Ranked in these QuestionsQuestion Ranking
Pro Operator overloading
Pro Geometric Tests
An almost-unique feature: can test geometry if contains(), isInside() or intersects() one other object. Offers even hit-testing methods!
Pro Behaviours handled by objects
These features make it easier to create objects that can act autonomously with complex behaviors. This makes Paper a good choice for particle effects and game development.
Pro Object constructors
Elements all have the option of being created with a hash of properties which promotes clean, concise, and contextually local coding practice.
Pro Good for making games
Paper uses a frame based approach to rendering the canvas. This makes it conceptually easier to create objects with animations and behaviors that interact and perform with other objects.
Along with Paper's approach to creating and managing objects this makes Paper especially good for creating applications with complex behaviors with many elements doing different actions at once, and makes it a good choice for making games.
Pro Feature rich
Effects: Anaglyph, cross-eyed and parallax barrier.
Scenes: add and remove objects at run-time; fog
Cameras: perspective and orthographic; controllers: trackball, FPS, path and more
Animation: armatures, forward kinematics, inverse kinematics, morph and keyframe
Lights: ambient, direction, point and spot lights; shadows: cast and receive
Materials: Lambert, Phong, Standard, smooth shading, textures, PBR and more
Shaders: access to full OpenGL Shading Language (GLSL) capabilities: lens flare, depth pass and extensive post-processing library
Objects: meshes, particles, sprites, lines, ribbons, bones and more - all with Level of detail
Geometry: plane, cube, sphere, torus, 3D text and more; modifiers: lathe, extrude and tube
Data loaders: binary, image, JSON and scene
Utilities: full set of time and 3D math functions including frustum, matrix, quaternion, UVs and more
Export and import: utilities to create Three.js-compatible JSON files from within: Blender, openCTM, FBX, Max, and OBJ
Support: API documentation, public forum
Examples: Over 150 files of coding examples plus fonts, models, textures, sounds and other support files
Pro Helpful and friendly community
Thanks to the recently introduced forum, it is easy to find a community of helpful developers.
Pro Support for physically based rendering
With the introduction of the new MeshStandardMaterial, three.js support physically based rendering (PBR) out of the box allowing for real life quality material and lighting.
Pro Support for most industry standard file formats
Three.js has importers for most of the industry standard files format (obj, mtl, fbx, 3ds, gltf, collada, babylon, playcanvas, stl, vrml, draco and many more), making it easy to author assets in your favourite modelling software and import them for use them in three.js.
Pro Actively developed
Three.js has great project health, with activity on Github daily for bug fixes and new features.
Pro Fallback canvas rendering
Three.js offers a canvas renderer as a fallback when WebGL is not available.
Pro Support for special effects and postprocessing
Three.js support many special effects and post-processing filters including particles, lensflare, sprites, real time reflection and refraction and even area based lighting.
Pro Hundreds of officially maintained plugins, extensions, control systems, importers, exporters and special effects
The core of the three.js system is kept to a minimum to reduce file size, however there are also hundreds of extensions maintained in the offical repo on github, along with many free textures, fonts and models. You can find them all here.
Pro Plenty of tutorials and examples
Three.js official documentation provides plenty of well-written examples with a wide variety of tutorials written by the community available that you can find by doing a google search.
Con Limited to single instance
The code is written in a way that everything is global and limited to a single instance, there is no clean way to use 2 separate instances in the same page
Con Not supported in older browsers
Paper.js runs on top of HTML5 Canvas, which is not supported in older browsers.
Con Lack of versioning system means that the API changes frequently
Three.js releases a new revision about once a month, and the API can change at any time. This means that a lot of third party help found online is out of date.
Con Weak visual tools
Three.js has its own editor but it has been weakly developed. It does not support a lot of engine features.