added stars to gameplay grid

src/graphics/GameRenderer.cpp

@@ -6,6 +6,10 @@
 #include <array>
 #include <cmath>
 #include <cstdio>
+#include <random>
+#include <vector>
+
+namespace {
 
 // Color constants (copied from main.cpp)
 static const SDL_Color COLORS[] = {
@@ -218,6 +222,12 @@ void GameRenderer::renderPlayingState(
         SDL_RenderLine(renderer, gridX, lineY, gridX + GRID_W, lineY);
     }
 
+    Uint64 nowTicks = SDL_GetTicks();
+    float deltaSeconds = (g_lastSparkTick == 0) ? (1.0f / 60.0f) : static_cast<float>(nowTicks - g_lastSparkTick) / 1000.0f;
+    g_lastSparkTick = nowTicks;
+    updateSparks(std::max(0.0f, deltaSeconds));
+    drawSparks(renderer, gridX, gridY, finalBlockSize);
+    
     // Draw block statistics panel border
     drawRectWithOffset(statsX - 3 - contentOffsetX, statsY - 3 - contentOffsetY, statsW + 6, statsH + 6, {100, 120, 200, 255});
     drawRectWithOffset(statsX - contentOffsetX, statsY - contentOffsetY, statsW, statsH, {30, 35, 50, 255});

src/graphics/Starfield3D.cpp

@@ -137,16 +137,16 @@ void Starfield3D::update(float deltaTime) {
     }
 }
 
-void Starfield3D::drawStar(SDL_Renderer* renderer, float x, float y, int type) {
-    const SDL_Color& color = STAR_COLORS[type % COLOR_COUNT];
-    SDL_SetRenderDrawColor(renderer, color.r, color.g, color.b, color.a);
+void Starfield3D::drawStar(SDL_Renderer* renderer, float x, float y, SDL_Color color, float alphaScale) {
+    Uint8 alpha = static_cast<Uint8>(std::clamp(color.a * alphaScale, 0.0f, 255.0f));
+    SDL_SetRenderDrawColor(renderer, color.r, color.g, color.b, alpha);
     
     // Draw star as a small rectangle (1x1 pixel)
     SDL_FRect rect{x, y, 1.0f, 1.0f};
     SDL_RenderFillRect(renderer, &rect);
 }
 
-void Starfield3D::draw(SDL_Renderer* renderer) {
+void Starfield3D::draw(SDL_Renderer* renderer, float offsetX, float offsetY, float alphaScale, bool grayscale) {
     for (const Star3D& star : stars) {
         // Calculate perspective projection factor
         const float k = DEPTH_FACTOR / star.z;
@@ -158,7 +158,12 @@ void Starfield3D::draw(SDL_Renderer* renderer) {
         // Only draw stars that are within the viewport
         if (px >= 0.0f && px <= static_cast<float>(width) && 
             py >= 0.0f && py <= static_cast<float>(height)) {
-            drawStar(renderer, px, py, star.type);
+            SDL_Color baseColor = STAR_COLORS[star.type % COLOR_COUNT];
+            if (grayscale) {
+                Uint8 gray = static_cast<Uint8>(0.299f * baseColor.r + 0.587f * baseColor.g + 0.114f * baseColor.b);
+                baseColor.r = baseColor.g = baseColor.b = gray;
+            }
+            drawStar(renderer, px + offsetX, py + offsetY, baseColor, alphaScale);
         }
     }
 }

src/graphics/Starfield3D.h

@@ -13,7 +13,7 @@ public:
 
     void init(int width, int height, int starCount = 160);
     void update(float deltaTime);
-    void draw(SDL_Renderer* renderer);
+    void draw(SDL_Renderer* renderer, float offsetX = 0.0f, float offsetY = 0.0f, float alphaScale = 1.0f, bool grayscale = false);
     void resize(int width, int height);
 
 private:
@@ -32,7 +32,7 @@ private:
     void setRandomDirection(Star3D& star);
     float randomFloat(float min, float max);
     int randomRange(int min, int max);
-    void drawStar(SDL_Renderer* renderer, float x, float y, int type);
+    void drawStar(SDL_Renderer* renderer, float x, float y, SDL_Color color, float alphaScale);
 
     std::vector<Star3D> stars;
     int width{0}, height{0};

src/graphics/effects/Starfield3D.cpp

@@ -137,16 +137,16 @@ void Starfield3D::update(float deltaTime) {
     }
 }
 
-void Starfield3D::drawStar(SDL_Renderer* renderer, float x, float y, int type) {
-    const SDL_Color& color = STAR_COLORS[type % COLOR_COUNT];
-    SDL_SetRenderDrawColor(renderer, color.r, color.g, color.b, color.a);
+void Starfield3D::drawStar(SDL_Renderer* renderer, float x, float y, SDL_Color color, float alphaScale) {
+    Uint8 alpha = static_cast<Uint8>(std::clamp(color.a * alphaScale, 0.0f, 255.0f));
+    SDL_SetRenderDrawColor(renderer, color.r, color.g, color.b, alpha);
     
     // Draw star as a small rectangle (1x1 pixel)
     SDL_FRect rect{x, y, 1.0f, 1.0f};
     SDL_RenderFillRect(renderer, &rect);
 }
 
-void Starfield3D::draw(SDL_Renderer* renderer) {
+void Starfield3D::draw(SDL_Renderer* renderer, float offsetX, float offsetY, float alphaScale, bool grayscale) {
     for (const Star3D& star : stars) {
         // Calculate perspective projection factor
         const float k = DEPTH_FACTOR / star.z;
@@ -158,7 +158,12 @@ void Starfield3D::draw(SDL_Renderer* renderer) {
         // Only draw stars that are within the viewport
         if (px >= 0.0f && px <= static_cast<float>(width) && 
             py >= 0.0f && py <= static_cast<float>(height)) {
-            drawStar(renderer, px, py, star.type);
+            SDL_Color baseColor = STAR_COLORS[star.type % COLOR_COUNT];
+            if (grayscale) {
+                Uint8 gray = static_cast<Uint8>(0.299f * baseColor.r + 0.587f * baseColor.g + 0.114f * baseColor.b);
+                baseColor.r = baseColor.g = baseColor.b = gray;
+            }
+            drawStar(renderer, px + offsetX, py + offsetY, baseColor, alphaScale);
         }
     }
 }

src/graphics/effects/Starfield3D.h

@@ -13,7 +13,7 @@ public:
 
     void init(int width, int height, int starCount = 160);
     void update(float deltaTime);
-    void draw(SDL_Renderer* renderer);
+    void draw(SDL_Renderer* renderer, float offsetX = 0.0f, float offsetY = 0.0f, float alphaScale = 1.0f, bool grayscale = false);
     void resize(int width, int height);
 
 private:
@@ -32,7 +32,7 @@ private:
     void setRandomDirection(Star3D& star);
     float randomFloat(float min, float max);
     int randomRange(int min, int max);
-    void drawStar(SDL_Renderer* renderer, float x, float y, int type);
+    void drawStar(SDL_Renderer* renderer, float x, float y, SDL_Color color, float alphaScale);
 
     std::vector<Star3D> stars;
     int width{0}, height{0};

src/graphics/renderers/GameRenderer.cpp

@@ -10,6 +10,7 @@
 #include <random>
 #include <vector>
 #include "../../core/Settings.h"
+#include "../../graphics/effects/Starfield3D.h"
 
 namespace {
 struct ImpactSpark {
@@ -30,6 +31,9 @@ struct ActivePieceSmoothState {
 };
 
 ActivePieceSmoothState s_activePieceSmooth;
+
+Starfield3D s_inGridStarfield;
+bool s_starfieldInitialized = false;
 }
 
 // Color constants (copied from main.cpp)
@@ -251,6 +255,22 @@ void GameRenderer::renderPlayingState(
         SDL_RenderLine(renderer, gridX, lineY, gridX + GRID_W, lineY);
     }
 
+    if (!s_starfieldInitialized) {
+        s_inGridStarfield.init(static_cast<int>(GRID_W), static_cast<int>(GRID_H), 180);
+        s_starfieldInitialized = true;
+    } else {
+        s_inGridStarfield.resize(static_cast<int>(GRID_W), static_cast<int>(GRID_H));
+    }
+
+    const float deltaSeconds = std::clamp(static_cast<float>(sparkDeltaMs) / 1000.0f, 0.0f, 0.033f);
+    s_inGridStarfield.update(deltaSeconds);
+
+    SDL_BlendMode oldBlend = SDL_BLENDMODE_NONE;
+    SDL_GetRenderDrawBlendMode(renderer, &oldBlend);
+    SDL_SetRenderDrawBlendMode(renderer, SDL_BLENDMODE_BLEND);
+    s_inGridStarfield.draw(renderer, gridX, gridY, 0.22f, true);
+    SDL_SetRenderDrawBlendMode(renderer, oldBlend);
+    
     // Draw block statistics panel border
     drawRectWithOffset(statsX - 3 - contentOffsetX, statsY - 3 - contentOffsetY, statsW + 6, statsH + 6, {100, 120, 200, 255});
     drawRectWithOffset(statsX - contentOffsetX, statsY - contentOffsetY, statsW, statsH, {30, 35, 50, 255});