the destroyable realtime 3d game engine
Imprimis is a fork of Tesseract, which is a fork of the Cube 2: Sauerbraten engine. The goal of the Imprimis engine is to provide a clean, documented and consistent base with which to build games, particularly first person shooter games, upon. It is currently under development and does not necessarily currently accomplish all the goals it has established here.
The engine is completely free and the engine code, game code, and assets are all licensed under permissive licenses.
Like Tesseract, Imprimis removes the static lightmapping system of Sauerbraten and replaces it with completely dynamic lighting system based on deferred shading and shadowmapping.
The Imprimis engine, however, focuses on providing universally destroyable geometry by leveraging the octree geometry system to conduct geometry modification on the fly, enabling gameplay mechanics not readily available to widely available engines such as realtime world construction and destruction.
Imprimis' Tesseract base provides a bunch of new rendering features such as:
- deferred shading
- omnidirectional point lights using cubemap shadowmaps
- perspective projection spotlight shadowmaps
- orthographic projection sunlight using cascaded shadowmaps
- HDR rendering with tonemapping and bloom
- real-time diffuse global illumination for sunlight (radiance hints)
- volumetric lighting
- screen-space ambient occlusion
- screen-space reflections and refractions for water and glass
- screen-space refractive alpha cubes
- deferred MSAA, subpixel morphological anti-aliasing (SMAA 1x, T2x, S2x, and 4x), FXAA, and temporal AA
- runs on OpenGL 4.0+ contexts
- support for Windows and Linux operating systems
For documentation on the engine, see doc/engine.md.
Imprimis is primarily a first-person shooter engine, though it can plausibly be used for other 3D cases. Its recursive octree subdivision geometry method and realtime rendering method is a very powerful generalized way of implementing realtime general (destroy any part of the world and have it be modified procedurally) world destruction. As a result, it is especially strong at:
- Realtime, generalized, procedural geometry modification
- Realtime modification of world lighting
- Good scalability to medium-sized maps (up to ~1km*1km)
- Performance on moderate-performance hardware such as modern integrated graphics
- Small, managable codebase
- Straightforward, integrated level editor
The Imprimis engine, however, may not be as suitable for other roles commonly targeted by other available engines:
- Distance culled, very large world rendering
- Large amounts of complex geometry detail or compound curvature
- Largely static levels without much geometry modification
- Low performance or legacy graphics support
In general, Imprimis is a relatively specialized engine which is useful largely for a class of game mechanics not accessible to other available engines. In the goals which Imprimis specifically targets (realtime geometry modification), there are not many available solutions that can replicate Imprimis' utility.
To get the game, git is required. Using git, get the repository and its sumodules with
git clone https://github.com/project-imprimis/imprimis.git --recurse-submodules
The imprimis folder will now be visible in the current directory.
To compile the game, use make -C src install -jN from the directory in which this file is located.
Set N to the number of threads to compile with. For example, for a quad-core processor, set -j4.
(to reach this directory use cd imprimis)
This game requires libsdl2, libsdl2-image, libsdl2-mixer, and drivers for OpenGL (usually already installed).
To compile the game, the development versions of the libraries are required (on distros that seperate standard and dev packages).
The game can then be run with ./imprimis_unix or ./imprimis.bat scripts, located in the same
directory as this readme file.
Imprimis is an open source project created by volunteers who work on the game as a hobby, and we'd love for it to be your hobby too! The Imprimis project tries to be well documented and transparent in its decision making so as to make outside participation fruitful. If you'd like to express your opinions on the engine's decision, modify the engine, participate on the engine code, or just say hello to the developers, that's great! We have a Discord server where you may interact with us at https://discord.gg/WVFjtzA.
To facilitate getting started working on Imprimis, there are several issues posted on the "issues" board. Whether you're a longtime open source contributor or you need to create a GitHub account to start participating, feel free to use issues labeled as "good first issue" to ask whatever questions you have about Git semantics or quirks about our specific codebase in order to get comfortable!