Create Visual Effects with Gamma

1#include <SDL.h>
2#include <cmath>
3
4class DayNightCycle {
5  SDL_Window* Window;
6  float TimeOfDay{0.0f}; // 0.0 to 24.0
7
8public:
9  DayNightCycle(SDL_Window* W) : Window{W} {}
10
11  void Update(float DeltaTimeSeconds) {
12    // Progress time (1 game hour per
13    // real second)
14    TimeOfDay += DeltaTimeSeconds;
15    if (TimeOfDay >= 24.0f) TimeOfDay -= 24.0f;
16
17    // Calculate brightness based on time
18    float Brightness{CalculateBrightness()};
19    SDL_SetWindowBrightness(Window, Brightness);
20  }
21
22private:
23  float CalculateBrightness() {
24    // Brightest at noon (12.0), darkest at
25    // midnight (0.0/24.0)
26    float NormalizedTime{
27      std::abs(TimeOfDay - 12.0f) / 12.0f};
28
29    // Smooth transition using cosine
30    return 1.0f + 0.5f * std::cos(
31      NormalizedTime * 3.14159f);
32  }
33};

1#include <SDL.h>
2
3class LightningEffect {
4  SDL_Window* Window;
5  float DefaultBrightness{1.0f};
6  bool IsFlashing{false};
7  Uint32 FlashStartTime{0};
8
9 public:
10  LightningEffect(SDL_Window* W) : Window{W} {}
11
12  void TriggerLightning() {
13    if (!IsFlashing) {
14      IsFlashing = true;
15      FlashStartTime = SDL_GetTicks();
16      // Bright flash
17      SDL_SetWindowBrightness(Window, 2.0f);
18    }
19  }
20
21  void Update() {
22    if (IsFlashing) {
23      Uint32 ElapsedTime{
24        SDL_GetTicks() - FlashStartTime};
25
26      // Flash duration in ms
27      if (ElapsedTime > 100) {
28        IsFlashing = false;
29        SDL_SetWindowBrightness(
30          Window, DefaultBrightness);
31      }
32    }
33  }
34};

1#include <SDL.h>
2
3class ColorTemperature {
4  SDL_Window* Window;
5
6 public:
7  ColorTemperature(SDL_Window* W) : Window{W} {}
8
9  void SetTemperature(float Temperature) {
10    // Temperature range: 0.0 (cool) to 1.0 (warm)
11    Uint16 RedRamp[256];
12    Uint16 BlueRamp[256];
13
14    // Warmer colors emphasize red, reduce blue
15    // More red when warm
16    float RedGamma{2.0f - Temperature};
17    // Less blue when warm
18    float BlueGamma{1.0f + Temperature};
19
20    SDL_CalculateGammaRamp(RedGamma, RedRamp);
21    SDL_CalculateGammaRamp(BlueGamma, BlueRamp);
22
23    // Green stays neutral
24    Uint16 GreenRamp[256];
25    SDL_CalculateGammaRamp(1.0f, GreenRamp);
26
27    SDL_SetWindowGammaRamp(
28      Window, RedRamp, GreenRamp, BlueRamp);
29  }
30};