Methods

{
  "name": "RayTraceDetection",
  "namespace": "sofa::component::collision::detection::algorithm",
  "module": "Sofa.Component.Collision.Detection.Algorithm",
  "include": "sofa/component/collision/detection/algorithm/RayTraceDetection.h",
  "doc": "Collision detection using TriangleOctreeModel.\n\nIt is a Ray Trace based collision detection algorithm\n  For each point in one object, we trace a ray following the opposite of the point's normal\n  up to find a triangle in the other object. Both triangles are tested to evaluate if they are in\n  colliding state. It must be used with a TriangleOctreeModel,as an octree is used to traverse the object.",
  "inherits": [
    "BaseObject"
  ],
  "templates": [],
  "data_fields": [],
  "links": [],
  "methods": [
    {
      "name": "init",
      "return_type": "void",
      "params": [],
      "is_virtual": true,
      "is_pure_virtual": false,
      "is_static": false,
      "access": "public"
    }
  ],
  "description": "The `RayTraceDetection` component in the SOFA framework is designed for collision detection using TriangleOctreeModel, which employs ray-tracing techniques to identify collisions between objects. For each point on one object, it traces a ray opposite to the point's normal until it finds an intersecting triangle on another object. This intersection evaluation determines whether the triangles are in a colliding state.\n\nThis component inherits from `BaseObject` and interacts with other components through its initialization method (`init`). It must be used with a TriangleOctreeModel, leveraging octrees to traverse objects efficiently.\n\nIn practical usage, `RayTraceDetection` is deprecated and users are advised to use a combination of BroadPhase and NarrowPhase collision detection components instead. The component automatically adds `BruteForceBroadPhase` and `RayTraceNarrowPhase` for backward compatibility.",
  "maths": "The `RayTraceDetection` component in the SOFA framework is designed for collision detection using ray-tracing techniques. It operates on TriangleOctreeModel objects to identify collisions between points and triangles across different objects. Here is a detailed mathematical and physical description of this component:\n\n### Governing Equations or Operators\n\n- **Ray Tracing:** For each point \\( p_i \\) on one object, the component traces a ray in the direction opposite to its normal vector \\( \boldsymbol{n}_i \\). Mathematically, the ray is defined as:\n  \n  \n  \begin{align*}\n    R(t) = p_i + t (-\boldsymbol{n}_i), \\quad t > 0\n  \\end{align*}\n  where \\( t \\) is a scalar parameter indicating the distance along the ray.\n  \n- **Intersection Evaluation:** The component checks for intersections of this ray with triangles in another object. If an intersection occurs, it evaluates whether the intersecting triangles are in a colliding state based on their geometric proximity and orientation.\n\n### Constitutive or Kinematic Laws Involved\n\nThe `RayTraceDetection` component does not directly involve constitutive laws (e.g., strain measures, stress tensors) since its primary function is collision detection rather than material behavior simulation. However, it relies on the following kinematic principles:\n- **Normals and Rays:** The normal vector \\( \boldsymbol{n}_i \\) at each point \\( p_i \\) is used to define the direction of the ray.\n\n### Role in the Global FEM Pipeline\n\nThe `RayTraceDetection` component primarily contributes to the collision detection phase within the broader simulation pipeline:\n- **Collision Detection:** It identifies potential collisions between objects by tracing rays from points on one object towards another. This information is crucial for enforcing constraints and contacts during the nonlinear solve and linear solve stages of the FEM process.\n\n### Numerical Methods or Discretization Choices\n\nThe component leverages octrees (TriangleOctreeModel) to efficiently traverse and search for intersections, which provides a spatial data structure to accelerate collision detection:\n- **Ray Tracing Algorithm:** The algorithm traces rays from each point on one object in the direction opposite to its normal until it finds an intersection with a triangle on another object.\n\n### Integration into Variational / Lagrangian Mechanics Framework\n\nAlthough `RayTraceDetection` itself is not directly involved in the variational formulation or Lagrangian mechanics, collision detection plays a critical role in enforcing constraints and maintaining physical consistency within the simulation framework:\n- **Constraints Handling:** The detected collisions inform constraint enforcement mechanisms (e.g., Lagrange multipliers) used to maintain contact conditions between objects during time integration.\n\n### Deprecation Notice\n\nThe `RayTraceDetection` component is deprecated, and users are advised to use a combination of BroadPhase and NarrowPhase collision detection components instead. This modern approach provides better scalability and performance for large-scale simulations.\n\nOverall, the `RayTraceDetection` component serves as an efficient ray-tracing based mechanism for detecting collisions between objects in SOFA, contributing to the broader simulation framework's robustness and physical consistency.",
  "abstract": "The `RayTraceDetection` component performs ray-tracing based collision detection between objects using TriangleOctreeModel. It traces rays from points on one object in the direction opposite to their normals to find intersections with triangles on another object.",
  "sheet": "<h1>RayTraceDetection</h1>\n\n<h2>Overview</h2>\n<p>The `RayTraceDetection` component performs ray-tracing based collision detection between objects using TriangleOctreeModel. It traces rays from points on one object in the direction opposite to their normals to find intersections with triangles on another object. This component is deprecated, and users are advised to use a combination of BroadPhase and NarrowPhase collision detection components instead.</p>\n\n<h2>Mathematical Model</h2>\n<p>The ray tracing algorithm traces rays from each point \\( p_i \\) on one object in the direction opposite to its normal vector \\( \\boldsymbol{n}_i \\). Mathematically, the ray is defined as:</p>\n\\[ R(t) = p_i + t (-\\boldsymbol{n}_i), \\quad t > 0 \\]\n<p>where \\( t \\) is a scalar parameter indicating the distance along the ray. The component checks for intersections of this ray with triangles in another object and evaluates whether the intersecting triangles are in a colliding state based on their geometric proximity and orientation.</p>\n\n<h2>Dependencies and Connections</h2>\n<p>The `RayTraceDetection` component must be used with a TriangleOctreeModel, as an octree is used to traverse objects efficiently. It automatically adds `BruteForceBroadPhase` and `RayTraceNarrowPhase` for backward compatibility.</p>"
}