Allow hiding background/object "layers" (#422)

Cocoa/Document.m

@@ -1043,6 +1043,13 @@ static unsigned *multiplication_table_for_frequency(unsigned frequency)
     else if ([anItem action] == @selector(toggleCheats:)) {
         [(NSMenuItem*)anItem setState:GB_cheats_enabled(&gb)];
     }
+    else if ([anItem action] == @selector(toggleDisplayBackground:)) {
+        [(NSMenuItem*)anItem setState:!GB_is_background_rendering_disabled(&gb)];
+    }
+    else if ([anItem action] == @selector(toggleDisplayObjects:)) {
+        [(NSMenuItem*)anItem setState:!GB_is_object_rendering_disabled(&gb)];
+    }
+    
     return [super validateUserInterfaceItem:anItem];
 }
 
@@ -2307,4 +2314,14 @@ static unsigned *multiplication_table_for_frequency(unsigned frequency)
     [self.osdView displayText:@"Screenshot copied"];
 }
 
+- (IBAction)toggleDisplayBackground:(id)sender
+{
+    GB_set_background_rendering_disabled(&gb, !GB_is_background_rendering_disabled(&gb));
+}
+
+- (IBAction)toggleDisplayObjects:(id)sender
+{
+    GB_set_object_rendering_disabled(&gb, !GB_is_object_rendering_disabled(&gb));
+}
+
 @end

Cocoa/MainMenu.xib

@@ -456,6 +456,19 @@
                                 </connections>
                             </menuItem>
                             <menuItem isSeparatorItem="YES" id="M6n-8G-LZS"/>
+                            <menuItem title="Show Background and Window" state="on" id="yfD-Qd-zoz">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                                <connections>
+                                    <action selector="toggleDisplayBackground:" target="-1" id="p5b-1n-SPR"/>
+                                </connections>
+                            </menuItem>
+                            <menuItem title="Show Objects" state="on" id="OWx-a0-vQk">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                                <connections>
+                                    <action selector="toggleDisplayObjects:" target="-1" id="8ie-ey-739"/>
+                                </connections>
+                            </menuItem>
+                            <menuItem isSeparatorItem="YES" id="afI-BR-65k"/>
                             <menuItem title="Show Memory" id="UIa-n7-LSa">
                                 <modifierMask key="keyEquivalentModifierMask"/>
                                 <connections>

Core/display.c

@@ -522,8 +522,8 @@ static uint8_t data_for_tile_sel_glitch(GB_gameboy_t *gb, bool *should_use, bool
 
 static void render_pixel_if_possible(GB_gameboy_t *gb)
 {
-    GB_fifo_item_t *fifo_item = NULL;
-    GB_fifo_item_t *oam_fifo_item = NULL;
+    const GB_fifo_item_t *fifo_item = NULL;
+    const GB_fifo_item_t *oam_fifo_item = NULL;
     bool draw_oam = false;
     bool bg_enabled = true, bg_priority = false;
     
@@ -533,7 +533,7 @@ static void render_pixel_if_possible(GB_gameboy_t *gb)
         
         if (fifo_size(&gb->oam_fifo)) {
             oam_fifo_item = fifo_pop(&gb->oam_fifo);
-            if (oam_fifo_item->pixel && (gb->io_registers[GB_IO_LCDC] & 2)) {
+            if (oam_fifo_item->pixel && (gb->io_registers[GB_IO_LCDC] & 2) && unlikely(!gb->objects_disabled)) {
                 draw_oam = true;
                 bg_priority |= oam_fifo_item->bg_priority;
             }
@@ -559,6 +559,12 @@ static void render_pixel_if_possible(GB_gameboy_t *gb)
             bg_enabled = false;
         }
     }
+    
+    if (unlikely(gb->background_disabled)) {
+        bg_enabled = false;
+        static const GB_fifo_item_t empty_item = {0,};
+        fifo_item = &empty_item;
+    }
 
     uint8_t icd_pixel = 0;
     uint32_t *dest = NULL;
@@ -1624,3 +1630,24 @@ bool GB_is_odd_frame(GB_gameboy_t *gb)
 {
     return gb->is_odd_frame;
 }
+
+void GB_set_object_rendering_disabled(GB_gameboy_t *gb, bool disabled)
+{
+    gb->objects_disabled = disabled;
+}
+
+void GB_set_background_rendering_disabled(GB_gameboy_t *gb, bool disabled)
+{
+    gb->background_disabled = disabled;
+}
+
+bool GB_is_object_rendering_disabled(GB_gameboy_t *gb)
+{
+    return gb->objects_disabled;
+}
+
+bool GB_is_background_rendering_disabled(GB_gameboy_t *gb)
+{
+    return gb->background_disabled;
+}
+

Core/display.h

@@ -61,4 +61,11 @@ uint32_t GB_convert_rgb15(GB_gameboy_t *gb, uint16_t color, bool for_border);
 void GB_set_color_correction_mode(GB_gameboy_t *gb, GB_color_correction_mode_t mode);
 void GB_set_light_temperature(GB_gameboy_t *gb, double temperature);
 bool GB_is_odd_frame(GB_gameboy_t *gb);
+
+void GB_set_object_rendering_disabled(GB_gameboy_t *gb, bool disabled);
+void GB_set_background_rendering_disabled(GB_gameboy_t *gb, bool disabled);
+bool GB_is_object_rendering_disabled(GB_gameboy_t *gb);
+bool GB_is_background_rendering_disabled(GB_gameboy_t *gb);
+
+
 #endif /* display_h */

Core/gb.h

@@ -630,6 +630,8 @@ struct GB_gameboy_internal_s {
         GB_sgb_border_t borrowed_border;
         bool tried_loading_sgb_border;
         bool has_sgb_border;
+        bool objects_disabled;
+        bool background_disabled;
                
         /* Timing */
         uint64_t last_sync;