feat(shapes): Add shapes_mouse_trail.c example and screenshot (#5246)

Co-authored-by: Balamurugan R <balamuruga.r050814@gmail.com>

examples/shapes/shapes_mouse_trail.c

@@ -0,0 +1,106 @@
+#include "raylib.h"
+#include "raymath.h"
+
+/*******************************************************************************************
+*
+* raylib [shapes] example - Draw a mouse trail (position history)
+*
+* Example complexity rating: [★☆☆☆] 1/4
+*
+* Example originally created with raylib 5.6
+*
+* Example contributed by [Balamurugan R] (@[Bala050814]]) and reviewed by [Ray] (@raysan5)
+*
+* Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+* BSD-like license that allows static linking with closed source software
+*
+* Copyright (c) 2024 [Balamurugan R] (@[Bala050814])
+*
+********************************************************************************************/
+
+// Define the maximum number of positions to store in the trail
+#define MAX_TRAIL_LENGTH 30
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [shapes] example - Draw a mouse trail");
+
+    // Array to store the history of mouse positions (our fixed-size queue)
+    Vector2 trailPositions[MAX_TRAIL_LENGTH] = { 0 }; 
+
+    SetTargetFPS(60);
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        Vector2 mousePosition = GetMousePosition();
+
+        // 1. Shift all existing positions backward by one slot in the array
+        // The last element (the oldest position) is dropped.
+        for (int i = MAX_TRAIL_LENGTH - 1; i > 0; i--)
+        {
+            trailPositions[i] = trailPositions[i - 1];
+        }
+
+        // 2. Store the new, current mouse position at the start of the array (Index 0)
+        trailPositions[0] = mousePosition;
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            // Use BLACK for a darker background to make the colored trail pop
+            ClearBackground(BLACK); 
+            
+            // 3. Draw the trail by looping through the history array
+            for (int i = 0; i < MAX_TRAIL_LENGTH; i++)
+            {
+                // Ensure we skip drawing if the array hasn't been fully filled on startup
+                if (trailPositions[i].x != 0.0f || trailPositions[i].y != 0.0f)
+                {
+                    // Calculate relative trail strength (ratio is near 1.0 for new, near 0.0 for old)
+                    float ratio = (float)(MAX_TRAIL_LENGTH - i) / MAX_TRAIL_LENGTH; 
+                    
+                    // Fade effect: oldest positions are more transparent
+                    // Fade (color, alpha) - alpha is 0.5 to 1.0 based on ratio
+                    Color trailColor = Fade(SKYBLUE, ratio * 0.5f + 0.5f); 
+                    
+                    // Size effect: oldest positions are smaller
+                    float trailRadius = 15.0f * ratio; 
+                    
+                    DrawCircleV(trailPositions[i], trailRadius, trailColor);
+                }
+            }
+
+            // Draw a distinct white circle for the current mouse position (Index 0)
+            DrawCircleV(mousePosition, 15.0f, WHITE);
+            
+            DrawText("Move the mouse to see the trail effect!", 
+                     10, screenHeight - 30, 20, LIGHTGRAY);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+
+    // No resources loaded, nothing to unload.
+
+    CloseWindow();         // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}