Materials and Constants

In 3D graphics, a material describes how a surface looks — its texture, color, and shine. The scene3d library comes with a built-in material collection: bricks, marble, grass, planets, and more.

But before you start using them, you’ll learn a powerful coding habit: constants — named values that make your code easier to read, update, and reuse.

The Problem with Repeated Values

Run the code below. It creates two shapes using the same slate-grey color '#708090'.

Now look closely — that hex code appears twice. What if you wanted to repaint both shapes red? You’d need to find and change every occurrence. In a longer program, it’s easy to miss one and end up with a broken-looking scene.

import scene3d

scene = scene3d.Scene()
scene.set_sky('#1a1a2e')
scene.set_ground(length=10, width=10)

sphere = scene3d.Shapes.Sphere(diameter=1, segments=16)
sphere.set_color('#708090')
sphere.set_position(-2, 0.5, 0)
scene.add(sphere)

box = scene3d.Shapes.Box(width=1, height=1, depth=1)
box.set_color('#708090')
box.set_position(2, 0.5, 0)
scene.add(box)

Constants to the Rescue

A constant is a name you give to a value so you only have to write the value once. By convention, constant names are written in ALL_CAPS — this signals to any programmer reading the code:

“This is a fixed setting. Define it once at the top, then use the name everywhere.”

STONE = '#708090'

Now instead of writing '#708090' twice, you write STONE twice. To repaint both shapes, you change one line at the top — and everything updates.

Name	What it signals
`STONE`	A constant — a fixed, named value
`sphere`	A regular variable
`set_color`	A function call
`'#708090'`	A magic value — no name, easy to mistype or miss

Try it: change STONE = '#708090' to STONE = '#e94560' on the first line of the code below and run again — both shapes change at once.

import scene3d

STONE = '#708090'

scene = scene3d.Scene()
scene.set_sky('#1a1a2e')
scene.set_ground(length=10, width=10)

sphere = scene3d.Shapes.Sphere(diameter=1, segments=16)
sphere.set_color(STONE)
sphere.set_position(-2, 0.5, 0)
scene.add(sphere)

box = scene3d.Shapes.Box(width=1, height=1, depth=1)
box.set_color(STONE)
box.set_position(2, 0.5, 0)
scene.add(box)

{ “question_type”: “multiple_choice”, “question”: “Which variable name follows the Python convention for a constant?”, “options”: [ { “key”: “a”, “text”: “nightSky” }, { “key”: “b”, “text”: “Night_Sky” }, { “key”: “c”, “text”: “nightsky” }, { “key”: “d”, “text”: “NIGHT_SKY” } ], “answer”: “d”, “submitted_answer”: “” }

{ “question_type”: “true_false”, “question”: “Python automatically prevents you from changing the value of a constant.”, “answer”: “False”, “submitted_answer”: “” }

Sky Constants — The Library Already Named Them

You’ve set the sky with hex colors like '#87ceeb'. But scene3d also includes pre-built sky environments, each with its own constant name:

Constant	What it looks like
`scene3d.Sky.CLOUDS`	Fluffy white clouds
`scene3d.Sky.DEEP_SPACE`	Dark sky filled with stars
`scene3d.Sky.PURE_SKY`	Clear blue sky
`scene3d.Sky.MODERN_BUILDINGS`	City skyline reflections
`scene3d.Sky.ORLANDO_STADIUM`	Stadium lighting

These are constants the library defined for you — you use them exactly the same way as any constant you’d write yourself.

Try swapping Sky.CLOUDS for another option in the code below.

import scene3d

scene = scene3d.Scene()
scene.set_sky(scene3d.Sky.CLOUDS)
scene.set_ground(length=10, width=10)

sphere = scene3d.Shapes.Sphere(diameter=1.5, segments=24)
sphere.set_color('#e94560')
sphere.set_position(0, 0.75, 0)
scene.add(sphere)

Giving the Ground a Material

set_ground returns a mesh — the same kind of object as a sphere or box. That means you can call set_material on it to apply a texture:

ground = scene.set_ground(length=20, width=20)
ground.set_material(scene3d.Material.Grass.Bright)
ground.set_tiling(8)

set_tiling(8) repeats the texture 8 times across the surface. Without tiling, a single tile would stretch to cover the entire ground and look blurry.

import scene3d

scene = scene3d.Scene()
scene.set_sky(scene3d.Sky.PURE_SKY)

ground = scene.set_ground(length=20, width=20)
ground.set_material(scene3d.Material.Grass.Bright)
ground.set_tiling(8)

sphere = scene3d.Shapes.Sphere(diameter=1.5, segments=24)
sphere.set_color('#e94560')
sphere.set_position(0, 0.75, 0)
scene.add(sphere)

Materials on Shapes

set_material works on any shape — sphere, box, or cylinder. The materials are organized into groups. Here are some to explore:

Group	Constants	Works great on…
`Material.Bricks`	`.DarkClay`, `.RoughStone`	Boxes
`Material.Marble`	`.Gray`, `.Brown`, `.Black`	Spheres, cylinders
`Material.Planets`	`.Earth`, `.Mars`, `.Jupiter`	Spheres
`Material.Wood`	`.Oak`	Cylinders, boxes
`Material.Snow`	`.Fresh`	Any surface
`Material.Fabric`	`.Denim`, `.BurgundyRibbed`	Any surface

You can also control shine with set_glossiness: - 0.0 = completely matte - 1.0 = mirror-like

set_glossiness only works on shapes that use set_material — it has no effect on plain set_color shapes.

import scene3d

scene = scene3d.Scene()
scene.set_sky(scene3d.Sky.PURE_SKY)
ground = scene.set_ground(length=20, width=20)
ground.set_material(scene3d.Material.Grass.Bright)
ground.set_tiling(8)

box = scene3d.Shapes.Box(width=2, height=2, depth=2)
box.set_material(scene3d.Material.Bricks.DarkClay)
box.set_position(-3, 1, 0)
scene.add(box)

sphere = scene3d.Shapes.Sphere(diameter=2, segments=24)
sphere.set_material(scene3d.Material.Marble.Gray)
sphere.set_glossiness(0.8)
sphere.set_position(3, 1, 0)
scene.add(sphere)

{ “question_type”: “multiple_choice”, “question”: “What does set_material() do?”, “options”: [ { “key”: “a”, “text”: “Changes the shape of an object” }, { “key”: “b”, “text”: “Applies a pre-built texture and lighting material to a surface” }, { “key”: “c”, “text”: “Moves an object to a new position” }, { “key”: “d”, “text”: “Sets the background sky color” } ], “answer”: “b”, “submitted_answer”: “” }

{ “question_type”: “true_false”, “question”: “set_glossiness(0.9) works on a sphere that has only had set_color applied.”, “answer”: “False”, “submitted_answer”: “” }

Your Material Library

When you gather all the material choices into named constants at the top of your code, they form a material library — a single place where the look of the entire scene is defined.

Try swapping any of the three constants below: - SKY — try Sky.CLOUDS, Sky.MODERN_BUILDINGS, Sky.ORLANDO_STADIUM - GROUND — try Material.Snow.Fresh, Material.Gravel.LightGray - PLANET — try Material.Planets.Mars, Material.Planets.Jupiter, Material.Planets.Venus

import scene3d

SKY    = scene3d.Sky.DEEP_SPACE
GROUND = scene3d.Material.Gravel.LightGray
PLANET = scene3d.Material.Planets.Earth

scene = scene3d.Scene()
scene.set_sky(SKY)

ground = scene.set_ground(length=20, width=20)
ground.set_material(GROUND)
ground.set_tiling(8)

planet = scene3d.Shapes.Sphere(diameter=3, segments=32)
planet.set_material(PLANET)
planet.set_position(0, 1.5, 0)
scene.add(planet)

{ “question_type”: “multiple_choice”, “question”: “What is the main advantage of using STONE = ‘#708090’ instead of writing ‘#708090’ each time?”, “options”: [ { “key”: “a”, “text”: “It makes Python run faster” }, { “key”: “b”, “text”: “It prevents the color from ever being changed” }, { “key”: “c”, “text”: “Updating all uses only requires editing one line” }, { “key”: “d”, “text”: “It makes the hex code valid” } ], “answer”: “c”, “submitted_answer”: “” }

{ “question_type”: “multiple_choice”, “question”: “Which is the correct way to define a constant for the Bricks.DarkClay material?”, “options”: [ { “key”: “a”, “text”: “wall = scene3d.Material.Bricks.DarkClay” }, { “key”: “b”, “text”: “Wall = scene3d.Material.Bricks.DarkClay” }, { “key”: “c”, “text”: “WALL = scene3d.Material.Bricks.DarkClay” }, { “key”: “d”, “text”: “wall_Material = scene3d.Material.Bricks.DarkClay” } ], “answer”: “c”, “submitted_answer”: “” }

Think of a scene you’d like to build — a beach, a space station, a snowy forest, or anything you like.

Write out a mini material library for it: at least three constants with ALL_CAPS names, each set to a scene3d.Sky or scene3d.Material value. For example:

SKY = scene3d.Sky.DEEP_SPACE
GROUND = scene3d.Material.Snow.Fresh

Describe what the finished scene would look like.