sh.hpp File Reference

Common spherical harmonics functions. More...

#include "math/ibl.hpp"
#include "math/matrix.hpp"

Macros
#define	M_SQRT_PI   1.77245385090551602729816748334114518
#define	M_SQRT3   1.73205080756887729352744634150587237
#define	M_SQRT5   2.23606797749978969640917366873127624
#define	M_SQRT15   3.87298334620741688517926539978239961

Variables
constexpr math::int32	sh2Count = 4
constexpr math::int32	sh3Count = 9
constexpr math::int32	sh4Count = 16
constexpr float	ki3 [sh3Count]
	Precomputed Lambertian reflection coefficients for the 3 band spherical harmonics.

Detailed Description

Common spherical harmonics functions.

Spherical harmonics (SH) are used to represent functions on the surface of a sphere, particularly for lighting and shading. SH allows for efficient approximations of complex lighting environments, such as image-based lighting (IBL), by encoding diffuse light and low-frequency details. SH are commonly used in precomputed radiance transfer (PRT) to achieve realistic lighting with low computational cost, especially for dynamic and global illumination in 3D scenes, enabling real-time performance in games.

Based on this project: https://google.github.io/filament/Filament.html

Variable Documentation

sh2Count

math::int32 sh2Count = 4

constexpr

L1 spherical harmonics coefficient count. (2 * 2)

sh3Count

math::int32 sh3Count = 9

constexpr

L2 spherical harmonics coefficient count. (3 * 3)

sh4Count

math::int32 sh4Count = 16

constexpr

L3 spherical harmonics coefficient count. (4 * 4)

ki3

float ki3[sh3Count]

constexpr

Initial value:

                    =
{
    (float)0.886226925452757940959713778283912688,
    (float)1.023326707946488278722085851768497380,
    (float)1.023326707946488278722085851768497380,
    (float)1.023326707946488278722085851768497380,
    (float)0.143014255134963907956091588857816532,
    (float)0.286028510269927815912183177715633065,
    (float)0.495415912200751318295033343019895256,
    (float)0.286028510269927815912183177715633065,
    (float)0.143014255134963907956091588857816532
}

Precomputed Lambertian reflection coefficients for the 3 band spherical harmonics.