parts: only render on PE_Update/PE_UpdateParts

Also, fix an issue in Rance 01 where a bad frame would be displayed when
loading a save (this is a bug present in the original game).

src/parts/parts.c

@@ -957,7 +957,7 @@ void PE_Update(int passed_time, bool message_window_show)
 	audio_update();
 	parts_update_animation(passed_time);
 	PE_UpdateInputState(passed_time);
-	parts_engine_dirty();
+	parts_render_update(passed_time);
 }
 
 void PE_UpdateParts(int passed_time, possibly_unused bool is_skip, bool message_window_show)
@@ -965,7 +965,7 @@ void PE_UpdateParts(int passed_time, possibly_unused bool is_skip, bool message_
 	parts_message_window_show = message_window_show;
 	audio_update();
 	parts_update_animation(passed_time);
-	parts_engine_dirty();
+	parts_render_update(passed_time);
 }
 
 void PE_SetDelegateIndex(int parts_no, int delegate_index)

src/parts/parts_internal.h

@@ -360,7 +360,9 @@ struct string *parts_text_get(struct parts_text *t);
 
 // render.c
 void parts_render_init(void);
+void parts_render_update(int passed_time);
 void parts_engine_dirty(void);
+void parts_engine_clean(void);
 void parts_dirty(struct parts *parts);
 void parts_render(struct parts *parts);
 void parts_render_family(struct parts *parts);

src/parts/render.c

@@ -262,14 +262,35 @@ void parts_engine_render(possibly_unused struct sprite *_)
 	}
 }
 
+static bool pe_dirty = false;
+
+void parts_render_update(int passed_time)
+{
+	// XXX: hack for Rance 01 load issue
+	//      There is a bug in Rance 01 where a single bad frame is displayed after
+	//      loading a save. When this happens, the game passes a negative time delta
+	//      to PE_Update. We fix this issue by ignoring such calls.
+	if (passed_time < 0)
+		return;
+	if (pe_dirty) {
+		scene_sprite_dirty(&goat_sprite);
+		pe_dirty = false;
+	}
+}
+
 void parts_engine_dirty(void)
 {
-	scene_sprite_dirty(&goat_sprite);
+	pe_dirty = true;
+}
+
+void parts_engine_clean(void)
+{
+	pe_dirty = false;
 }
 
 void parts_dirty(possibly_unused struct parts *parts)
 {
-	parts_engine_dirty();
+	pe_dirty = true;
 }
 
 void parts_render_init(void)

src/parts/save.c

@@ -642,7 +642,6 @@ bool PE_Load(struct page **buffer)
 		load_parts(&r, version);
 	}
 
-	PE_UpdateComponent(0);
-
+	parts_engine_clean();
 	return true;
 }