raisin::SkyAtmosphereSystem

class · #include <rayrai/SkyAtmosphereSystem.hpp>

Owner of the Hillaire sky-atmosphere LUT pipeline (transmittance, multi-scattering, sky-view, aerial-perspective volume).

Extracted from RayraiWindow as part of the 1.1 decomposition. Holds the GL handles for the four LUT textures and their FBOs; renders them on demand. Static LUTs (transmittance + multi-scattering) only re-render when markStaticLutsDirty() has been called or first allocation.

GL ownership: the destructor releases all owned GL handles via release(). Copy disabled per Rule of 5; this class manages raw GL resources that would be double-freed under shallow copy.

Constructors & destructor

SkyAtmosphereSystem

SkyAtmosphereSystem() = default

SkyAtmosphereSystem(const SkyAtmosphereSystem &) = delete

SkyAtmosphereSystem(SkyAtmosphereSystem &&) = delete

~SkyAtmosphereSystem

~SkyAtmosphereSystem()

Public member functions

operator=

SkyAtmosphereSystem &operator=(const SkyAtmosphereSystem &) = delete

SkyAtmosphereSystem &operator=(SkyAtmosphereSystem &&) = delete

ensureResources

bool ensureResources()

Lazily allocate FBOs + textures for the four LUTs.

Returns true on success; throws if a required framebuffer is incomplete.

release

void release()

Release all owned GL handles. Safe to call multiple times.

render

void render(
    Shader &transmittanceShader,
    Shader &multiScatShader,
    Shader &skyViewShader,
    Shader *apShader,
    unsigned int fullScreenVao,
    const glm::vec3 &sunDirectionHillaire,
    float cameraHeightKm,
    const glm::mat4 &invViewMat,
    const glm::mat4 &invProjMat,
    bool aerialPerspectiveRequired)

Render the sky-atmosphere LUTs. Snapshots and restores the caller's framebuffer + viewport binding so the calling pass is unaffected.

Returns without GL work when no LUT is dirty and the sun direction, camera height (and, for the aerial-perspective volume, camera matrices) match the previous render. Allocates resources on demand.

Parameters

Parameter	Description
transmittanceShader	shader to bind for the transmittance LUT pass
multiScatShader	shader for the multi-scatter LUT pass
skyViewShader	shader for the sky-view LUT pass
apShader	shader for the aerial-perspective volume pass; nullable when disabled
fullScreenVao	VAO with a full-screen triangle (gl_VertexID-driven)
sunDirectionHillaire	direction TO the sun in world space (Hillaire convention)
cameraHeightKm	altitude of the camera above ground in km
invViewMat	inverse of the scene camera's view matrix
invProjMat	inverse of the scene camera's projection matrix
aerialPerspectiveRequired	whether the aerial-perspective volume is sampled this frame

markStaticLutsDirty

void markStaticLutsDirty()

Force the static LUTs (transmittance, multi-scattering) to be recomputed on the next render. Call when atmosphere parameters change. The sky-view and aerial-perspective LUTs are invalidated too.

transmittanceLut

unsigned int transmittanceLut() const

LUT texture handle accessors. Zero means not yet allocated.

Returns Transmittance LUT (256x64).

multiScatLut

unsigned int multiScatLut() const

Returns Multi-scattering LUT (32x32).

skyViewLut

unsigned int skyViewLut() const

Returns Sky-view LUT (192x108).

aerialPerspectiveLut

unsigned int aerialPerspectiveLut() const

Returns Aerial-perspective volume (32x32x32 RGBA16F).

Static member functions

uploadEarthAtmosphereUniforms static

static void uploadEarthAtmosphereUniforms(Shader &sh)

Bind the standard Hillaire Earth atmosphere parameters as uniforms on sh. Exposed so the final consumer (skybox / post) can upload the same parameters with one helper.

Parameters

Parameter	Description
sh	Shader to receive the uniforms.