Skye

A modern C++ game engine.

Getting Started

• Building the Project: On Windows, run the GenerateProjects.bat file to re-generate all visual studio sources files.

• Running the project: Open the visual studio solution file in Skye.sln, run the project with F5.

Project Structure

Submodules

In order to support external dependencies, I am using git submodules for the following, which all all stored in the /vendor sub-directory:

• spdlog: A fast c++ logging library
• GLFW: A helper library to support OpenGL rendering.
• imgui: A fast c++ gui library.
• glm: An all-purpose 3D math library.

Sandbox

This directory is an example Game that is built on the Skye engine. It creates and runs a Skye Application which provides all the necessary bindings to render objects.

Skye

This directory is the main entry point for the engine.

• Skye/src

  • We use precompiled headers in skpch.hpp for generic std library c++ functions.
  • Skye.hpp is the Skye API abstraction that applications using the engine should reference.

• Skye/src/Platform

  • Contains Graphics API abstractions so that the engine can be used with OpenGL, DirectX11, Vulkan, and DirectX12.
  • Each Graphics API abstractions is within its own directory , i.e. OpenGL.
  • Also contained in this directory is a Windows folder which contains Window specific rendering logic. (Will be only OS supported for now).

• Layers: I define a concept, called Layers, which are rendered to the screen via the supported Graphics API. Overlays are a specific layer type that are always rendered on-top. An example of an overlay is the IMGUI Debug menus that are rendered on top of the game layer.

• Mouse and Key Codes: In order to support other Graphics APIs, I define Skye mouse and keycodes to stray away from DirectX or OpenGL specific codes.

• Application: An instance of an application is created by users of the Skye engine, i.e. Sandbox. The Application classes provides the main source of calling the Skye Rendering API.

• Skye/src/Skye/Events Events: The input and layer levels will communicate through events. There are Application, Key and Mouse Events that will be dispatched to the Application for processing.

• Skye/src/Skye/ImGui ImGui is a ui library which we import as a submodule. I provide a wrapper around ImGui in order to more easily add and modify debug menus as an overlay.

• Skye/src/Skye/Renderer The generic Rendering API that is subclassed in the Platform directory. Classes in this directory should be subclassed per Graphics API (i.e. OpenGL,DirectX)

  • GraphicsContext: Grabs the graphics context based on the Graphics API in use.
  • Buffer: The generic buffer object which is subclassed for vertex and index buffers.
  • RenderCommand: A static abstract class that defines functions to render data from a vertex buffer.
  • Renderer: Defines more generic render functions that will focus on drawing an entire scene and not just a single mesh.
  • RendererAPI: Used to define the type of Graphics API in use.
  • Shader: Defines an abstraction to create, compile and use a shader program with a vertex and fragment shader.
  • VertexArray: Defines the concept of a vertex array that hold pointers to 1 or more vertex buffer and a single index buffer.

2D Sprite Sheet Render Example - Sandbox 2D

Sandbox2D is a sample class that utilizes the Skye game engine to render 2d sprites. Gameplay can be added in the OnUpdate() function, where each render pass is currently performed. Skye allows for rendering of 2d sprite, given a sprite sheet and coordinates on said spritesheet. The simple InmGui window shows the rendering statistics, as well as a selectable 2d texture that will draw on Left Mouse Click. My main goal for Skye was to learn the inner workings of a simple game engine in order to apply this knowledge to larger projects in UE5.