game2

My second exploration into 3D game engine programming with C++.

Overview

Renders a scene with multiple animated models, a controllable character and camera, a skybox, and shadow mapping. The purpose of this project was to gain exposure to the lower level tools used in game engine programming, with a focus on construction rather than architecture.

Demo 1

Main.Window.2026-03-14.14-06-25.mp4

Demo 2

Main.Window.2026-03-14.14-07-11.mp4

Toolchain

• Win32 API
• DirectX 11 rendering pipeline
• Custom STL-compatible block memory allocator: calvinsomething/memory_allocator;
• assimp/assimp asset loading library
• nothings/stb image loader (for panoramic skybox .hdr image)

Features

• 3D models loaded from .fbx, .obj, .mtl, and .dds files
• Skeletal animation
• Shadow map pass
• Skybox (equirectangle-to-cubemap projection via compute shader)
• Instanced rendering
• Normal mapping using tangent and bitangent vectors
• Structured buffers for materials and bone transforms
• Collision system (floor triangle detection)
• Steady frame rate and synced movement speed
• Error and debug message system using IDXGIDebug and ID3D11Debug

Retrospective

What Worked

• My custom allocator is fast and has no noticeable bugs at this point.
• The error system works well, is easy to use and provides valuable feedback in a convenient message box.
• The controls and the input->controller->entity pipeline is clean and easy to understand. I think it's a good foundation for a more sophisticated controls system.
• The collision system is minimal, but is still over-engineered for this scene. It efficiently stores terrain triangles in a sparse grid, depending on their slope, for cheap floor collision queries. Adding dynamic, 3D collision, would be a significant addition, but I think the current design is a strong starting point.
• The designs of Model, Mesh, Material, Animation, and Bone classes have some redeeming aspects. Referencing the vertices, indices, textures and bone transforms, rather than storing them internally, was a successful data oriented design choice.

What I Would Improve

• I would definitely add a rendering layer and attempt a render graph. The main loop should only be calling the most high level functions.
• The Model class should not be templated on the vertex type, and I would probably implement something more along the lines of a component system to group varying Mesh types under the same Model.
• I would define systems and manager classes to support further data oriented design, encapsulating the details of data loading and access.
• Assimp data should be copied entirely, freeing the aiScene afterwards.
• By implementing the shadow pass, I learned how an SoA design can be useful, and I would separate the vertex properties into their own buffer slots. This way the positions and bone data could be front-loaded and many vertex layouts could share the same shadow map vertex shader.
• Structured buffers would be cleaner than instancing for the purposes of this scene. I just wanted to implement instancing.
• The light source's projective matrix should be dynamic, and fitted around the camera's frustum. For this small scene I get away with a static transform, but for a larger area I would need a cascaded shadow map.
• Writing shader permutations would reduce the amount of HLSL, and make it easier to create and maintain shaders.

BUILDING

Requirements

• Windows SDK
• MSVC (version >= 19.15) and dxc
• cmake
• ninja (unless you want to use another build tool and stray from these build instructions)

If compiling shaders outside of Visual Studio, from your terminal you should execute the file vcvars64.bat located in a directory similar to this (depending on the version of Visual Studio): C:\Program Files\Microsoft Visual Studio\<year>\Community\VC\Auxiliary\Build. This will configure several environment variables Windows requires to run dxc from the command line.

Assimp

$ git clone https://github.com/assimp/assimp.git --branch v6.0.4
$ mkdir assimp\build && cd assimp\build
$ cmake -GNinja ..
$ ninja
$ xcopy lib <project-root>\vendor\lib\assimp /i
$ xcopy bin <project-root>\vendor\bin\assimp /i
$ xcopy ..\include\assimp <project-root>\vendor\include\assimp /s /i
$ xcopy include\assimp <project-root>\vendor\include\assimp /y

Free Models Used

poly.pizza

• Ninja
• Grass Platform

free3d.com

• Spider