yuki-koyama / bigger

bigg (bgfx + imgui + glfw + glm) + utils

bigger

bigg (bgfx + imgui + glfw + glm) + utils

This library, named bigger, is a prototype-oriented middleware library for 3D interactive applications. Based on a library named bigg, which stands for bgfx + imgui + glfw + glm, this library adds some higher-level utilities (such as renderable primitive classes) to make the prototyping of lightweight and cross-platform apps even easier.

Languages

• C++17
• GLSL 1.30

Dependencies

• bigg https://github.com/Josh4428/bigg [Unlicense]
  • bgfx.cmake https://github.com/widberg/bgfx.cmake [CC0 1.0 Universal]
    • bgfx https://github.com/bkaradzic/bgfx [BSD 2-Clause]
    • bimg https://github.com/bkaradzic/bimg [BSD 2-Clause]
    • bx https://github.com/bkaradzic/bx [BSD 2-Clause]
  • Dear ImGui https://github.com/ocornut/imgui [MIT]
  • GLFW https://github.com/glfw/glfw [Zlib]
  • GLM https://github.com/g-truc/glm [MIT]
• random-util https://github.com/yuki-koyama/rand-util [MIT]
• string-util https://github.com/yuki-koyama/string-util [MIT]
• tinyobjloader https://github.com/tinyobjloader/tinyobjloader/ [MIT]

Main Classes

• App (needs to be overridden)
• Camera
• Primitives
  • Cube primitive
  • Dynamic mesh primitive
  • Mesh primitive
  • Plane primitive
  • Sphere primitive
• Materials
  • Blinn-Phong material
  • MatCap material

App Event Cycle

• bigger::App::runApp()
  • bigg::Application::run()
    • glfw initialization
    • bgfx initialization
    • imgui initialization
    • Reset
    • bigger::App::initialize() (needs to be overridden)
    • Main loop
      • glfw event polling
      • imgui event polling
      • bigger::App::update()
        • bigger::App::updateApp() (needs to be overridden)
        • Update scene objects (bigger::SceneObject::update())
        • Render scene objects (bigger::SceneObject::draw())
      • imgui render
      • bgfx submit
    • bigger::App::shutdown()
      • Release scene objects
      • bigger::App::releaseSharedResources() (needs to be overridden)
    • imgui shutdown
    • bgfx shutdown
    • glfw shutdown

App Design

• Always two directional lights
  • Other types of lights or more than two directional lights are not supported
• Intensive use of smart pointers
  • Primitives and materials need to be dynamically instantiated and managed by smart pointers (i.e., either std::shared_ptr<T> or std::unique_ptr<T>)

Usage

Minimal Example

This is a minimal example of using bigger::App. This app just shows a blank window and do nothing.

#include <bigger/app.hpp>

class MinimalApp final : public bigger::App
{
public:

    MinimalApp() {}

    void initialize(int argc, char** argv) override {}
    void updateApp() override {}
    void releaseSharedResources() override {}
};

int main(int argc, char** argv)
{
    MinimalApp app;
    return app.runApp(argc, argv);
}

Override App Class

The following three methods need to be overridden by the new app class:

• bigger::App::initialize(): Initializing the app and instantiating necessary objects living through the app life.
• bigger::App::updateApp(): Writing frame-wise update rules and calling imgui draw calls.
• bigger::App::releaseSharedResources(): Releasing shared resources maintained by the app class (such as vertex buffers).

(TODO)

Additional Notes: Screen Capture

bgfx provides screen capture functionalities, which of course can be directly called (see the official documentation and examples). For easier use, in bigger by default, just inserting the following one-line code into update() can capture the screen:

bgfx::requestScreenShot(BGFX_INVALID_HANDLE, "/path/to/output");

Note: On macOS, using the Metal backend somehow fails to capture the screen (not sure why; probably related to this issue). A possible quick fix is to use OpenGL.

License

MIT License

Contribution

Issue reports & pull requests are highly welcomed.