Method raycast

src/collision/shapes/ConvexMeshShape.cpp:107–182

Raycast method with feedback information This method implements the technique in the book "Real-time Collision Detection" by Christer Ericson.

/// This method implements the technique in the book "Real-time Collision Detection" by
/// Christer Ericson.
bool ConvexMeshShape::raycast(const Ray& ray, RaycastInfo& raycastInfo, Collider* collider, MemoryAllocator& /*allocator*/) const {

    // Ray direction
    Vector3 direction = ray.point2 - ray.point1;

    decimal tMin = decimal(0.0);
    decimal tMax = ray.maxFraction;
    Vector3 currentFaceNormal;
    bool isIntersectionFound = false;

    const HalfEdgeStructure& halfEdgeStructure = mConvexMesh->getHalfEdgeStructure();

    // For each face of the convex mesh
    for (uint32 f=0; f < mConvexMesh->getNbFaces(); f++) {

        const HalfEdgeStructure::Face& face = halfEdgeStructure.getFace(f);
        const Vector3& faceNormal = getFaceNormal(f);
        const HalfEdgeStructure::Vertex& faceVertex = halfEdgeStructure.getVertex(face.faceVertices[0]);
        const Vector3& facePoint = mConvexMesh->getVertex(faceVertex.vertexPointIndex);
        decimal denom = faceNormal.dot(direction);
        decimal planeD = faceNormal.dot(facePoint);
        decimal dist = planeD -  faceNormal.dot(ray.point1);

        // If ray is parallel to the face
        if (denom == decimal(0.0)) {

            // If ray is outside the clipping face, we return no intersection
            if (dist < decimal(0.0)) return false;
        }
        else {

            // Compute the intersection between the ray and the current face plane
            decimal t = dist / denom;

            // Update the current ray intersection by clipping it with the current face plane
            // If the place faces the ray
            if (denom < decimal(0.0)) {
                // Clip the current ray intersection as it enters the convex mesh
                if (t > tMin) {
                    tMin = t;
                    currentFaceNormal = faceNormal;
                    isIntersectionFound = true;
                }
            }
            else {
                // Clip the current ray intersection as it exits the convex mesh
                if (t < tMax) tMax = t;
            }

            // If the ray intersection with the convex mesh becomes empty, report no intersection
            if (tMin > tMax) return false;
        }
    }

    if (isIntersectionFound) {

        // The ray intersects with the convex mesh
        assert(tMin >= decimal(0.0));