Cursor Trail Effect

1#include <SDL.h>
2#include <cmath>
3#include <iostream>
4#include <vector>
5#include "Window.h"
6
7class CursorTrail {
8 public:
9  void Tick() {
10    // Get current mouse position
11    int MouseX, MouseY;
12    SDL_GetMouseState(&MouseX, &MouseY);
13
14    // Add new position to trail
15    TrailPoints.push_back({MouseX, MouseY});
16
17    // Remove old positions if trail is too long
18    while (TrailPoints.size() > MaxTrailLength) {
19      TrailPoints.erase(TrailPoints.begin());
20    }
21
22    // Print current trail for demonstration
23    PrintTrail();
24  }
25
26 private:
27  struct Point {
28    int X, Y;
29  };
30
31  static const size_t MaxTrailLength = 10;
32  std::vector<Point> TrailPoints;
33
34  void PrintTrail() {
35    std::cout << "Trail: ";
36    for (size_t i = 0; i < TrailPoints.size(); ++i) {
37      float Opacity = static_cast<float>(i)
38        / TrailPoints.size();
39      std::cout << "(" << TrailPoints[i].X
40        << "," << TrailPoints[i].Y << "|"
41        << std::round(Opacity * 100) << "%) ";
42    }
43    std::cout << "\n";
44  }
45};
46
47int main(int argc, char** argv) {
48  SDL_Init(SDL_INIT_VIDEO);
49  Window GameWindow;
50  CursorTrail Trail;
51  SDL_Event E;
52
53  while (true) {
54    while (SDL_PollEvent(&E)) {
55      // Handle other events...
56    }
57
58    Trail.Tick();
59    GameWindow.Update();
60  }
61
62  SDL_Quit();
63  return 0;
64}

1#include <SDL.h>
2#include <cmath>
3#include <vector>
4
5class AdvancedCursorTrail {
6 public:
7  void Tick() {
8    // Get current time and position
9    Uint32 CurrentTime = SDL_GetTicks();
10    int MouseX, MouseY;
11    SDL_GetMouseState(&MouseX, &MouseY);
12
13    // Only add new point if moved enough
14    if (TrailPoints.empty() ||
15      DistanceToLastPoint(MouseX, MouseY)
16        > MinDistance) {
17      TrailPoint NewPoint{
18        static_cast<float>(MouseX),
19        static_cast<float>(MouseY),
20        CurrentTime
21      };
22
23      TrailPoints.push_back(NewPoint);
24    }
25
26    // Remove expired points
27    while (!TrailPoints.empty() &&
28      CurrentTime - TrailPoints.front().Time
29        > TrailDuration
30    ) {
31      TrailPoints.erase(TrailPoints.begin());
32    }
33
34    // Smooth existing points
35    SmoothTrail();
36  }
37
38 private:
39  struct TrailPoint {
40    float X, Y;
41    Uint32 Time;
42  };
43
44  std::vector<TrailPoint> TrailPoints;
45  // Trail Duration in Milliseconds
46  static const Uint32 TrailDuration = 500;
47  static const float MinDistance = 5.0f;
48
49  float DistanceToLastPoint(int X, int Y) {
50    if (TrailPoints.empty()) {
51      return MinDistance + 1;
52    }
53
54    auto& Last = TrailPoints.back();
55    float DX = X - Last.X;
56    float DY = Y - Last.Y;
57    return std::sqrt(DX * DX + DY * DY);
58  }
59
60  void SmoothTrail() {
61    for (
62      size_t i = 1;
63      i < TrailPoints.size() - 1;
64      ++i
65    ) {
66      TrailPoints[i].X = (
67        TrailPoints[i - 1].X +
68        TrailPoints[i].X * 2 +
69        TrailPoints[i + 1].X
70      ) / 4;
71
72      TrailPoints[i].Y = (
73        TrailPoints[i - 1].Y +
74        TrailPoints[i].Y * 2 +
75        TrailPoints[i + 1].Y
76      ) / 4;
77    }
78  }
79};