Struct QemDecimation 

pub struct QemDecimation {
    pub mesh: SimpleMesh,
    /* private fields */
}

A QEM-based decimator that wraps SimpleMesh and provides adaptive error thresholds, boundary preservation, and feature scoring.

Fields

mesh: SimpleMesh

The mesh being simplified.

Implementations

impl QemDecimation

pub fn new(mesh: SimpleMesh) -> Self

Construct a QemDecimation from a mesh. Quadrics are computed once.

pub fn recompute_quadrics(&mut self)

Recompute the per-vertex quadric matrices from the current mesh.

pub fn compute_error_threshold(&self, scale_factor: f64) -> f64

Compute an adaptive QEM error threshold.

The threshold is scale_factor * avg_edge_length² * mean_curvature_proxy, where the mean curvature proxy is the average edge collapse cost over a sample of edges. This adapts the threshold to mesh scale and feature density.

scale_factor controls aggressiveness (try 0.01 – 1.0).

pub fn preserve_boundary(&mut self, threshold: f64) -> usize

Collapse edges while preserving boundary geometry.

Boundary edges (shared by exactly one triangle) are never collapsed. Interior edges with QEM cost below threshold are collapsed greedily using a priority queue.

Returns the number of collapses performed.

pub fn compute_feature_score(&self) -> HashMap<(usize, usize), f64>

Compute a feature importance score for each edge in the mesh.

The score is the sum of the dihedral-angle curvature between the two incident faces. High scores indicate sharp creases or geometric features that should be preserved.

Returns a HashMap<(usize, usize), f64> keyed by the canonical (min, max) vertex index pair.