#include <algorithm>
#include "sky_math.h"
#include "sky_nishita.h"

Classes
class	SkyMultipleScattering

Functions
float	molecular_phase_function (const float cos_theta)
float	aerosol_phase_function (const float cos_theta)
float4	get_molecular_scattering_coefficient (const float h)
float4	get_molecular_absorption_coefficient (const float h)
float	get_aerosol_density (const float h)
float3	spectral_to_xyz (const float4 L)
void	SKY_multiple_scattering_precompute_texture (float *pixels, int stride, int width, int height, float sun_elevation, float altitude, float air_density, float aerosol_density, float ozone_density)
void	SKY_multiple_scattering_precompute_sun (float sun_elevation, float angular_diameter, float altitude, float air_density, float aerosol_density, float ozone_density, float r_pixel_bottom[3], float r_pixel_top[3])
float	SKY_earth_intersection_angle (float altitude)

Variables
static const float4	GROUND_ALBEDO = make_float4(0.3f, 0.3f, 0.3f, 0.3f)
static const float	PHASE_ISOTROPIC = M_1_4PI_F
static const float	RAYLEIGH_PHASE_SCALE = (3.0f / 16.0f) * M_1_PI_F
static const float	G = 0.8f
static const float	SQR_G = G * G
static const float	EARTH_RADIUS = 6371.0f
static const float	ATMOSPHERE_THICKNESS = 100.0f
static const float	ATMOSPHERE_RADIUS = EARTH_RADIUS + ATMOSPHERE_THICKNESS
static const int	TRANSMITTANCE_STEPS = 64
static const int	IN_SCATTERING_STEPS = 64
static const int	TRANSMITTANCE_RES_X = 256
static const int	TRANSMITTANCE_RES_Y = 64
static const float4	SUN_SPECTRAL_IRRADIANCE = make_float4(1.679f, 1.828f, 1.986f, 1.307f)
static const float4	MOLECULAR_SCATTERING_COEFFICIENT_BASE
static const float4	OZONE_ABSORPTION_CROSS_SECTION
static const float	OZONE_MEAN_DOBSON = 334.5f
static const float4	AEROSOL_ABSORPTION_CROSS_SECTION
static const float4	AEROSOL_SCATTERING_CROSS_SECTION
static const float	AEROSOL_BASE_DENSITY = 1.3681e20f
static const float	AEROSOL_BACKGROUND_DENSITY = 2e6f
static const float	AEROSOL_HEIGHT_SCALE = 0.73f
static const float3	SPECTRAL_XYZ [4]

Function Documentation

◆ aerosol_phase_function()

float aerosol_phase_function ( const float cos_theta )

inline

Definition at line 88 of file sky_multiple_scattering.cpp.

References cos_theta(), G, M_1_4PI_F, SQR_G, and sqrtf.

Referenced by SkyMultipleScattering::get_inscattering().

◆ get_aerosol_density()

float get_aerosol_density ( const float h )

inline

Definition at line 106 of file sky_multiple_scattering.cpp.

References AEROSOL_BACKGROUND_DENSITY, AEROSOL_BASE_DENSITY, AEROSOL_HEIGHT_SCALE, and expf.

Referenced by SkyMultipleScattering::get_atmosphere_collision_coefficients().

◆ get_molecular_absorption_coefficient()

float4 get_molecular_absorption_coefficient ( const float h )

inline

Definition at line 99 of file sky_multiple_scattering.cpp.

References expf, fmaxf, logf, OZONE_ABSORPTION_CROSS_SECTION, OZONE_MEAN_DOBSON, and sqr.

Referenced by SkyMultipleScattering::get_atmosphere_collision_coefficients().

◆ get_molecular_scattering_coefficient()

float4 get_molecular_scattering_coefficient ( const float h )

inline

Definition at line 94 of file sky_multiple_scattering.cpp.

References expf, MOLECULAR_SCATTERING_COEFFICIENT_BASE, and powf.

Referenced by SkyMultipleScattering::get_atmosphere_collision_coefficients().

◆ molecular_phase_function()

float molecular_phase_function ( const float cos_theta )

inline

Definition at line 83 of file sky_multiple_scattering.cpp.

References cos_theta(), RAYLEIGH_PHASE_SCALE, and sqr.

Referenced by SkyMultipleScattering::get_inscattering().

◆ SKY_earth_intersection_angle()

float SKY_earth_intersection_angle ( float altitude )

Definition at line 397 of file sky_multiple_scattering.cpp.

References asinf, EARTH_RADIUS, and M_PI_2_F.

Referenced by sky_texture_precompute_nishita().

◆ SKY_multiple_scattering_precompute_sun()

void SKY_multiple_scattering_precompute_sun	(	float	sun_elevation,
		float	angular_diameter,
		float	altitude,
		float	air_density,
		float	aerosol_density,
		float	ozone_density,
		float	r_pixel_bottom[3],
		float	r_pixel_top[3] )

Definition at line 360 of file sky_multiple_scattering.cpp.

References ATMOSPHERE_THICKNESS, clamp(), cosf, SkyMultipleScattering::get_transmittance(), M_2PI_F, M_PI_2_F, spectral_to_xyz(), SUN_SPECTRAL_IRRADIANCE, top, float3::x, float3::y, and float3::z.

Referenced by SkyTextureNode::get_sun_average_radiance(), and sky_texture_precompute_nishita().

◆ SKY_multiple_scattering_precompute_texture()

void SKY_multiple_scattering_precompute_texture	(	float *	pixels,
		int	stride,
		int	width,
		int	height,
		float	sun_elevation,
		float	altitude,
		float	air_density,
		float	aerosol_density,
		float	ozone_density )

Definition at line 302 of file sky_multiple_scattering.cpp.

References ATMOSPHERE_RADIUS, begin(), clamp(), copysignf, cosf, EARTH_RADIUS, SkyMultipleScattering::get_inscattering(), L, l, M_2PI_F, M_PI_2_F, make_float2, make_float3(), SkyMultipleScattering::precompute_lut(), ray_sphere_intersection(), sinf, SKY_parallel_for(), spectral_to_xyz(), sqr, sun_direction(), float2::x, float3::x, x, float2::y, float3::y, y, and float3::z.

Referenced by SkyLoader::load_pixels(), and blender::nodes::node_shader_tex_sky_cc::node_shader_gpu_tex_sky().

◆ spectral_to_xyz()

float3 spectral_to_xyz ( const float4 L )

inline

Definition at line 112 of file sky_multiple_scattering.cpp.

References i, L, make_float3(), and SPECTRAL_XYZ.

Referenced by SKY_multiple_scattering_precompute_sun(), and SKY_multiple_scattering_precompute_texture().

Variable Documentation

◆ AEROSOL_ABSORPTION_CROSS_SECTION

const float4 AEROSOL_ABSORPTION_CROSS_SECTION

static

Initial value:

= make_float4(

2.8722e-24f, 4.6168e-24f, 7.9706e-24f, 1.3578e-23f)

make_float4

#define make_float4

Definition at line 68 of file sky_multiple_scattering.cpp.

Referenced by SkyMultipleScattering::get_atmosphere_collision_coefficients().

◆ AEROSOL_BACKGROUND_DENSITY

const float AEROSOL_BACKGROUND_DENSITY = 2e6f

static

Definition at line 73 of file sky_multiple_scattering.cpp.

Referenced by get_aerosol_density().

◆ AEROSOL_BASE_DENSITY

const float AEROSOL_BASE_DENSITY = 1.3681e20f

static

Definition at line 72 of file sky_multiple_scattering.cpp.

Referenced by get_aerosol_density().

◆ AEROSOL_HEIGHT_SCALE

const float AEROSOL_HEIGHT_SCALE = 0.73f

static

Definition at line 74 of file sky_multiple_scattering.cpp.

Referenced by get_aerosol_density().

◆ AEROSOL_SCATTERING_CROSS_SECTION

const float4 AEROSOL_SCATTERING_CROSS_SECTION

static

Initial value:

= make_float4(

1.5908e-22f, 1.7711e-22f, 2.0942e-22f, 2.4033e-22f)

Definition at line 70 of file sky_multiple_scattering.cpp.

Referenced by SkyMultipleScattering::get_atmosphere_collision_coefficients().

◆ ATMOSPHERE_RADIUS

const float ATMOSPHERE_RADIUS = EARTH_RADIUS + ATMOSPHERE_THICKNESS

static

Definition at line 51 of file sky_multiple_scattering.cpp.

Referenced by atmosphere_intersection(), SkyMultipleScattering::get_transmittance(), and SKY_multiple_scattering_precompute_texture().

◆ ATMOSPHERE_THICKNESS

const float ATMOSPHERE_THICKNESS = 100.0f

static

Definition at line 50 of file sky_multiple_scattering.cpp.

Referenced by SkyMultipleScattering::get_inscattering(), and SKY_multiple_scattering_precompute_sun().

◆ EARTH_RADIUS

const float EARTH_RADIUS = 6371.0f

static

Definition at line 48 of file sky_multiple_scattering.cpp.

Referenced by SkyMultipleScattering::get_inscattering(), SkyMultipleScattering::get_transmittance(), SkyMultipleScattering::lookup_multiscattering(), ray_optical_depth(), single_scattering(), SKY_earth_intersection_angle(), SKY_multiple_scattering_precompute_texture(), SKY_single_scattering_precompute_texture(), sun_radiation(), and surface_intersection().

◆ G

const float G = 0.8f

static

Definition at line 45 of file sky_multiple_scattering.cpp.

◆ GROUND_ALBEDO

const float4 GROUND_ALBEDO = make_float4(0.3f, 0.3f, 0.3f, 0.3f)

static

Definition at line 41 of file sky_multiple_scattering.cpp.

Referenced by SkyMultipleScattering::lookup_multiscattering().

◆ IN_SCATTERING_STEPS

const int IN_SCATTERING_STEPS = 64

static

Definition at line 54 of file sky_multiple_scattering.cpp.

Referenced by SkyMultipleScattering::get_inscattering().

◆ MOLECULAR_SCATTERING_COEFFICIENT_BASE

const float4 MOLECULAR_SCATTERING_COEFFICIENT_BASE

static

Initial value:

= make_float4(

6.605e-3f, 1.067e-2f, 1.842e-2f, 3.156e-2f)

Definition at line 62 of file sky_multiple_scattering.cpp.

Referenced by get_molecular_scattering_coefficient().

◆ OZONE_ABSORPTION_CROSS_SECTION

const float4 OZONE_ABSORPTION_CROSS_SECTION

static

Initial value:

= make_float4(

3.472e-25f, 3.914e-25f, 1.349e-25f, 11.03e-27f)

Definition at line 64 of file sky_multiple_scattering.cpp.

Referenced by get_molecular_absorption_coefficient().

◆ OZONE_MEAN_DOBSON

const float OZONE_MEAN_DOBSON = 334.5f

static

Definition at line 67 of file sky_multiple_scattering.cpp.

Referenced by get_molecular_absorption_coefficient().

◆ PHASE_ISOTROPIC

const float PHASE_ISOTROPIC = M_1_4PI_F

static

Definition at line 42 of file sky_multiple_scattering.cpp.

Referenced by SkyMultipleScattering::lookup_multiscattering().

◆ RAYLEIGH_PHASE_SCALE

const float RAYLEIGH_PHASE_SCALE = (3.0f / 16.0f) * M_1_PI_F

static

Definition at line 43 of file sky_multiple_scattering.cpp.

Referenced by molecular_phase_function().

◆ SPECTRAL_XYZ

const float3 SPECTRAL_XYZ[4]

static

Initial value:

                                 = {
    make_float3(53.386917738564668023f, 22.981337506691024754f, 0.0f),
    make_float3(43.904844466369358263f, 71.347795700053393866f, 0.102506867965741307f),
    make_float3(1.6137278251608962005f, 18.422960591455485011f, 31.742921188390805758f),
    make_float3(20.762668673810577145f, 2.3614213523314368527f, 110.48009643252140334f),
}