Flex Engine is a personal game engine I began work on in early 2017. I use it as a playground for learning about real-time rendering and simulation techniques. Flex Engine is not a commercial game engine nor is it intended for public use.

Building Flex

See build.md

Notable Features

• Vulkan rendering backend (VulkanRenderer.cpp)
• In-game scripting language compiler/editor & virtual machine (VirtualMachine.cpp)
• Conditional checksum-based shader recompilation (ShaderCompiler.cpp)
• File modification monitoring for textures, meshes, prefabs, shaders, config files, etc. (ResourceManager.cpp)
• Scene editor with serialization (BaseScene.cpp)
• Editor tools (transform gizmo, property editor, keybinding editor, etc.) (Editor.cpp)
• Basic profiling capture/inspection tools
• Support for Windows & linux
• Rendering:
  • Marching cubes terrain generator & renderer
  • Gerstner wave ocean renderer
  • Rectangular area lights (direct-only diffuse & specular)
  • Physically-based shading model
  • Image-based lighting
  • Screen-space ambient occlusion
  • Stable cascaded shadow mapping
  • Temporal anti-aliasing
  • Signed distance field (SDF) font generation & rendering
  • GPU-based particle simulation

Procedural terrain generated on the GPU

Gerstner wave ocean simulation

Cascaded Shadow Mapping

Two million particles simulated and rendered entirely on the GPU

Profiler overlay showing a breakdown the CPU-time of a single frame

Some editor windows

Screen-Space Ambient Occlusion (SSAO)

GBuffer (top-left to bottom-right): position, albedo, normal, final image, depth, metallic, AO, roughness

View into editor

See more screenshots here

Dependencies

Flex Engine uses the following open-source libraries:

• Bullet - Collision detection & rigid body simulation
• FreeType - Font loading
• glfw - Window creation, input handling
• glm - Math operations
• ImGui - User interface
• OpenAL - Audio loading and playback
• stb - Image loading
• cgltf - Mesh loading
• volk - Vulkan meta-loader

License

Flex engine is licensed under the MIT license. See LICENSE.md for details.

Acknowledgements

A huge thank you must be given to the following individuals and organizations for their incredibly useful resources:

• Baldur Karlsson of github.com/baldurk/renderdoc
• Alexander Overvoorde of vulkan-tutorial.com
• Sascha Willems of github.com/SaschaWillems/Vulkan
• Joey de Vries of learnopengl.com
• Andrew Maximov for the pistol model and textures artisaverb.info/PBT.html
• FreePBR.com for the high-quality PBR textures
• All authors and contributors to the open-source libraries mentioned above

Blog

Stay (somewhat) up to date about this project on my blog at ajweeks.com/blog