feat: prevent reversing directly into snake neck and play denied sound effect

source/game_audio.cpp

@@ -14,6 +14,7 @@ void audio_setup(AudioContext &audio) {
     mmLoadEffect(SFX_167126__CRISSTANZA__UNPAUSE);
     mmLoadEffect(SFX_273792__PACOMAV__PLOP);
     mmLoadEffect(SFX_73750__TIMBRE__REMIX_OF_BENBONCAN_SAD_TROMBONE_MORE_WAH_BRIGHT_DE_CLICKED);
+    mmLoadEffect(SFX_DENIED);
 
     audio.sfx_pickup = {
         { SFX_332629__TREASURESOUNDS__ITEM_PICKUP },
@@ -62,6 +63,14 @@ void audio_setup(AudioContext &audio) {
         255,
         128,
     };
+
+    audio.sfx_denied = {
+        { SFX_DENIED },
+        static_cast<int>(1.0F * (1 << 10)),
+        5,
+        160,
+        128,
+    };
 }
 
 void audio_start_music(const AudioContext &audio) {
@@ -111,6 +120,10 @@ void audio_play_fail(const AudioContext &audio) {
     mmEffectEx(&audio.sfx_fail);
 }
 
+void audio_play_denied(const AudioContext &audio) {
+    mmEffectEx(&audio.sfx_denied);
+}
+
 bool audio_toggle_music(AudioContext &audio) {
     audio.musicEnabled = !audio.musicEnabled;
 

source/game_input.cpp

@@ -4,6 +4,8 @@
 #include <cstdint>
 #include <cstdio>
 
+#include "consts.h"
+
 bool handle_input_frame(InputContext &ctx) {
     scanKeys();
     const uint32_t keys = keysDown();
@@ -69,25 +71,76 @@ bool handle_input_frame(InputContext &ctx) {
 
     if (!ctx.state->paused && !ctx.state->gameOver) {
         const bool cursed = ctx.state->curseTicksRemaining > 0;
+        uint16_t requested_dir = 0;
+        bool has_dir_input = false;
 
         if ((keys != 0U) && ((keys & KEY_UP) != 0U)) {
-            ctx.state->snakeDirection = cursed ? 2 : 0;
-            draw_game(*ctx.state, *ctx.renderAssets);
+            requested_dir = cursed ? 2 : 0;
+            has_dir_input = true;
+        } else if ((keys != 0U) && ((keys & KEY_RIGHT) != 0U)) {
+            requested_dir = cursed ? 3 : 1;
+            has_dir_input = true;
+        } else if ((keys != 0U) && ((keys & KEY_DOWN) != 0U)) {
+            requested_dir = cursed ? 0 : 2;
+            has_dir_input = true;
+        } else if ((keys != 0U) && ((keys & KEY_LEFT) != 0U)) {
+            requested_dir = cursed ? 1 : 3;
+            has_dir_input = true;
         }
 
-        if ((keys != 0U) && ((keys & KEY_RIGHT) != 0U)) {
-            ctx.state->snakeDirection = cursed ? 3 : 1;
-            draw_game(*ctx.state, *ctx.renderAssets);
-        }
+        if (has_dir_input) {
+            bool is_reversing = false;
 
-        if ((keys != 0U) && ((keys & KEY_DOWN) != 0U)) {
-            ctx.state->snakeDirection = cursed ? 0 : 2;
-            draw_game(*ctx.state, *ctx.renderAssets);
-        }
+            if (ctx.state->snake.size() >= 2) {
+                const auto &head = ctx.state->snake.front();
+                const auto &neck = ctx.state->snake.at(1);
+                int next_x = head[0];
+                int next_y = head[1];
 
-        if ((keys != 0U) && ((keys & KEY_LEFT) != 0U)) {
-            ctx.state->snakeDirection = cursed ? 1 : 3;
-            draw_game(*ctx.state, *ctx.renderAssets);
+                switch (requested_dir) {
+                case 0:
+                    next_y--;
+                    break;
+                case 1:
+                    next_x++;
+                    break;
+                case 2:
+                    next_y++;
+                    break;
+                case 3:
+                    next_x--;
+                    break;
+                default:
+                    break;
+                }
+
+                if (next_x > X_MAX) {
+                    next_x = 0;
+                } else if (next_x < 0) {
+                    next_x = X_MAX;
+                }
+
+                if (next_y > Y_MAX) {
+                    next_y = 0;
+                } else if (next_y < 0) {
+                    next_y = Y_MAX;
+                }
+
+                if (next_x == neck[0] && next_y == neck[1]) {
+                    is_reversing = true;
+                }
+            } else {
+                if ((ctx.state->snakeDirection + 2) % 4 == requested_dir) {
+                    is_reversing = true;
+                }
+            }
+
+            if (is_reversing) {
+                audio_play_denied(*ctx.audio);
+            } else if (ctx.state->snakeDirection != requested_dir) {
+                ctx.state->snakeDirection = requested_dir;
+                draw_game(*ctx.state, *ctx.renderAssets);
+            }
         }
     }
 

source/main.cpp

@@ -175,7 +175,7 @@ void do_tick() {
 void init_game() {
 	
 	if (hardMode) {
-		timerStart(0, ClockDivider_1024, TIMER_FREQ_1024(9), do_tick);
+		timerStart(0, ClockDivider_1024, static_cast<uint16_t>(TIMER_FREQ_1024(9)), do_tick);
 		setBackdropColorSub(RGB15(10,5,5));
 		score = 0;
 		snakelength = START_LENGTH_HARD;
@@ -197,7 +197,7 @@ void init_game() {
 	} 
 	else
 	{
-		timerStart(0, ClockDivider_1024, TIMER_FREQ_1024(5), do_tick);
+		timerStart(0, ClockDivider_1024, static_cast<uint16_t>(TIMER_FREQ_1024(5)), do_tick);
 		setBackdropColorSub(RGB15(5,5,5));
 		score = 0;
 		snakelength = START_LENGTH;