Materials

Materials define how surfaces interact with light, controlling color, shininess, and reflectivity.

Material Properties

struct Material {
    Vec3 color;              // Base RGB color
    float ambient;           // Ambient light factor (0.1)
    float diffuse;           // Diffuse factor (0.7)
    float specularIntensity; // Specular brightness
    float shininess;         // Specular tightness
    float reflectivity;      // Mirror reflection
    float transparency;      // Transparency (0-1)
    float refractiveIndex;   // Index of refraction (1.0-3.0)
};

Color

The base color of the surface, defined as RGB values in [0, 1]:

Vec3 red(0.9f, 0.2f, 0.15f);
Vec3 blue(0.2f, 0.4f, 0.9f);
Vec3 gold(1.0f, 0.84f, 0.0f);

Available Colors

Color	RGB
Red	(0.9, 0.2, 0.15)
Blue	(0.2, 0.4, 0.9)
Green	(0.2, 0.85, 0.3)
Gold	(1.0, 0.84, 0.0)
Purple	(0.6, 0.2, 0.9)
White	(0.95, 0.95, 0.95)

Ambient

Simulates indirect lighting. Even in shadow, surfaces have some visibility:

Vec3 ambient = material.color * material.ambient;
// Typically 0.1 (10%)

Diffuse

Lambertian reflection for matte surfaces. Light scatters equally:

float lambert = max(0, normal.dot(lightDir));
Vec3 diffuse = material.color * lambert * material.diffuse;

The diffuse factor (typically 0.7) controls contribution.

Specular

Intensity

How bright the specular highlight is:

• 0.0 - No highlight (pure matte)
• 0.5 - Moderate
• 1.0 - Maximum brightness

Shininess

How tight/focused the highlight is:

Shininess	Look
8	Very soft, spread
32	Plastic-like
128	Metallic
256	Near-mirror

// Blinn-Phong
Vec3 halfDir = normalize(lightDir + viewDir);
float spec = pow(max(0, normal.dot(halfDir)), shininess);
Vec3 specular = light.color * spec * material.specularIntensity;

Reflectivity

How much the surface acts as a mirror:

if (reflectivity > 0.001f) {
    Vec3 reflectDir = ray.direction.reflect(normal);
    Vec3 reflectedColor = traceRay(reflectRay, depth + 1);
    
    // Blend based on Fresnel
    finalColor = localColor * (1 - fresnel) + reflectedColor * fresnel;
}

Material Presets

The UI provides quick presets:

Matte

{ specular: 0.1, shininess: 8, reflectivity: 0.0 }

Flat, non-shiny surface. Think chalk or unfinished wood.

Plastic

{ specular: 0.4, shininess: 32, reflectivity: 0.1 }

Slightly shiny with small specular highlight. Subtle reflection.

Glossy

{ specular: 0.6, shininess: 64, reflectivity: 0.3 }

Clear specular, noticeable reflection. Like polished plastic.

Metal

{ specular: 0.9, shininess: 128, reflectivity: 0.7 }

Bright, tight specular. Strong reflections. Metallic appearance.

Chrome

{ specular: 1.0, shininess: 256, reflectivity: 0.95 }

Near-perfect reflection. Chrome or polished silver.

Glass

{ specular: 1.0, shininess: 256, transparency: 0.95, refractiveIndex: 1.5 }

Clear transparent material with light bending.

Diamond

{ specular: 1.0, shininess: 512, transparency: 0.95, refractiveIndex: 2.4 }

High dispersion crystal with strong light bending.

Water

{ specular: 0.8, shininess: 128, transparency: 0.9, refractiveIndex: 1.33 }

Liquid-like appearance with subtle blue tint.

Visual Comparison

Matte         Plastic       Glossy        Metal         Mirror
  ○             ○             ⊙             ◉             ◯
no shine    soft shine    clear spot   bright spot   pure reflect

Combining Properties

Materials are a combination of all properties:

Material gold;
gold.color = Vec3(1.0f, 0.84f, 0.0f);  // Gold color
gold.specularIntensity = 0.9f;          // Bright highlight
gold.shininess = 128.0f;                // Tight highlight
gold.reflectivity = 0.8f;               // Very reflective

Ground Plane Material

The ground has its own material:

groundPlane.material.color = Vec3(0.15f, 0.15f, 0.17f);  // Dark gray
groundPlane.material.specularIntensity = 0.1f;           // Subtle
groundPlane.material.reflectivity = 0.15f;               // Slight reflection

Adjust ground reflectivity in the View tab.