Table of Contents

Struct LightingModel

Namespace
Egami.Operations
Assembly
Egami.dll

How a surface reflects light in Lighting(Light, LightingModel, LightingOptions?): Diffuse(float) (SVG's feDiffuseLighting, Lambert's N·L) or Specular(float, float) (feSpecularLighting, Phong–Blinn's (N·H)^shininess), with SVG's and Skia's constants.

public readonly record struct LightingModel : IEquatable<LightingModel>
Implements
Inherited Members

Examples

// Three light sources, as SVG and Skia have them. Positions are pixels: x right, y down, z up out of the image.
Light sun = new DistantLight(azimuth: 225, elevation: 40);              // from the top left, 40° up
Light bulb = new PointLight(new Vector3(60, 20, 80)) { Color = new Rgba8(255, 240, 210, 255) };
Light spot = new SpotLight(new Vector3(0, 0, 150), target: new Vector3(120, 60, 0), exponent: 4, coneAngle: 30);

// Two ways a surface reflects: matte (N·L) or shiny (a highlight, (N·H)^shininess).
LightingModel matte = LightingModel.Diffuse(kd: 1.2f);
LightingModel shiny = LightingModel.Specular(ks: 1, shininess: 20);

using Raster<Rgba8> map = logo.Derive(ops => ops.Lighting(sun, matte), Ct);   // the light map, opaque
using Raster<Rgba8> glints = logo.Derive(ops => ops.Lighting(bulb, shiny), Ct); // alpha = brightest channel
using Raster<Rgba8> pool = logo.Derive(ops => ops.Lighting(spot, matte), Ct);

Properties

Constant

Gets the reflectance: SVG's diffuseConstant (kd) or specularConstant (ks).

public float Constant { get; }

Property Value

float

IsSpecular

Gets a value indicating whether the model is specular; otherwise it is diffuse.

public bool IsSpecular { get; }

Property Value

bool

Shininess

Gets the specular exponent (SVG's specularExponent, Skia's shininess); 0 for a diffuse model.

public float Shininess { get; }

Property Value

float

Methods

Diffuse(float)

A matte surface: each pixel is the light's color times kd times N·L, the cosine between the surface normal and the direction to the light, clamped to 0..1. The light map is opaque.

public static LightingModel Diffuse(float kd = 1)

Parameters

kd float

The reflectance, SVG's diffuseConstant and Skia's kd; 0 or more.

Returns

LightingModel

The model.

Exceptions

ArgumentOutOfRangeException

kd is negative or not finite.

Specular(float, float)

A shiny surface: each pixel is the light's color times ks times (N·H)^shininess, where H is halfway between the direction to the light and the viewer straight above, clamped to 0..1. The light map's alpha is the largest of its color channels, so it is transparent where there is no highlight.

public static LightingModel Specular(float ks = 1, float shininess = 1)

Parameters

ks float

The reflectance, SVG's specularConstant and Skia's ks; 0 or more.

shininess float

The exponent, SVG's specularExponent and Skia's shininess, from 1 to 128; larger is a smaller, sharper highlight.

Returns

LightingModel

The model.

Exceptions

ArgumentOutOfRangeException

ks is negative or not finite, or shininess is not from 1 to 128.

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