Decompile window_rotate_camera, change sub_689174 to use z parameter

src/map.c

@@ -138,7 +138,9 @@ void map_update_tile_pointers()
 
 /**
  * Return the absolute height of an element, given its (x,y) coordinates
- * 
+ *  ax: x
+ *  cx: y
+ *  dx: return
  *  rct2: 0x00662783
  */
 int map_element_height(int x, int y)

src/viewport.c

@@ -221,8 +221,8 @@ void viewport_update_pointers()
 	*vp = NULL;
 }
 
-void sub_689174(sint16* x, sint16* y, uint8 curr_rotation){
-	//RCT2_CALLFUNC_X(0x00689174, (int*)&x, (int*)&y, &ecx, &curr_rotation, (int*)&window, (int*)&viewport, &ebp);
+void sub_689174(sint16* x, sint16* y, sint16 *z, uint8 curr_rotation){
+	//RCT2_CALLFUNC_X(0x00689174, (int*)&x, (int*)&y, (int*)&z, &curr_rotation, (int*)&window, (int*)&viewport, &ebp);
 
 	sint16 start_x = *x;
 	sint16 start_y = *y;
@@ -262,6 +262,7 @@ void sub_689174(sint16* x, sint16* y, uint8 curr_rotation){
 		}
 		break;
 	}
+	*z = height;
 }
 
 /**
@@ -296,11 +297,12 @@ void viewport_update_position(rct_window *window)
 
 	sint16 x = viewport->view_width / 2 + window->saved_view_x;
 	sint16 y = viewport->view_height / 2 + window->saved_view_y;
+	sint16 z;
 
 	int curr_rotation = RCT2_GLOBAL(RCT2_ADDRESS_CURRENT_ROTATION, uint32);
-	sub_689174(&x, &y, curr_rotation);
+	sub_689174(&x, &y, &z, curr_rotation);
 	
-	RCT2_CALLPROC_X(0x006E7A15, x, y, 0, 0, (int)window, (int)viewport, 0);
+	RCT2_CALLPROC_X(0x006E7A15, x, y, z, 0, (int)window, (int)viewport, 0);
 
 	//Clamp to the map minimum value
 	int at_map_edge = 0;

src/viewport.h

@@ -47,11 +47,14 @@ enum {
 extern rct_viewport* g_viewport_list;
 
 void viewport_init_all();
+void center_2d_coordinates(int x, int y, int z, int* out_x, int* out_y, rct_viewport* viewport);
 void viewport_create(rct_window *w, int x, int y, int width, int height, int zoom, int center_x, int center_y, int center_z, char flags, sint16 sprite);
 void viewport_update_pointers();
 void viewport_update_position(rct_window *window);
 void viewport_render(rct_drawpixelinfo *dpi, rct_viewport *viewport, int left, int top, int right, int bottom);
 
+void sub_689174(sint16* x, sint16* y, sint16 *z, uint8 curr_rotation);
+
 void screen_pos_to_map_pos(short *x, short *y);
 
 void show_gridlines();

src/window.c

@@ -21,7 +21,9 @@
 #include <string.h>
 #include "addresses.h"
 #include "audio.h"
+#include "game.h"
 #include "gfx.h"
+#include "map.h"
 #include "osinterface.h"
 #include "rct2.h"
 #include "widget.h"
@@ -963,7 +965,49 @@ void window_scroll_to_location(rct_window *w, int x, int y, int z)
  */
 void window_rotate_camera(rct_window *w)
 {
-	RCT2_CALLPROC_X(0x0068881A, 0, 0, 0, 0, (int)w, 0, 0);
+	//RCT2_CALLPROC_X(0x0068881A, 0, 0, 0, 0, (int)w, 0, 0);
+
+	rct_viewport *viewport = w->viewport;
+	if (viewport == NULL)
+		return;
+
+	sint16 x = (viewport->width >> 1) + viewport->x;
+	sint16 y = (viewport->height >> 1) + viewport->y;
+	sint16 z;
+
+	uint8 rot = RCT2_GLOBAL(RCT2_ADDRESS_CURRENT_ROTATION, uint8);
+
+	int ecx, edx, esi, edi = (int)viewport, ebp;
+	//has something to do with checking if middle of the viewport is obstructed
+	RCT2_CALLFUNC_X(0x00688972, (int*)&x, (int*)&y, &ecx, &edx, &esi, &edi, &ebp);
+	rct_viewport *other = (rct_viewport*)edi;
+
+	// other != viewport probably triggers on viewports in ride or guest window?
+	// x is 0x8000 if middle of viewport is obstructed by another window?
+	if (x == (sint16)SPRITE_LOCATION_NULL || other != viewport){
+		x = (viewport->view_width >> 1) + viewport->view_x;
+		y = (viewport->view_height >> 1) + viewport->view_y;
+
+		sub_689174(&x, &y, &z, rot);
+	} else {
+		z = map_element_height(x, y);
+	}
+
+	RCT2_GLOBAL(RCT2_ADDRESS_CURRENT_ROTATION, uint32) = (rot + 1) % 4;
+
+	int new_x, new_y;
+	center_2d_coordinates(x, y, z, &new_x, &new_y, viewport);
+
+	w->saved_view_x = new_x;
+	w->saved_view_y = new_y;
+	viewport->view_x = new_x;
+	viewport->view_y = new_y;
+
+	window_invalidate(w);
+
+	RCT2_CALLPROC_EBPSAFE(0x00688956);
+
+	sub_0x0069E9A7();
 }
 
 /**