compute_path_tangents()

std::vector< Nodes::LineVertex > MayaFlux::Kinesis::compute_path_tangents	(	const std::vector< Nodes::LineVertex > &	path_vertices,
		float	tangent_length,
		size_t	stride = 1
	)

Compute tangent vectors along a piecewise-linear path.

Parameters

path_vertices	Sequential vertices defining curve
tangent_length	Magnitude of tangent vectors
stride	Sample every stride-th vertex

Returns

Line segments (pairs) representing tangents (for LINE_LIST topology)

Tangent at vertex i: direction (v[i+1] - v[i]) Returned as pairs: [vertex - tangent/2, vertex + tangent/2]

Definition at line 282 of file GeometryPrimitives.cpp.

{
    if (path_vertices.size() < 2 || stride == 0) {
        return {};
    }
 
    std::vector<Nodes::LineVertex> tangents;
    tangents.reserve((path_vertices.size() - 1) / stride * 2);
 
    for (size_t i = 0; i < path_vertices.size() - 1; i += stride) {
        glm::vec3 p0 = path_vertices[i].position;
        glm::vec3 p1 = path_vertices[i + 1].position;
 
        glm::vec3 tangent = p1 - p0;
        float length = glm::length(tangent);
 
        if (length < 1e-6F) {
            continue;
        }
 
        tangent = glm::normalize(tangent) * tangent_length;
 
        glm::vec3 color = path_vertices[i].color;
        float thickness = path_vertices[i].thickness;
 
        tangents.push_back({ .position = p0 - tangent * 0.5F,
            .color = color,
            .thickness = thickness });
 
        tangents.push_back({ .position = p0 + tangent * 0.5F,
            .color = color,
            .thickness = thickness });
    }
 
    return tangents;
}