Upgrading to 3.0

FOSSIL 3.0 adds roadmap #68 (cut-cell solver support, curvilinear blocks, overset assembly, continuous collision detection, body-fitted grids), the documentation rebuild (#77, #85), and the fixes the documentation work exposed (#90, #91). No public name was removed or renamed: code that compiled against 2.2 compiles against 3.0. Some routines now behave differently, which is why the major version changes. This page lists every change in behaviour since 2.2.0, with its opt-out where one exists, then the public names that are new.

The changelog lists every commit.

Changes in behaviour

Routine	2.2	3.0	Opt-out	Issue
intersect_ray_first, _all, _any	Moller-Trumbore on the closed range: a ray through a shared edge or vertex hit every facet there (12 hits for 2 crossings through cube-01's face centres); the octree could lose hits	one hit per crossing, by exact tests with a symbolic tie-break; hits at t = 0 are kept; equal t sort by facet id, so _first equals _all(1)	_all(exclude=) skips a facet (the ray's own, for instance)	#82
isotropic_remesh	almost never collapsed an edge: it did not coarsen	coarsens (link condition), tangential relaxation, and every collapse, flip and move is refused when its facets leave the input by more than REMESH_ERROR_TOL = 0.07 L. Facet counts and deviations differ from 2.2	none (preserve_features unchanged)	#79, #91
decimate	collapses could leave zero-area facets and non-manifold edges with DEC_STATUS_OK; target_facets <= 0 returned an empty surface; patch rims never coarsened	link condition and zero-area refusal; target_facets <= 0 is DEC_STATUS_BAD_INPUT; patch rims coarsen along themselves onto input rim vertices (corners fixed); an unreachable target gives DEC_STATUS_NO_PROGRESS with a valid surface	rim_collapses=.false. locks the rims; max_error= (new, opt-in) is a cost ceiling	#81, #91
resolve_self_intersections	returned the arrangement unselected (volume counted twice, not closed) with BOOL_STATUS_OK	the self-union (patches of winding number 0 in front, Zhou et al.); BOOL_STATUS_NOT_CLOSED when the selection is open (the surface is left unchanged); triple crossings get a three-plane implicit point	none	#78
jet_curvature, query_many(curvatures=)	a rank-deficient fit silently kept the cotangent value (H = 7.4e9 on near-coincident rings)	near-coincident ring vertices merged, the ring grown; a fit that stays rank-deficient gives NaN and CURV_STATUS_FIT_FAILED	none	#91
extract_isosurface	node values missing the level by round-off produced zero-area slivers	such nodes are snapped to the level (within 1e-12 of their edge crossings): no slivers; other cells bit-identical	none	#87
fill_holes, sanitize	open_edges and the "boundary edges" warning counted non-manifold edges too	open_edges counts true boundary edges; nonmanifold_edges= reports the others; the filled surfaces are unchanged	manifold_only=.true. (new, opt-in; sanitize(manifold_holes=))	#88, #91
save_into_file	a binary save over a larger file kept its tail	the file is replaced	none	#80
patch_name (binary STL)	the 80-byte header with its NUL padding	the header cut at the first NUL; get_header keeps the raw bytes	none	#83
swept_cells_2d, swept_cells_3d	exact = .false. on some rotations whose residual was round-off	exact = .true. there; the values are unchanged	none	#84, #86
proximity_pairs_of	grew its result by self-referencing reshapes	allocates once; results bit-identical	none	#76

What to check in your code:

• Remesh and decimate outputs are different meshes: re-measure anything that depends on their facet counts or deviations. The isotropic remeshing and decimation pages give the new numbers.
• Code that counted ray hits to decide inside/outside, or merged equal-t hits by hand, can drop that workaround.
• Code that tested decimate's status gets DEC_STATUS_BAD_INPUT for a non-positive target and DEC_STATUS_NO_PROGRESS where 2.2 returned a broken surface with OK.
• Curvature consumers should accept NaN with CURV_STATUS_FIT_FAILED where 2.2 returned a meaningless number.
• resolve_self_intersections callers should handle BOOL_STATUS_NOT_CLOSED (open inputs).

New public names

All exported by use fossil unless noted; no name was removed or renamed.

• Cut-cell solver support (page): cut_links_t, cut_links_2d, srd_neighbourhoods, srd_t, SRD_*, frd_neighbourhoods, frd_t, merge_targets, merge_t, MERGE_*, cut_coarsen_2d, cut_coarsen_3d, MOMENTS_MAX, mono_count, mono_exponents; modules fossil_cut_graph, fossil_cut_moments, fossil_cut_coarsen; new arguments of cut_cells_3d (links=, edges=, moments_order=, quadrature=) and curve%cut_cells.
• Curvilinear blocks (page): curvilinear_block_t, curvilinear_block_2d_t, topo_record_t, TOPO_*, record_map, detect_topology(_2d), CELL_*, LOC_*, locate_in_blocks(_2d), STENCIL_*, block_real_t, block_logical_t, BLOCK_STATUS_*; modules fossil_curvilinear_block, fossil_block_geometry, fossil_block_locate, fossil_block_stencil.
• Overset assembly (page): wall_cutter(_2d) (strict trimming by default, strict=.false. for the centroid rule), hole_flags(_2d), hole_map(_2d), xray_flags(_2d), donor_candidates(_2d), donor_set_t, overlap_matrix(_2d), PAIR_*, classify(_2d), SELECT_*, overset_mask_t, ORPHAN_*, fringe_levels(_2d), FRINGE_*, overlap_width(_2d), wall_projection(_2d), exposed_points, cell_centre_block(_2d), connectivity_t, build_connectivity, save_connectivity; module fossil_overset.
• Collision (page): surface%time_of_impact (adaptive default; directional= forces the plain or the directional step), curve%time_of_impact, first_impact(_2d), motion_bound_3d/_2d, ccd_advance, ccd_evaluator_t, CCD_* (statuses, CCD_MAX_ITERATIONS, CCD_STALL_STEPS, CCD_STALL_FRACTION), safe_step; module fossil_ccd.
• Body-fitted grids (page): surface%projection_target, curve%projection_target, projection_target_t, PROJ_*, project_points(_2d), classify_points(_2d), project_block_face, project_block_side, block_report(_2d), block_report_t, save_block_report, utau_flat_plate, hyperbolic_grid_2d, geometric_spacing; modules fossil_projection, fossil_block_report, fossil_hyperbolic.
• Self-intersections and booleans: SELFINT_* kinds, BOOL_STATUS_NOT_CLOSED; the implicit point kind IPK_TPI (module fossil_implicit_points).
• Queries and trees: surface%tree_boxes, curve%tree_boxes; intersect_ray_all(exclude=).
• Processing: decimate(max_error=, rim_collapses=), REMESH_ERROR_TOL (module fossil_remesh), CURV_STATUS_FIT_FAILED, fill_holes(nonmanifold_edges=, manifold_only=), sanitize(manifold_holes=).

The documentation

The site was rebuilt around runnable examples: 16 tutorial chapters, 85 cookbook recipes (one for every entry point of the feature map), and a generated figure for every explaining section of the reference pages, 373 figures in all, every one computed by a program that runs when the docs are built.