environment.h

#pragma once
 
#include <cstdint>
#include <string>
 
#include <glm/glm.hpp>
 
#include "core/reflect.h"
 
namespace Vkm::Engine {

struct SkySettings {
    std::string hdrPath;                
    float       intensity  = 1.0f;      
    bool        showSkybox = true;      
 
    // A Rayleigh + Mie atmosphere baked into the IBL in place of hdrPath; on by
    // default so a scene is lit before it owns any assets.
    bool  procedural       = true;
    float sunIntensity     = 22.0f;  
    float rayleigh         = 1.0f;   
    float mie              = 1.0f;   
    float mieG             = 0.76f;  
    float sunAngularRadius = 0.02f;  
    float sunDiscIntensity = 15.0f;  
 
    // SkySystem aims the key light from these, so the drawn sun and the shadows agree.
    float sunElevation = 50.0f;  
    float sunAzimuth   = 30.0f;  
 
    // The key light's daylight end; SkySystem blends it with the moonlight, so
    // the Light's own colour and intensity are unused under the procedural sky.
    glm::vec3 lightColor     = {1.0f, 0.96f, 0.90f};  
    float     lightIntensity = 3.0f;                  

    static constexpr float MAX_MIE_G = 0.99f;
};

struct NightSkySettings {
    glm::vec3 radiance = {0.004f, 0.006f, 0.014f};
    float     moonTilt          = 15.0f;            
    float     moonAngularRadius = 0.03f;            
    float     moonIntensity     = 1.2f;             
    float     starIntensity     = 3.0f;             
    float     starDensity       = 140.0f;           
 
    // The key light aimed at the moon once the sun is down, so night has
    // direction, shadows and speculars.
    glm::vec3 moonlightColor     = {0.55f, 0.65f, 1.0f};
    float     moonlightIntensity = 0.12f;

    static constexpr float TWILIGHT_DEGREES = 8.0f;
};

struct FogSettings {
    bool      enabled       = false;
    float     density       = 0.03f;               
    float     height        = 5.0f;                
    float     heightFalloff = 0.15f;               
    float     anisotropy    = 0.7f;                
    glm::vec3 albedo        = {0.8f, 0.85f, 1.0f}; 
    uint32_t  resolutionX   = 160;                 
    uint32_t  resolutionY   = 90;                  
    uint32_t  resolutionZ   = 64;                  
    float     maxDistance   = 200.0f;

    static constexpr float MAX_ANISOTROPY = 0.95f;
 
    static constexpr uint32_t MIN_FROXELS = 16;   
    static constexpr uint32_t MAX_FROXELS = 512;  
    static constexpr uint32_t MAX_FROXEL_COUNT = 1u << 22;

    glm::uvec3 froxelGrid() const;
};

struct SkyAngles {
    float elevation = 0.0f;  
    float azimuth   = 0.0f;  
};

struct Environment {
    SkySettings      sky;
    NightSkySettings night;
    FogSettings      fog;

    SkyAngles sunAngles() const {
        return {sky.sunElevation, sky.sunAzimuth};
    }

    SkyAngles moonAngles() const {
        return {-sky.sunElevation + night.moonTilt, sky.sunAzimuth + 180.0f};
    }

    glm::vec3 sunDirection() const {
        const SkyAngles a = sunAngles();
        return directionFromAngles(a.elevation, a.azimuth);
    }

    glm::vec3 moonDirection() const {
        const SkyAngles a = moonAngles();
        return directionFromAngles(a.elevation, a.azimuth);
    }

    static glm::vec3 directionFromAngles(float elevationDeg, float azimuthDeg);
};
 
} // namespace Vkm::Engine
 
VKM_REFLECT_BEGIN(::Vkm::Engine::SkySettings)
    VKM_F(hdrPath)
    VKM_F(intensity)
    VKM_F(showSkybox)
    VKM_F(procedural)
    VKM_F(sunIntensity)
    VKM_F(rayleigh)
    VKM_F(mie)
    VKM_F(mieG)
    VKM_F(sunAngularRadius)
    VKM_F(sunDiscIntensity)
    VKM_F(sunElevation)
    VKM_F(sunAzimuth)
    VKM_F(lightColor)
    VKM_F(lightIntensity)
VKM_REFLECT_END()
 
VKM_REFLECT_BEGIN(::Vkm::Engine::NightSkySettings)
    VKM_F(radiance)
    VKM_F(moonTilt)
    VKM_F(moonAngularRadius)
    VKM_F(moonIntensity)
    VKM_F(starIntensity)
    VKM_F(starDensity)
    VKM_F(moonlightColor)
    VKM_F(moonlightIntensity)
VKM_REFLECT_END()
 
VKM_REFLECT_BEGIN(::Vkm::Engine::FogSettings)
    VKM_F(enabled)
    VKM_F(density)
    VKM_F(height)
    VKM_F(heightFalloff)
    VKM_F(anisotropy)
    VKM_F(albedo)
    VKM_F(resolutionX)
    VKM_F(resolutionY)
    VKM_F(resolutionZ)
    VKM_F(maxDistance)
VKM_REFLECT_END()
 
VKM_REFLECT_BEGIN(::Vkm::Engine::Environment)
    VKM_F(sky)
    VKM_F(night)
    VKM_F(fog)
VKM_REFLECT_END()