From ace2e6acdce6ec5f3a6034b8ee64efdb6102a199 Mon Sep 17 00:00:00 2001
From: Gregor Klevze <gregor@klevze.si>
Date: Sun, 30 Nov 2025 16:30:47 +0100
Subject: [PATCH] updated stars in game play grid

---
 src/graphics/effects/Starfield3D.cpp    | 31 +++++++++++++++++++++--
 src/graphics/effects/Starfield3D.h      |  6 +++++
 src/graphics/renderers/GameRenderer.cpp | 33 +++++++++++++++++++++++++
 3 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/src/graphics/effects/Starfield3D.cpp b/src/graphics/effects/Starfield3D.cpp
index fa038c4..f452e2d 100644
--- a/src/graphics/effects/Starfield3D.cpp
+++ b/src/graphics/effects/Starfield3D.cpp
@@ -23,6 +23,22 @@ void Starfield3D::resize(int w, int h) {
     centerY = height * 0.5f;
 }
 
+void Starfield3D::setMagnetTarget(float localX, float localY, float strength) {
+    if (strength <= 0.0f) {
+        clearMagnetTarget();
+        return;
+    }
+    magnetActive = true;
+    magnetStrength = strength;
+    magnetX = std::clamp(localX, 0.0f, static_cast<float>(width));
+    magnetY = std::clamp(localY, 0.0f, static_cast<float>(height));
+}
+
+void Starfield3D::clearMagnetTarget() {
+    magnetActive = false;
+    magnetStrength = 0.0f;
+}
+
 float Starfield3D::randomFloat(float min, float max) {
     std::uniform_real_distribution<float> dist(min, max);
     return dist(rng);
@@ -147,13 +163,24 @@ void Starfield3D::drawStar(SDL_Renderer* renderer, float x, float y, SDL_Color c
 }
 
 void Starfield3D::draw(SDL_Renderer* renderer, float offsetX, float offsetY, float alphaScale, bool grayscale) {
+    const bool useMagnet = magnetActive && magnetStrength > 0.0f;
     for (const Star3D& star : stars) {
         // Calculate perspective projection factor
         const float k = DEPTH_FACTOR / star.z;
         
         // Calculate screen position with perspective
-        const float px = star.x * k + centerX;
-        const float py = star.y * k + centerY;
+        float px = star.x * k + centerX;
+        float py = star.y * k + centerY;
+
+        if (useMagnet) {
+            float dx = magnetX - px;
+            float dy = magnetY - py;
+            float dist = std::sqrt(dx * dx + dy * dy);
+            float pull = magnetStrength / (magnetStrength + dist + 1.0f);
+            pull = std::clamp(pull, 0.0f, 0.35f);
+            px += dx * pull;
+            py += dy * pull;
+        }
         
         // Only draw stars that are within the viewport
         if (px >= 0.0f && px <= static_cast<float>(width) && 
diff --git a/src/graphics/effects/Starfield3D.h b/src/graphics/effects/Starfield3D.h
index 3e03189..40c76dc 100644
--- a/src/graphics/effects/Starfield3D.h
+++ b/src/graphics/effects/Starfield3D.h
@@ -15,6 +15,8 @@ public:
     void update(float deltaTime);
     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);
+    void setMagnetTarget(float localX, float localY, float strength);
+    void clearMagnetTarget();
 
 private:
     struct Star3D {
@@ -37,6 +39,10 @@ private:
     std::vector<Star3D> stars;
     int width{0}, height{0};
     float centerX{0}, centerY{0};
+    bool magnetActive{false};
+    float magnetX{0.0f};
+    float magnetY{0.0f};
+    float magnetStrength{0.0f};
 
     // Random number generator
     std::mt19937 rng;
diff --git a/src/graphics/renderers/GameRenderer.cpp b/src/graphics/renderers/GameRenderer.cpp
index 6fb9fb5..8ef3cb1 100644
--- a/src/graphics/renderers/GameRenderer.cpp
+++ b/src/graphics/renderers/GameRenderer.cpp
@@ -265,6 +265,39 @@ void GameRenderer::renderPlayingState(
     const float deltaSeconds = std::clamp(static_cast<float>(sparkDeltaMs) / 1000.0f, 0.0f, 0.033f);
     s_inGridStarfield.update(deltaSeconds);
 
+    bool appliedMagnet = false;
+    if (game) {
+        const Game::Piece& activePiece = game->current();
+        const int pieceType = static_cast<int>(activePiece.type);
+        if (pieceType >= 0 && pieceType < PIECE_COUNT) {
+            float sumLocalX = 0.0f;
+            float sumLocalY = 0.0f;
+            int filledCells = 0;
+            for (int cy = 0; cy < 4; ++cy) {
+                for (int cx = 0; cx < 4; ++cx) {
+                    if (!Game::cellFilled(activePiece, cx, cy)) {
+                        continue;
+                    }
+                    sumLocalX += (activePiece.x + cx + 0.5f) * finalBlockSize;
+                    sumLocalY += (activePiece.y + cy + 0.5f) * finalBlockSize;
+                    ++filledCells;
+                }
+            }
+            if (filledCells > 0) {
+                float magnetLocalX = sumLocalX / static_cast<float>(filledCells);
+                float magnetLocalY = sumLocalY / static_cast<float>(filledCells);
+                magnetLocalX = std::clamp(magnetLocalX, 0.0f, GRID_W);
+                magnetLocalY = std::clamp(magnetLocalY, 0.0f, GRID_H);
+                const float magnetStrength = finalBlockSize * 2.2f;
+                s_inGridStarfield.setMagnetTarget(magnetLocalX, magnetLocalY, magnetStrength);
+                appliedMagnet = true;
+            }
+        }
+    }
+    if (!appliedMagnet) {
+        s_inGridStarfield.clearMagnetTarget();
+    }
+
     SDL_BlendMode oldBlend = SDL_BLENDMODE_NONE;
     SDL_GetRenderDrawBlendMode(renderer, &oldBlend);
     SDL_SetRenderDrawBlendMode(renderer, SDL_BLENDMODE_BLEND);