This is a major release with significant changes. Please review the
changes when upgrading. The list below is by no means exhaustive, but
should contain the most important changes.

General

• Experimental ability to build for Android
• New input framework to natively support gamepads, joysticks, etc.
• Multi-threaded render pipeline is a lot more stable now
• New setuptools-based deployment pipeline
• Improvements to mouselook smoothness
• Cache is now at $XDG_CACHE_HOME/panda3d (~/.cache/panda3d), not ~/.panda3d
• Addition of unit test suite
• Many improvements to thread safety
• Many performance improvements
• Tons of bugfixes
• Big style cleanup of C++ source code

Python API

• Complete support for Python 3
• Support for coroutines and async/await
• Property interfaces have been added for many settings
• More flexible handling for keyboard arguments in C++ APIs
• Python bindings are completely separated out of the C++ libraries.
• Interrogate binding generator has many improvements.
• Use of pandac.PandaModules is discouraged, use panda3d.core et al
• Use of libRocket is discouraged due to lack of Python 3 support
• Tasks are now sorted in addition order when lacking a sort value
• Fixes iris/fade transitions for extreme aspect ratios
• WeakNodePath is now exposed to Python
• WindowProperties.size(x, y) deprecated; use WindowProperties(size=(x, y))
• Calling bare run() is deprecated, use base.run() instead
• downcastTo*() methods have been removed, they were already no-ops

Rendering

• Add new shader-based terrain rendering method (ShaderTerrainMesh)
• The default ColorAttrib mode is now T_vertex
• The ColorAttrib T_off mode now properly disables vertex colors entirely
• Make handling of color attributes more consistent between renderers
• Ability to create an OpenGL core profile context; set “gl-version 3 2”
• Experimental support for reverse-Z rendering for best depth precision
• sRGB framebuffers supported more widely
• Support for infinite near/far clip in lens
• Add some PBR material parameters to material class
• Addition of more built-in GLSL shader inputs; see manual.
• Add p3d_FragData[] GLSL output for MRT in GLSL 1.30
• Add flag enabling vertex shader control over point size
• Support signed ints and double-precision floats in vertex data with GLSL
• Support unsigned 11/10/10-bit floating-point textures and vertex data
• Support for SSBOs via ShaderBuffer class
• Support OpenGL FBO buffers without any attachments
• Support passing uint variables to GLSL shader
• Allow rendering objects with empty vertex data (for vertex pulling)
• Add LogicOpAttrib, for supporting logical operator blending
• Improvements to OpenGL ES support
• Support for geometry with adjacency information
• Change default alpha blending to improve blending rendered result
• New method for obtaining native OpenGL texture object
• Support windowless offscreen rendering on macOS
• Panda resets OpenGL state better before and after draw callbacks
• OpenGL renderer better supports debugging tools like apitrace
• Support fixed-depth billboards, useful for 2D tags that don’t change size

Shader generator

• Significant performance improvements
• Support for point light shadows
• Hardware skinning support
• Changes to match fixed-function pipeline better
• Fixes for normal vector normalization
• Support multiple normal maps (uses Reoriented Normal Mapping)
• Tracks modifications to materials and texture stages automatically

Lighting

• Allow specifying light color based on color temperature
• Setting specular color of a light separately is deprecated
• New GLSL inputs to make implementing lighting in shaders much easier
• Add representation for sphere light and rectangle light
• Efficiency improvements for passing light information to shader
• Interocular distance for shadow cameras now always defaults to 0
• Add low-level lighting module from RenderPipeline

Textures

• Support cube map arrays
• Support buffer textures
• Many more texture formats supported
• BC4 and BC5 compression modes supported
• Proper depth textures supported in DirectX 9 renderer
• set_ram_image(_as) directly supports buffer protocol
• TexturePeeker supports more formats and component types

Text

• Dramatic improvements to text rendering performance
• Support for HarfBuzz for higher-quality text shaping and kerning
• Support for right-to-left text
• Support for signed-distance-field rendering in egg-mkfont

Audio/video

• The default unit for audio is now 1 meter for each Panda unit.
• Native .flac loader
• Support videos with alpha channel in ffmpeg
• OpenAL stability improvements, especially on macOS
• Support loading .opus files with libopusfile
• Fix various memory leaks

Physics / collisions

• CollisionTube is renamed to CollisionCapsule.
• Box-box collision test is improved to work well with the Pusher
• More box tests for collision system: box-into-plane, box-into-poly
• Capsule (tube) can be used as “from” shape into plane, sphere, capsule, box
• Bullet objects are serializable to .bam files.
• Bullet bindings are now thread safe.
• Bullet debug drawer is more efficient; no longer inherits GeomNode.
• Various fixes to bullet vehicle wheel synchronization
• PhysX bindings are deprecated.

Pipeline / loading

• Support for Assimp library to load a broad variety of model formats
• Ability to specify min-lod, max-lod, lod-bias in .egg file
• Egg file materials support PBR-style material parameterization
• Support loading more DDS files, including DX10-style ones
• Add support for OpenEXR and HDR textures
• Support line/point thickness in bam2egg
• bam2egg no longer inserts a vestigial ModelNode at the top
• bam2egg supports depth test, offset, cull bin attributes
• Accept a .gz file wherever a .pz file is accepted
• egg-palettize supports mirror and border-color wrap modes
• More robust checks against memory corruptions when loading bad .bam files
• Support for Maya 2017 and 2018
• Support preprocessing GLSL shaders created with Shader.make

Build

• We now require using MSVC 2015 or 2017 to compile on Windows.
• At least GCC 4.8 is now required.
• With GCC/clang, enabling C++11 is now required.
• Allow building with more recent ffmpeg versions
• Support for old FFMpeg versions (before 1.1) dropped.
• The ppremake build system has been removed.
• Support for OpenSSL versions before 0.9.7 has been dropped.

C++

• Use of NULL is replaced with nullptr
• WeakPointerTo now requires use of lock() method for thread safety
• Mutex et al now satisfy C++11 Lockable constraints
• Panda headers no longer contain `using namespace std;`
• PN_int32 et al have been removed, use stdint.h types instead
• The need to link with pystub and add Python include dirs is removed.