Revised chain shape

[erincatto]

• API Breaking
• Revised chain shape to be segment based. Materials are now associated with segments rather than points. Leading and trailing ghost points are separate for open chains.
• b2Profile and b2Counters structs are under ! @cond guard #1092
• b2SolvePlanes has no unit-test coverage (test available) #1103
• b2Chain_SetSurfaceMaterial writes out of bounds on an open chain with per-point materials #1091
• Bug: ShapeDistance not working correctly in sample_collision #1090
• Build fails with Clang on macOS because of wrong C++ standard version #1089
• Compilation times: avoiding <math.h> in headers #1079

[Copilot]

🟡 Changes recommended

The Chain Shape sample’s friction control now updates only one segment instead of the complete chain.

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Pull request overview

Reworks chain shapes around explicit segments and ghost points while incorporating related API, testing, portability, and documentation fixes.

Changes:

• Redesigns chain geometry/material APIs and updates snapshots and recordings.
• Adds chain and mover regression tests.
• Splits math types from functions and consolidates platform/SIMD utilities.

File summaries

File	Description
test/test_table.c	Updates includes and formatting.
test/test_snapshot.c	Migrates snapshot chain setup.
test/test_recording.c	Tests new chain material operations.
test/test_mover.c	Adds plane-solver tests.
test/test_macros.h	Exposes the test assertion handler.
test/test_chain.c	Adds chain geometry/material tests.
test/main.c	Registers new tests and assertion handling.
test/CMakeLists.txt	Adds new test sources.
src/world_snapshot.c	Serializes revised chain state.
src/wheel_joint.c	Removes an unused include.
src/types.c	Initializes ghost-point sentinels.
src/timer.c	Narrows Windows header features.
src/table.h	Removes platform-specific helpers.
src/table.c	Uses consolidated platform utilities.
src/solver.c	Updates internal dependencies.
src/simd.h	Extracts AABB SIMD helpers.
src/shape.h	Simplifies chain storage.
src/shape.c	Implements segment-based chains and materials.
src/sensor.c	Uses consolidated platform utilities.
src/scheduler.c	Updates platform dependencies.
src/recording.h	Updates recording format and includes.
src/recording.c	Records ghost points and point counts.
src/recording_replay.c	Replays revised chain operations.
src/recording_ops.inl	Adds broadcast material recording.
src/prismatic_joint.c	Removes an unused include.
src/platform.h	Consolidates atomics and bit operations.
src/physics_world.c	Adapts world logic to revised chains.
src/parallel_for.c	Uses consolidated platform utilities.
src/dynamic_tree.h	Moves SIMD implementation out.
src/dynamic_tree.c	Includes extracted SIMD helpers.
src/ctz.h	Removes superseded bit utilities.
src/core.c	Uses consolidated platform utilities.
src/container.h	Uses MSVC-specific string declarations.
src/CMakeLists.txt	Registers new headers and MSVC options.
src/broad_phase.h	Removes unnecessary dependencies.
src/broad_phase.c	Localizes prefetch and SIMD helpers.
src/aabb.h	Adds required math functions.
shared/benchmarks.c	Migrates chain point-count usage.
samples/sample_world.cpp	Migrates chain definitions.
samples/sample_shapes.cpp	Migrates chain geometry.
samples/sample_joints.cpp	Migrates chain definitions.
samples/sample_events.cpp	Separates open-chain ghost points.
samples/sample_continuous.cpp	Migrates chain definitions.
samples/sample_collision.cpp	Migrates chains and fixes no-hit casting.
samples/sample_character.cpp	Migrates chain definitions.
samples/CMakeLists.txt	Propagates C++20 requirements.
include/box2d/types.h	Revises chain and profiling APIs.
include/box2d/math_types.h	Adds lightweight math types.
include/box2d/math_functions.h	Uses the extracted math types.
include/box2d/id.h	Improves generated documentation.
include/box2d/collision.h	Depends only on math types.
include/box2d/box2d.h	Revises chain material APIs.
include/box2d/base.h	Documents version components.
docs/simulation.md	Updates chain examples and guidance.
docs/recording.md	Corrects the snapshots heading.
build.zig	Registers new tests.
.github/ISSUE_TEMPLATE/issue.md	Adds the issue template.
.github/ISSUE_TEMPLATE/config.yml	Configures issue intake.
.github/issue_template.md	Removes the legacy template.

Review details

• Files reviewed: 59/59 changed files
• Comments generated: 1
• Review effort level: Balanced

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