Popcorn Engine

This is my attempt to learn Computer Graphics with Vulkan after many years of working with WebGL and ThreeJS. I hope to write a game like INSIDE (2016) by Playdead one day with Popcorn. I am mainly focusing on the behaviour of lights and how the interact with material surfaces. I am modelling my API after ThreeJS, because I really like it's easy to use but flexible API.

Currently working on

• Rasterized lighting integration (Deferred lighting)
• Raytracing integration

Demo (last significant update)

Features

• Vulkan-based rendering pipeline
• Deferred rendering with G-buffer and lighting pass
• Support for PBR and basic material types
• TinyGLTF integration for loading Blender models with vertex colors

Installation

Enter these commands for installation on linux.

git clone https://github.com/pravasith/popcorn.git
cd popcorn/Engine/
./scripts/linux-setup.sh

Build

After the setup, if you wish to build for linux or windows (cross-compile), enter these commands for installation on linux.

git clone https://github.com/pravasith/popcorn.git
cd popcorn/Engine/
./scripts/build.sh

In the prompt, enter 'l' for linux build, and 'w' for a windows build.

Sandbox

To create a application/game with Popcorn engine, simply copy any example sandbox folder, rename it and modify the main.cpp file to get started.

The API for usage looks like this (in this example, we are making a simple rotating cube) - You can create Layers and use the useful methods like OnEvent(), OnUpdate() and OnRender() methods

using namespace Popcorn;

class GameLayer : public Layer {
  class TriangleScene : public Scene {};

public:
  GameLayer() {};
  ~GameLayer() {};

  virtual void OnAttach() override {
    // Create VertexBuffer
    vertexBuffer = VertexBuffer::Create();
    // Create 
    indexBuffer = new IndexBuffer<uint16_t>();

    vertexBuffer->SetLayout<BufferDefs::AttrTypes::Float3,
                            BufferDefs::AttrTypes::Float3>();

    // Single quad data (shared by all cube faces)
    vertexBuffer->Fill<Vertex>({{{-0.5f, -0.5f, .0f}, {1.0f, 0.0f, 0.0f}},
                                {{0.5f, -0.5f, .0f}, {0.0f, 1.0f, 0.0f}},
                                {{0.5f, 0.5f, .0f}, {0.0f, 0.0f, 1.0f}},
                                {{-0.5f, 0.5f, .0f}, {1.0f, 1.0f, 1.0f}}});

    indexBuffer->Fill({0, 1, 2, 2, 3, 0});

    // Material setup
    std::vector shaderFiles{"shaders/tri_vert.spv", "shaders/tri_frag.spv"};
    MaterialData matData{(ShaderStages::VertexBit | ShaderStages::FragmentBit),
                         shaderFiles};
    triMat = new BasicMaterial(matData);

    mesh = new Mesh{*vertexBuffer, indexBuffer, *triMat};

    mesh->SetPosition({.0f, 1.f, 0.f});
    mesh->RotateX(glm::radians(-90.f));

    triScene.AddNode(mesh);

    auto &renderer = Popcorn::Context::GetRenderer();
    renderer.AddScene(&triScene);
  };

  virtual void OnDetach() override {
    delete triMat;
    triMat = nullptr;

    delete indexBuffer;
    indexBuffer = nullptr;

    VertexBuffer::Destroy(vertexBuffer);
    delete mesh;
  };

  virtual void OnUpdate(TimeEvent &e) override {
    mesh->RotateZ(glm::radians(90.f) * e.GetDeltaS());
    triScene.Update();
  };

  virtual void OnRender() override { Renderer::Get().DrawFrame(triScene); };

  virtual bool OnEvent(Event &e) override { return false; };

private:
  VertexBuffer *vertexBuffer;
  IndexBuffer<uint16_t> *indexBuffer;
  TriangleScene triScene;
  Mesh *mesh;
  Material *triMat;
};

// THE MAIN FUNCTION
int main(int argc, char **argv) {
  Popcorn::Context::Begin();

  auto gameLayer = new GameLayer();
  Application::AddLayer(gameLayer);

  Popcorn::Context::RunGame();

  Popcorn::Context::End();
  return 0;
}

Custom shaders

You can write your own shaders in assets/shaders/ folder and set their paths as strings while creating the material. Don't forget to compile your shaders with these commands (make sure you are in your sandbox folder -

cd Sandbox/YourGameAppFolder/ 
./scripts/compile-shaders.sh

Build your game

After the setup, if you wish to build for linux or windows (cross-compile), enter these commands for installation on linux.

cd Sandbox/YourGameAppFolder/ 
./scripts/build.sh

Run you game

The executables are created in the dist/linux/bin/ folder (for linux) and dist/windows/bin/ folder (for windows).