Fix the Clang-Tidy warnings flagged by Android Studio

app/src/main/cpp/common.h

@@ -34,10 +34,10 @@ enum FillStyle {
 // a shape. The renderer repacks these into per-instance vertex attributes
 // (InstanceData in vk_renderer.cpp) consumed by shape.vert/.frag.
 struct DrawCmd {
-    float mtx[4];   // m00, m01, m10, m11
-    float tx, ty;   // NDC translation
-    float color[4]; // r, g, b, a
-    float style;    // FillStyle (as float — goes straight into the instance attributes)
-    float seed;     // reserved per-draw parameter (unused by current styles)
-    int shape;
+    float mtx[4] = {};       // m00, m01, m10, m11
+    float tx = 0.0f, ty = 0.0f;   // NDC translation
+    float color[4] = {};     // r, g, b, a
+    float style = 0.0f;      // FillStyle (as float — goes straight into the instance attributes)
+    float seed = 0.0f;       // reserved per-draw parameter (unused by current styles)
+    int shape = 0;
 };

app/src/main/cpp/game.h

@@ -65,36 +65,42 @@ class Game {
     // One invader. Its world position derives from the formation origin plus
     // its (row, col) slot, so the whole wave marches as a unit.
     struct Alien {
-        int  row, col;
-        AlienType type;
-        bool alive;
+        int  row = 0, col = 0;
+        AlienType type = ALIEN_SQUID;
+        bool alive = false;
     };
-    struct Bullet  { float x, y, vx, vy; bool alive; };          // player laser, flies up
-    struct Bomb    { float x, y, vx, vy, wobble; bool alive; };  // alien laser, falls down
-    struct Saucer  { float x, y, vx; bool alive = false; };
+    // player laser, flies up
+    struct Bullet  { float x = 0.0f, y = 0.0f, vx = 0.0f, vy = 0.0f; bool alive = false; };
+    // alien laser, falls down
+    struct Bomb    { float x = 0.0f, y = 0.0f, vx = 0.0f, vy = 0.0f, wobble = 0.0f; bool alive = false; };
+    struct Saucer  { float x = 0.0f, y = 0.0f, vx = 0.0f; bool alive = false; };
     // Level-10 boss: a giant mothership drifting sinusoidally across the top,
     // lobbing bombs aimed at the player. Killing it wins the game.
     struct Boss {
         float t = 0.0f, x = 0.0f;
         int   hp = 0, maxHp = 0;
         bool  alive = false;
     };
-    struct PowerUp { float x, y, vy, rot, spin; PowerUpType type; bool alive; };
+    struct PowerUp {
+        float x = 0.0f, y = 0.0f, vy = 0.0f, rot = 0.0f, spin = 0.0f;
+        PowerUpType type = PU_SHIELD;
+        bool alive = false;
+    };
     struct Particle {
-        float x, y, vx, vy;
-        float rot, spin;
-        float t, maxLife, size;
-        float r, g, b;
-        bool alive;
+        float x = 0.0f, y = 0.0f, vx = 0.0f, vy = 0.0f;
+        float rot = 0.0f, spin = 0.0f;
+        float t = 0.0f, maxLife = 0.0f, size = 0.0f;
+        float r = 0.0f, g = 0.0f, b = 0.0f;
+        bool alive = false;
     };
     struct Explosion {
-        float x, y, radius;
-        float t, maxLife;
-        float cr, cg, cb;
-        bool alive;
+        float x = 0.0f, y = 0.0f, radius = 0.0f;
+        float t = 0.0f, maxLife = 0.0f;
+        float cr = 0.0f, cg = 0.0f, cb = 0.0f;
+        bool alive = false;
     };
-    struct Star { float x, y, size, phase; };
-    struct Pointer { bool active; float x, y; };
+    struct Star { float x = 0.0f, y = 0.0f, size = 0.0f, phase = 0.0f; };
+    struct Pointer { bool active = false; float x = 0.0f, y = 0.0f; };
     struct HighScore { long score = 0; int level = 0; };
 
     static const int kMaxScores = 5;
@@ -142,33 +148,33 @@ class Game {
     // style selects the fragment-shader fill (STYLE_FLAT default, STYLE_GLOW).
     void emit(std::vector<DrawCmd>& out, int shape, float wx, float wy,
               float sx, float sy, float rot, float r, float g, float b, float a,
-              float style = (float)STYLE_FLAT);
+              float style = (float)STYLE_FLAT) const;
     void drawDigit(std::vector<DrawCmd>& out, int d, float cx, float cy,
-                   float h, float r, float g, float b, float a);
+                   float h, float r, float g, float b, float a) const;
     void drawNumber(std::vector<DrawCmd>& out, int value, float leftX, float cy,
-                    float h, float r, float g, float b, float a);
+                    float h, float r, float g, float b, float a) const;
     void drawLetter(std::vector<DrawCmd>& out, char ch, float cx, float cy,
-                    float h, float r, float g, float b, float a);
+                    float h, float r, float g, float b, float a) const;
     void drawText(std::vector<DrawCmd>& out, const char* text, float cx, float cy,
-                  float h, float r, float g, float b, float a);
+                  float h, float r, float g, float b, float a) const;
     void drawShip(std::vector<DrawCmd>& out, float cx, float cy, float scale,
-                  float tilt, float alpha);
+                  float tilt, float alpha) const;
     void drawAlien(std::vector<DrawCmd>& out, const Alien& a, float cx, float cy,
-                   float alpha);
-    void drawPowerUpHUD(std::vector<DrawCmd>& out);
-    void drawBossHealthBar(std::vector<DrawCmd>& out);
-    void drawControlStrip(std::vector<DrawCmd>& out);
+                   float alpha) const;
+    void drawPowerUpHUD(std::vector<DrawCmd>& out) const;
+    void drawBossHealthBar(std::vector<DrawCmd>& out) const;
+    void drawControlStrip(std::vector<DrawCmd>& out) const;
     void drawGearIcon(std::vector<DrawCmd>& out, float cx, float cy, float size,
-                      float r, float g, float b, float a);
+                      float r, float g, float b, float a) const;
     void drawGlassesIcon(std::vector<DrawCmd>& out, float cx, float cy, float size,
-                         float r, float g, float b, float a);
-    void drawOnGlassesOverlay(std::vector<DrawCmd>& out);
-    void drawSettingsScreen(std::vector<DrawCmd>& out);
+                         float r, float g, float b, float a) const;
+    void drawOnGlassesOverlay(std::vector<DrawCmd>& out) const;
+    void drawSettingsScreen(std::vector<DrawCmd>& out) const;
     void loadSettings();
     void saveSettings();
     void updateAutoPlay(float dt);
     bool isGearTap(float px, float py) const;
-    int numDigits(int v) const;
+    static int numDigits(int v);
 
     // --- audio ---
     AudioEngine* audio_ = nullptr;

app/src/main/cpp/main.cpp

@@ -80,7 +80,7 @@ struct Engine {
 };
 
 static double now_s() {
-    struct timespec t;
+    struct timespec t{};
     clock_gettime(CLOCK_MONOTONIC, &t);
     return (double)t.tv_sec + (double)t.tv_nsec * 1e-9;
 }

app/src/main/cpp/test/audio_stub.cpp

@@ -2,7 +2,9 @@
 #include "audio.h"
 AudioEngine::AudioEngine() = default;
 AudioEngine::~AudioEngine() {}   // impl_ is always nullptr in stubs
-bool AudioEngine::init()              { return false; }
+// NOLINT below: the stub ignores `this`, but the real audio.cpp impl doesn't,
+// so the shared declaration in audio.h cannot be static.
+bool AudioEngine::init()              { return false; }  // NOLINT(readability-convert-member-functions-to-static)
 void AudioEngine::shutdown()          {}
 void AudioEngine::triggerLaser()      {}
 void AudioEngine::triggerExplosion()  {}

app/src/main/cpp/test/game_test.cpp

@@ -164,7 +164,7 @@ TEST(March, StaysWithinSideMargins) {
             // Centers reverse at asp - margin - halfWidth = asp - 0.053;
             // 0.05 leaves slack for a single frame of overshoot.
             ASSERT_LT(fabsf(g.alienXForTest(a)), aspect() - 0.05f)
-                << "alien " << a << " out of margin after " << (i + 1) * 0.1f << " s";
+                << "alien " << a << " out of margin after " << (float)(i + 1) * 0.1f << " s";
         }
     }
 }

app/src/main/cpp/vk_renderer.cpp

@@ -266,10 +266,10 @@ bool VkRenderer::createVertexBuffer() {
         for (int r = 0; r < h; r++) {
             for (int c = 0; c < w; c++) {
                 if (rows[r][c] != 'X') continue;
-                float x0 = -1.0f + 2.0f * c / w;
-                float x1 = -1.0f + 2.0f * (c + 1) / w;
-                float y0 = -1.0f + 2.0f * r / h;
-                float y1 = -1.0f + 2.0f * (r + 1) / h;
+                float x0 = -1.0f + 2.0f * (float)c / (float)w;
+                float x1 = -1.0f + 2.0f * (float)(c + 1) / (float)w;
+                float y0 = -1.0f + 2.0f * (float)r / (float)h;
+                float y1 = -1.0f + 2.0f * (float)(r + 1) / (float)h;
                 push(x0, y0); push(x1, y0); push(x1, y1);
                 push(x0, y0); push(x1, y1); push(x0, y1);
             }
@@ -773,10 +773,10 @@ void VkRenderer::recordCommandBuffer(VkCommandBuffer cb, uint32_t imageIndex,
     // Centered viewport, scaled by renderScale_ (1.0 = full surface). The
     // render pass has already cleared the whole framebuffer, so the surround
     // is clear-colour (black = transparent on AR lenses).
-    float vw = extent_.width * renderScale_;
-    float vh = extent_.height * renderScale_;
-    float vx = (extent_.width - vw) * 0.5f;
-    float vy = (extent_.height - vh) * 0.5f;
+    float vw = (float)extent_.width * renderScale_;
+    float vh = (float)extent_.height * renderScale_;
+    float vx = ((float)extent_.width - vw) * 0.5f;
+    float vy = ((float)extent_.height - vh) * 0.5f;
     VkViewport vpt{vx, vy, vw, vh, 0.0f, 1.0f};
     VkRect2D sc{{(int32_t)vx, (int32_t)vy}, {(uint32_t)vw, (uint32_t)vh}};
     vkCmdSetViewport(cb, 0, 1, &vpt);