constants.h

// SPDX-FileCopyrightText: 2025 Erin Catto
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include "base.h"

B3_API void b3SetLengthUnitsPerMeter( float lengthUnits );

B3_API float b3GetLengthUnitsPerMeter( void );

B3_API void b3SetStallThreshold( float seconds );

B3_API float b3GetStallThreshold( void );
 
// Used to detect bad values. In float mode positions greater than about 16km have precision
// problems, so 100km is a safe limit. Large world mode keeps coordinates accurate much farther
// from the origin, so the sanity limit widens to keep valid far-field positions from tripping it.
#if defined( BOX3D_DOUBLE_PRECISION )
#define B3_HUGE ( 1.0e9f * b3GetLengthUnitsPerMeter() )
#else
#define B3_HUGE ( 1.0e5f * b3GetLengthUnitsPerMeter() )
#endif

#define B3_MAX_WORKERS 32

#define B3_MAX_TASKS 256
 
// Maximum number of colors in the constraint graph. Constraints that cannot
// find a color are added to the overflow set which are solved single-threaded.
// The compound barrel benchmark has minor overflow with 24 colors
#define B3_GRAPH_COLOR_COUNT 24
 
// Number of contact point buckets for counting the number of contact points per
// shape contact pair. This is just for reporting and doesn't affect simulation.
#define B3_CONTACT_MANIFOLD_COUNT_BUCKETS 8
 
// A small length used as a collision and constraint tolerance. Usually it is
// chosen to be numerically significant, but visually insignificant. In meters.
// @warning modifying this can have a significant impact on stability
#define B3_LINEAR_SLOP ( 0.005f * b3GetLengthUnitsPerMeter() )
 
#define B3_MIN_CAPSULE_LENGTH ( B3_LINEAR_SLOP )

#define B3_OVERLAP_SLOP ( 0.1f * B3_LINEAR_SLOP )

#ifndef B3_MAX_WORLDS
#define B3_MAX_WORLDS 128
#endif

#define B3_MAX_ROTATION ( 0.25f * B3_PI )

#define B3_SPECULATIVE_DISTANCE ( 4.0f * B3_LINEAR_SLOP )

#define B3_MESH_REST_OFFSET ( 1.0f * B3_LINEAR_SLOP )

#define B3_CONTACT_RECYCLE_DISTANCE ( 10.0f * B3_LINEAR_SLOP )

#define B3_CONTACT_RECYCLE_ANGULAR_DISTANCE ( 0.99240388f )

#define B3_MAX_AABB_MARGIN ( 0.05f * b3GetLengthUnitsPerMeter() )

#define B3_AABB_MARGIN_FRACTION 0.125f

#define B3_TIME_TO_SLEEP 0.5f

#ifndef B3_BODY_NAME_LENGTH
#define B3_BODY_NAME_LENGTH 18
#endif

#ifndef B3_SHAPE_NAME_LENGTH
#define B3_SHAPE_NAME_LENGTH 18
#endif

#define B3_MAX_MANIFOLD_POINTS 4

#define B3_MAX_SHAPE_CAST_POINTS 64

#define B3_SHAPE_POWER 22
#define B3_CHILD_POWER ( 64 - 2 * B3_SHAPE_POWER )
#define B3_MAX_SHAPES ( 1 << B3_SHAPE_POWER )
#define B3_MAX_CHILD_SHAPES ( 1 << B3_CHILD_POWER )