{
  "name": "CompositingVisualLoop",
  "main": {
    "name": "CompositingVisualLoop",
    "namespace": "sofa::gl::component::shader",
    "module": "Sofa.GL.Component.Shader",
    "include": "sofa/gl/component/shader/CompositingVisualLoop.h",
    "doc": "Visual loop enabling multipass rendering. Needs multiple fbo data and a compositing shader.\n\n\\Compositing visual loop: render multiple passes and composite them into one single rendered frame",
    "inherits": [
      "DefaultVisualManagerLoop"
    ],
    "templates": [],
    "data_fields": [],
    "links": [],
    "methods": [
      {
        "name": "init",
        "return_type": "void",
        "params": [],
        "is_virtual": true,
        "is_pure_virtual": false,
        "is_static": false,
        "access": "public"
      },
      {
        "name": "drawStep",
        "return_type": "void",
        "params": [
          {
            "name": "vparams",
            "type": "sofa::core::visual::VisualParams *"
          }
        ],
        "is_virtual": true,
        "is_pure_virtual": false,
        "is_static": false,
        "access": "public"
      }
    ]
  },
  "desc": {
    "description": "The `CompositingVisualLoop` is a visual management loop in the SOFA framework, specifically within the rendering and shader components (namespace: sofa::gl::component::shader). It enables multipass rendering by managing multiple frame buffer objects (FBOs) and utilizing a compositing shader to combine the results into a single rendered frame. This component inherits from `DefaultVisualManagerLoop` and implements methods like `init()` and `drawStep(VisualParams *)`, which are essential for initializing and drawing visual steps respectively, ensuring that multiple rendering passes can be effectively composited together."
  },
  "maths": {
    "maths": "The `CompositingVisualLoop` is a visual management loop in the SOFA framework, specifically designed to handle multipass rendering. This component does not contribute directly to the governing equations or operators related to FEM such as the mass matrix (\\(M\")), stiffness matrix (\\(K\")), internal force (\\(f_{int}\")), or residual (\\(R\")). Instead, it operates in the context of rendering and visualization, which are post-processing steps that occur after the simulation has been computed. \n\n### Role in the FEM Pipeline\n\nIn the broader variational / Lagrangian mechanics framework, `CompositingVisualLoop` plays a role in visualizing the results obtained from solving the nonlinear dynamic equations of deformable continua. Specifically:\n\n1. **Assembly Phase**: Although not directly involved in assembling global matrices or forces, it is indirectly related as its purpose is to render the state of the assembled system.\n2. **Time Integration and Nonlinear Resolution**: It does not influence these phases but rather visualizes the results from them.\n3. **Linear Solve and Update**: Similarly, it does not participate in the linear solve or update steps of the simulation pipeline.\n4. **Constraint Handling and Mapping**: These are handled by other SOFA components that deal with mechanical constraints and mappings; `CompositingVisualLoop` is only concerned with rendering these results.\n\n### Numerical Methods and Discretization Choices\n\nThe component implements multipass rendering, which involves the following steps:\n\n1. **Initialization (`init()` method)**: This method initializes the necessary resources for multiple frame buffer objects (FBOs) and prepares the compositing shader that will be used to combine these passes.\n2. **Rendering Passes (`drawStep(VisualParams *)` method)**: This method handles drawing each pass, which is essential for generating intermediate frames that are combined into a final rendered image using the compositing shader.\n\n### Mathematical and Physical Description\n\nSince `CompositingVisualLoop` is focused on rendering, it does not involve constitutive or kinematic laws directly. Its primary function is to handle the visual representation of the simulation results through multipass rendering techniques. The mathematical content here pertains more to computer graphics than FEM mechanics:\n\n1. **Frame Buffer Objects (FBOs)**: Each pass writes its output to a separate FBO, which can be thought of as intermediate buffers that store the state of the scene after each rendering step.\n2. **Compositing Shader**: This shader is responsible for combining multiple FBO outputs into one final rendered frame. The compositing process might involve operations like blending, filtering, or other image processing techniques to combine the intermediate frames.\n\nIn summary, `CompositingVisualLoop` plays a crucial role in visualizing the results of an FEM simulation through advanced rendering techniques but does not directly contribute to the core mathematical and physical components of the FEM framework."
  },
  "summary": {
    "abstract": "The `CompositingVisualLoop` enables multipass rendering by managing multiple frame buffer objects (FBOs) and utilizing a compositing shader to combine intermediate frames into a single final rendered image.",
    "sheet": "\n# CompositingVisualLoop\n\n**Overview**\nThe `CompositingVisualLoop` is a visual management loop in the SOFA framework that enables multipass rendering. It inherits from `DefaultVisualManagerLoop`, manages multiple frame buffer objects (FBOs), and uses a compositing shader to combine intermediate frames into one final rendered image.\n\n**Practical Notes**\nThe component requires proper initialization of FBOs and a correctly configured compositing shader for effective multipass rendering. Ensure that the visual parameters are set appropriately in each pass, and verify that the compositing shader is capable of handling the desired blending or filtering operations to combine the intermediate frames."
  }
}