Smoothing Mouse Movement

1#include <SDL.h>
2#include <deque>
3#include <numeric>
4#include "Window.h"
5
6class MotionSmoother {
7public:
8  void AddSample(int x, int y) {
9    // Add new sample
10    Samples.push_back({x, y});
11
12    // Remove old samples if we exceed our window
13    while (Samples.size() > WindowSize) {
14      Samples.pop_front();
15    }
16  }
17
18  SDL_Point GetSmoothedMotion() {
19    if (Samples.empty()) { return {0, 0}; }
20
21    // Calculate moving average
22    int SumX{0};
23    int SumY{0};
24
25    for (const auto& Sample : Samples) {
26      SumX += Sample.x;
27      SumY += Sample.y;
28    }
29
30    return {
31      SumX / static_cast<int>(Samples.size()),
32      SumY / static_cast<int>(Samples.size())};
33  }
34
35private:
36  static constexpr size_t WindowSize{5};
37  std::deque<SDL_Point> Samples;
38};
39
40class Camera {
41public:
42  void Update(SDL_MouseMotionEvent& E) {
43    // Add new motion sample
44    Smoother.AddSample(E.xrel, E.yrel);
45
46    // Get smoothed motion
47    SDL_Point Motion{
48      Smoother.GetSmoothedMotion()};
49
50    // Apply smoothed motion
51    xRotation += Motion.x * Sensitivity;
52    yRotation += Motion.y * Sensitivity;
53
54    std::cout << "Raw input: " << E.xrel << ", "
55      << E.yrel << '\n'
56      << "Smoothed: " << Motion.x << ", "
57      << Motion.y << '\n';
58  }
59
60private:
61  MotionSmoother Smoother;
62  float xRotation{0.0f};
63  float yRotation{0.0f};
64  float Sensitivity{0.1f};
65};
66
67int main() {
68  SDL_Init(SDL_INIT_VIDEO);
69  Window GameWindow;
70  Camera Cam;
71  SDL_SetRelativeMouseMode(SDL_TRUE);
72
73  SDL_Event E;
74  while (true) {
75    while (SDL_PollEvent(&E)) {
76      if (E.type == SDL_MOUSEMOTION) {
77        Cam.Update(E.motion);
78      } else if (E.type == SDL_QUIT) {
79        SDL_Quit();
80        return 0;
81      }
82    }
83    GameWindow.Update();
84    GameWindow.Render();
85  }
86}