HairSettings::Material Struct Reference

The material determines the simulation parameters for a hair strand. More...

#include <HairSettings.h>

Public Member Functions
bool	NeedsGrid () const
	Returns if this material needs a density/velocity grid.
bool	GlobalPoseOnly () const
	If this material only needs running the global pose logic.
float	GetBendCompliance (float inStrandFraction) const
	Calculate the bend compliance at a fraction along the strand.

Public Attributes
bool	mEnableCollision = true
	Enable collision detection between hair strands and the environment.
bool	mEnableLRA = true
	Enable Long Range Attachments to keep hair close to the modeled pose. This prevents excessive stretching when the head moves quickly.
float	mLinearDamping = 2.0f
	Linear damping coefficient for the simulated rods.
float	mAngularDamping = 2.0f
	Angular damping coefficient for the simulated rods.
float	mMaxLinearVelocity = 10.0f
	Maximum linear velocity of a vertex.
float	mMaxAngularVelocity = 50.0f
	Maximum angular velocity of a vertex.
Gradient	mGravityFactor { 0.1f, 1.0f, 0.2f, 0.8f }
	How much gravity affects the hair along its length, 0 = no gravity, 1 = full gravity. Can be used to reduce the effect of gravity.
float	mFriction = 0.2f
	Collision friction coefficient. Usually in the range [0, 1]. 0 = no friction.
float	mBendCompliance = 1.0e-7f
	Compliance for bend constraints: 1 / stiffness.
Float4	mBendComplianceMultiplier = { 1.0f, 100.0f, 100.0f, 1.0f }
	Multiplier for bend compliance at 0%, 33%, 66% and 100% of the strand length.
float	mStretchCompliance = 1.0e-8f
	Compliance for stretch constraints: 1 / stiffness.
float	mInertiaMultiplier = 10.0f
	Multiplier applied to the mass of a rod to calculate its inertia.
Gradient	mHairRadius = { 0.001f, 0.001f }
	Radius of the hair strand along its length, used for collision detection.
Gradient	mWorldTransformInfluence { 0.0f, 1.0f }
	How much rotating the head influences the hair, 0 = not at all, the hair will move with the head as if it had no inertia. 1 = hair stays in place as the head moves and is correctly simulated. This can be used to reduce the effect of turning the head towards the root of strands.
Gradient	mGridVelocityFactor { 0.05f, 0.01f }
	Every iteration this fraction of the grid velocity will be applied to the vertex velocity. Defined at cDefaultIterationsPerSecond, if this changes, the value will internally be adjusted to result in the same behavior.
float	mGridDensityForceFactor = 0.0f
	This factor will try to push the density of the hair towards the neutral density defined in the density grid. Note that can result in artifacts so defaults to 0.
Gradient	mGlobalPose { 0.01f, 0, 0.0f, 0.3f }
	Every iteration this fraction of the neutral pose will be applied to the vertex position. Defined at cDefaultIterationsPerSecond, if this changes, the value will internally be adjusted to result in the same behavior.
Gradient	mSkinGlobalPose { 1.0f, 0.0f, 0.0f, 0.1f }
	How much the global pose follows the skin of the scalp. 0 is not following, 1 is fully following.
float	mSimulationStrandsFraction = 0.1f
	Used by InitRenderAndSimulationStrands only. Indicates the fraction of strands that should be simulated.
float	mGravityPreloadFactor = 0.0f
	Note: Not fully functional yet! This controls how much of the gravity we will remove from the modeled pose when initializing. A value of 1 fully removes gravity and should result in no sagging when the simulation starts. A value of 0 doesn't remove gravity.

Detailed Description

The material determines the simulation parameters for a hair strand.

Member Function Documentation

GetBendCompliance()

float HairSettings::Material::GetBendCompliance ( float inStrandFraction ) const

inline

Calculate the bend compliance at a fraction along the strand.

GlobalPoseOnly()

bool HairSettings::Material::GlobalPoseOnly ( ) const

inline

If this material only needs running the global pose logic.

NeedsGrid()

bool HairSettings::Material::NeedsGrid ( ) const

inline

Returns if this material needs a density/velocity grid.

Member Data Documentation

mAngularDamping

float HairSettings::Material::mAngularDamping = 2.0f

Angular damping coefficient for the simulated rods.

mBendCompliance

float HairSettings::Material::mBendCompliance = 1.0e-7f

Compliance for bend constraints: 1 / stiffness.

mBendComplianceMultiplier

Float4 HairSettings::Material::mBendComplianceMultiplier = { 1.0f, 100.0f, 100.0f, 1.0f }

Multiplier for bend compliance at 0%, 33%, 66% and 100% of the strand length.

mEnableCollision

bool HairSettings::Material::mEnableCollision = true

Enable collision detection between hair strands and the environment.

mEnableLRA

bool HairSettings::Material::mEnableLRA = true

Enable Long Range Attachments to keep hair close to the modeled pose. This prevents excessive stretching when the head moves quickly.

mFriction

float HairSettings::Material::mFriction = 0.2f

Collision friction coefficient. Usually in the range [0, 1]. 0 = no friction.

mGlobalPose

Gradient HairSettings::Material::mGlobalPose { 0.01f, 0, 0.0f, 0.3f }

Every iteration this fraction of the neutral pose will be applied to the vertex position. Defined at cDefaultIterationsPerSecond, if this changes, the value will internally be adjusted to result in the same behavior.

mGravityFactor

Gradient HairSettings::Material::mGravityFactor { 0.1f, 1.0f, 0.2f, 0.8f }

How much gravity affects the hair along its length, 0 = no gravity, 1 = full gravity. Can be used to reduce the effect of gravity.

mGravityPreloadFactor

float HairSettings::Material::mGravityPreloadFactor = 0.0f

Note: Not fully functional yet! This controls how much of the gravity we will remove from the modeled pose when initializing. A value of 1 fully removes gravity and should result in no sagging when the simulation starts. A value of 0 doesn't remove gravity.

mGridDensityForceFactor

float HairSettings::Material::mGridDensityForceFactor = 0.0f

This factor will try to push the density of the hair towards the neutral density defined in the density grid. Note that can result in artifacts so defaults to 0.

mGridVelocityFactor

Gradient HairSettings::Material::mGridVelocityFactor { 0.05f, 0.01f }

Every iteration this fraction of the grid velocity will be applied to the vertex velocity. Defined at cDefaultIterationsPerSecond, if this changes, the value will internally be adjusted to result in the same behavior.

mHairRadius

Gradient HairSettings::Material::mHairRadius = { 0.001f, 0.001f }

Radius of the hair strand along its length, used for collision detection.

mInertiaMultiplier

float HairSettings::Material::mInertiaMultiplier = 10.0f

Multiplier applied to the mass of a rod to calculate its inertia.

mLinearDamping

float HairSettings::Material::mLinearDamping = 2.0f

Linear damping coefficient for the simulated rods.

mMaxAngularVelocity

float HairSettings::Material::mMaxAngularVelocity = 50.0f

Maximum angular velocity of a vertex.

mMaxLinearVelocity

float HairSettings::Material::mMaxLinearVelocity = 10.0f

Maximum linear velocity of a vertex.

mSimulationStrandsFraction

float HairSettings::Material::mSimulationStrandsFraction = 0.1f

Used by InitRenderAndSimulationStrands only. Indicates the fraction of strands that should be simulated.

mSkinGlobalPose

Gradient HairSettings::Material::mSkinGlobalPose { 1.0f, 0.0f, 0.0f, 0.1f }

How much the global pose follows the skin of the scalp. 0 is not following, 1 is fully following.

mStretchCompliance

float HairSettings::Material::mStretchCompliance = 1.0e-8f

Compliance for stretch constraints: 1 / stiffness.

mWorldTransformInfluence

Gradient HairSettings::Material::mWorldTransformInfluence { 0.0f, 1.0f }

How much rotating the head influences the hair, 0 = not at all, the hair will move with the head as if it had no inertia. 1 = hair stays in place as the head moves and is correctly simulated. This can be used to reduce the effect of turning the head towards the root of strands.

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The documentation for this struct was generated from the following file:

• Jolt/Physics/Hair/HairSettings.h