acdemiralp / magpie

A minimalistic rendering engine based on ImGui and Im3d.

Magpie - Minimalist Visualization Engine

Approximately 15 minutes to setup, including downloading and installing the dependencies.

Motivation

I needed a C++ library/engine to in-situ visualize numeric compute as points/lines/triangles, and configure it using a basic UI. Unity3D and Unreal are not particularly efficient at immediate rendering, and are hard to couple with external dependencies. ParaView/Catalyst stack requires a lot of configuration, and is too heavyweight for the purpose. Hence, I decided to recycle parts of a never-published game engine, leading to this project.

Requirements

• A C++17 Compiler (Clang 5+, GCC 7+ or MSVC 14.1+)
• CMake 3.11+
• Conan 1.1+
• Git

Building

• Download and install the requirements above.
• CMake. The majority of the dependencies will be downloaded, built and linked automatically via Conan through Bintray.

Usage

Three lines to create a window, and setup an OpenGL rendering system:

#include <magpie/api.hpp>
#include <magpie/graphics/backend/opengl/render_tasks.hpp>
int main (int argc, char** argv)
{
  auto engine = mp::make_default_engine();
  auto window = engine->system<mp::display_system>()->create_opengl_window("Example", di::opengl_context_settings{di::opengl_profile::core, 4, 5});
  mp::opengl::make_default_framegraph(engine.get(), window);
}

You may then create an entity with a behavior and use Im3d or ImGui commands as following:

auto entity    = engine->scene()->add_entity();
auto behaviors = entity->add_component<mp::behaviors>();
behaviors->push_back(std::make_shared<mp::behavior>(
[&] (                                    mp::scene* scene, mp::entity* entity)
{

},
[ ] (mp::frame_timer::duration duration, mp::scene* scene, mp::entity* entity)
{
  ImGui::SetCurrentContext(mp::imgui_context());
  ImGui::Begin            ("FPS");
  ImGui::Text             ("%.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
  ImGui::End              ();
}));

See tests/engine_test.cpp for further detail.