Materials Showcase

This example demonstrates the different material types available in Hikari, arranged in a scene to clearly show their properties.

Available Materials

Hikari supports several physically-based materials:

• MatteMaterial: Diffuse surfaces with optional roughness (Oren-Nayar model)

• MirrorMaterial: Perfect specular reflection

• GlassMaterial: Transparent material with refraction and optional roughness

• PlasticMaterial: Combination of diffuse and glossy specular reflection (coated diffuse)

• ConductorMaterial: Physically-based metals with complex IOR (eta + k)

using GeometryBasics
using Hikari
using FileIO
using ImageShow

# Helper to tessellate primitives
to_mesh(prim) = normal_mesh(prim isa Sphere ? Tesselation(prim, 64) : prim)

# Helper to create a sphere resting on the ground
LowSphere(radius, x, z) = Sphere(Point3f(x, radius, z), radius)

# ============================================
# Define all material types
# ============================================

# 1. MATTE MATERIALS - Diffuse reflection
# Smooth diffuse (Lambertian) - terracotta color
matte_smooth = Hikari.MatteMaterial(Kd=Hikari.RGBSpectrum(0.8f0, 0.4f0, 0.3f0))
# Rough diffuse (Oren-Nayar) - chalk/clay appearance
matte_rough = Hikari.MatteMaterial(Kd=Hikari.RGBSpectrum(0.85f0, 0.85f0, 0.8f0), σ=60f0)

# 2. MIRROR - Perfect specular reflection
# Silver mirror
mirror_silver = Hikari.MirrorMaterial(Kr=Hikari.RGBSpectrum(0.95f0, 0.93f0, 0.88f0))

# 3. CONDUCTOR MATERIALS - Physically-based metals
# Gold
gold = Hikari.ConductorMaterial(
    eta=Hikari.RGBSpectrum(0.15557f0, 0.42415f0, 1.3831f0),
    k=Hikari.RGBSpectrum(3.6024f0, 2.4721f0, 1.9155f0),
    roughness=0.05f0,
)
# Copper
copper = Hikari.ConductorMaterial(
    eta=Hikari.RGBSpectrum(0.27105f0, 0.67693f0, 1.3164f0),
    k=Hikari.RGBSpectrum(3.6092f0, 2.6248f0, 2.2921f0),
    roughness=0.1f0,
)

# 4. GLASS MATERIALS - Refraction and transparency
# Clear glass
glass_clear = Hikari.GlassMaterial(index=1.5f0)
# Frosted glass
glass_frosted = Hikari.GlassMaterial(roughness=0.15f0, index=1.5f0)

# 5. PLASTIC MATERIALS - Diffuse + glossy specular
# Shiny red plastic
plastic_shiny = Hikari.PlasticMaterial(
    Kd=Hikari.RGBSpectrum(0.8f0, 0.1f0, 0.1f0),
    Ks=Hikari.RGBSpectrum(0.4f0),
    roughness=0.02f0,
)
# Matte blue plastic
plastic_matte = Hikari.PlasticMaterial(
    Kd=Hikari.RGBSpectrum(0.15f0, 0.3f0, 0.7f0),
    Ks=Hikari.RGBSpectrum(0.15f0),
    roughness=0.25f0,
)

# Floor
floor_mat = Hikari.MatteMaterial(Kd=Hikari.RGBSpectrum(0.85f0))

# ============================================
# Create scene with 3x3 grid of spheres
# ============================================
# Back row:   Matte Smooth | Matte Rough  | Glass Clear
# Middle row: Mirror Silver| Gold         | Copper
# Front row:  Frosted Glass| Plastic Shiny| Plastic Matte

r = 0.38f0
sx, sz = 1.0f0, 1.1f0

scene = Hikari.Scene()

# Back row (z = sz)
push!(scene, to_mesh(LowSphere(r, -sx, sz)), matte_smooth)
push!(scene, to_mesh(LowSphere(r, 0f0, sz)), matte_rough)
push!(scene, to_mesh(LowSphere(r, sx, sz)), glass_clear)

# Middle row (z = 0)
push!(scene, to_mesh(LowSphere(r, -sx, 0f0)), mirror_silver)
push!(scene, to_mesh(LowSphere(r, 0f0, 0f0)), gold)
push!(scene, to_mesh(LowSphere(r, sx, 0f0)), copper)

# Front row (z = -sz)
push!(scene, to_mesh(LowSphere(r, -sx, -sz)), glass_frosted)
push!(scene, to_mesh(LowSphere(r, 0f0, -sz)), plastic_shiny)
push!(scene, to_mesh(LowSphere(r, sx, -sz)), plastic_matte)

# Ground plane
push!(scene, to_mesh(Rect3f(Vec3f(-3, 0, -3), Vec3f(6, 0.01, 6))), floor_mat)

# Lighting
push!(scene, Hikari.PointLight(Point3f(3f0, 4f0, -3f0), Hikari.RGBSpectrum(15f0)))
push!(scene, Hikari.PointLight(Point3f(-3f0, 3f0, -2f0), Hikari.RGBSpectrum(6f0)))
push!(scene, Hikari.PointLight(Point3f(0f0, 3f0, 3f0), Hikari.RGBSpectrum(8f0)))
push!(scene, Hikari.AmbientLight(Hikari.RGBSpectrum(0.05f0)))

Hikari.sync!(scene)

# Camera setup
resolution = Point2f(1024)
film = Hikari.Film(resolution)
camera = Hikari.PerspectiveCamera(
    Point3f(0f0, 3.5f0, -5f0), Point3f(0f0, 0.2f0, 0f0), film; fov=40f0,
)
Hikari.clear!(film)

# Render
integrator = Hikari.VolPath(samples=16, max_depth=5)
integrator(scene, film, camera)

img = Hikari.postprocess!(film; exposure=1.0f0, tonemap=:aces, gamma=2.2f0)
Array(img)

Material Properties Reference

Material	Key Parameters	Best For
MatteMaterial	Kd (color), σ (roughness 0-90°)	Diffuse surfaces: walls, cloth, paper, chalk
MirrorMaterial	Kr (reflectance color)	Perfect specular mirrors
GlassMaterial	Kr, Kt, roughness, index (IOR)	Glass, water, gems, ice, frosted surfaces
PlasticMaterial	Kd, Ks, roughness	Plastic, painted surfaces, ceramics
ConductorMaterial	eta, k, roughness	Physically-based metals: gold, copper, silver

Index of Refraction (IOR) Reference

Common IOR values for GlassMaterial:

• Air: 1.0

• Water: 1.33

• Glass: 1.5

• Crystal: 1.6-2.0

• Diamond: 2.42