,13 @@ typedef struct Context {
     /* use it to simulate low framerate (e.g. at 60 tps, set to 2 for 30 fps) */
     /* it can be changed at runtime; any resulting logic anomalies are bugs */
     unsigned int update_multiplicity;
+
+    /* TODO: use Vec2i? */
     int window_w;
     int window_h;
     int base_draw_w;
     int base_draw_h;
 
-    /* you may read from and write to these from game code */
-    void *udata;
-
     bool debug;
     bool is_running;
     bool window_size_has_changed;