`reducepatch`

Reduces the number of faces of a patch while trying to keep its shape.

Syntax

fv = reducepatch(fv0, r)

Returns a patch structure with about the fraction r of the faces of fv0.

reducepatch(p, r)

Reduces the patch with handle p in place.

[f, v] = reducepatch(F, V, r)

Works on separate face and vertex arrays.

Description

Large isosurfaces can have hundreds of thousands of triangles and be slow to draw. reducepatch merges them, mostly in flat regions, so the picture looks much the same with far fewer faces. The result is an approximation: the number of faces obtained can be somewhat different from the requested one.

Input arguments

fv0: Structure with faces and vertices, such as the output of isosurface.
r: Target fraction of faces if between 0 and 1, or a target number of faces if greater than 1.

Output arguments

fv: Structure with the reduced faces and vertices.

Example

Halve an isosurface

[x, y, z] = meshgrid(-1:0.25:1);
v = x.^2 + y.^2 + z.^2;
fv = isosurface(x, y, z, v, 0.5);
r = reducepatch(fv, 0.5);
size(r.faces, 1) < size(fv.faces, 1)

Output

ans = logical
   1

reducepatch