From 3c1a805770fe8b3289a35b46ad471f1c38162be6 Mon Sep 17 00:00:00 2001
From: Lior Halphon <LIJI32@gmail.com>
Date: Sat, 23 Dec 2017 17:41:47 +0200
Subject: [PATCH] Frame blending

---
 SDL/gui.c  | 18 +++++++++++++++---
 SDL/gui.h  |  1 +
 SDL/main.c | 17 ++++++++++++++---
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/SDL/gui.c b/SDL/gui.c
index bbee0d8..3076ddd 100644
--- a/SDL/gui.c
+++ b/SDL/gui.c
@@ -47,7 +47,7 @@ void render_texture(void *pixels,  void *previous)
 
 configuration_t configuration =
 {
-    {   SDL_SCANCODE_RIGHT,
+    .keys = {   SDL_SCANCODE_RIGHT,
         SDL_SCANCODE_LEFT,
         SDL_SCANCODE_UP,
         SDL_SCANCODE_DOWN,
@@ -57,8 +57,9 @@ configuration_t configuration =
         SDL_SCANCODE_RETURN,
         SDL_SCANCODE_SPACE
     },
-    GB_COLOR_CORRECTION_EMULATE_HARDWARE,
-    GB_SDL_SCALING_INTEGER_FACTOR,
+    .color_correction_mode = GB_COLOR_CORRECTION_EMULATE_HARDWARE,
+    .scaling_mode = GB_SDL_SCALING_INTEGER_FACTOR,
+    .blend_frames = true
 };
 
 
@@ -383,10 +384,21 @@ static void return_to_root_menu(unsigned index)
     current_selection = 0;
 }
 
+static void toggle_blend_frames(unsigned index)
+{
+    configuration.blend_frames ^= true;
+}
+
+const char *blend_frames_string(unsigned index)
+{
+    return configuration.blend_frames? "Enabled" : "Disabled";
+}
+
 static const struct menu_item graphics_menu[] = {
     {"Scaling Mode:", cycle_scaling, current_scaling_mode, cycle_scaling_backwards},
     {"Scaling Filter:", cycle_filter, current_filter_name, cycle_filter_backwards},
     {"Color Correction:", cycle_color_correction, current_color_correction_mode, cycle_color_correction_backwards},
+    {"Blend Frames:", toggle_blend_frames, blend_frames_string, toggle_blend_frames},
     {"Back", return_to_root_menu},
     {NULL,}
 };
diff --git a/SDL/gui.h b/SDL/gui.h
index 5a7e94a..41ac374 100644
--- a/SDL/gui.h
+++ b/SDL/gui.h
@@ -35,6 +35,7 @@ typedef struct {
     SDL_Scancode keys[9];
     GB_color_correction_mode_t color_correction_mode;
     enum scaling_mode scaling_mode;
+    bool blend_frames;
     
     bool div_joystick;
     bool flip_joystick_bit_1;
diff --git a/SDL/main.c b/SDL/main.c
index bac5936..9df3e43 100755
--- a/SDL/main.c
+++ b/SDL/main.c
@@ -16,7 +16,9 @@
 GB_gameboy_t gb;
 static bool dmg = false;
 static bool paused = false;
-static uint32_t pixels[160*144];
+static uint32_t pixel_buffer_1[160*144], pixel_buffer_2[160*144];
+static uint32_t *active_pixel_buffer = pixel_buffer_1, *previous_pixel_buffer = pixel_buffer_2;
+
 
 static char *filename = NULL;
 static bool should_free_filename = false;
@@ -213,7 +215,16 @@ static void handle_events(GB_gameboy_t *gb)
 
 static void vblank(GB_gameboy_t *gb)
 {
-    render_texture(pixels, NULL);
+    if (configuration.blend_frames) {
+        render_texture(active_pixel_buffer, previous_pixel_buffer);
+        uint32_t *temp = active_pixel_buffer;
+        active_pixel_buffer = previous_pixel_buffer;
+        previous_pixel_buffer = temp;
+        GB_set_pixels_output(gb, active_pixel_buffer);
+    }
+    else {
+        render_texture(active_pixel_buffer, NULL);
+    }
     handle_events(gb);
 }
 
@@ -303,7 +314,7 @@ restart:
         }
         
         GB_set_vblank_callback(&gb, (GB_vblank_callback_t) vblank);
-        GB_set_pixels_output(&gb, pixels);
+        GB_set_pixels_output(&gb, active_pixel_buffer);
         GB_set_rgb_encode_callback(&gb, rgb_encode);
         GB_set_sample_rate(&gb, have_aspec.freq);
         GB_set_color_correction_mode(&gb, configuration.color_correction_mode);