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java.lang.Objectde.grogra.persistence.ShareableBase
de.grogra.imp3d.objects.LightBase
de.grogra.imp3d.objects.AmbientLight
public class AmbientLight
This class implements an ambient light.
Nested Class Summary | |
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static class |
AmbientLight.Type
|
Field Summary | |
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static AmbientLight.Type |
$TYPE
|
Fields inherited from class de.grogra.imp3d.objects.LightBase |
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color$FIELD, shadowless$FIELD |
Fields inherited from interface de.grogra.ray.physics.Light |
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AMBIENT, AREA, DIRECTIONAL, NO_LIGHT, POINT, SKY |
Fields inherited from interface de.grogra.ray.physics.Scattering |
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DELTA_FACTOR, IS_NON_OPAQUE, MIN_UNUSED_FLAG, NEEDS_NORMAL, NEEDS_POINT, NEEDS_TANGENTS, NEEDS_TRANSFORMATION, NEEDS_UV, RANDOM_RAYS_GENERATE_ORIGINS |
Constructor Summary | |
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AmbientLight()
|
Method Summary | |
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void |
accept(LightVisitor visitor)
|
float |
computeBSDF(Environment env,
Vector3f in,
Spectrum specIn,
Vector3f out,
boolean adjoint,
Spectrum bsdf)
Evaluates bidirectional scattering distribution function for given input. |
double |
computeExitance(Environment env,
Spectrum exitance)
Evaluates the exitance function for given input. |
protected void |
draw(Tuple3f color,
RenderState rs)
|
void |
generateRandomOrigins(Environment env,
RayList out,
java.util.Random rnd)
Pseudorandomly generates, for the given input, a set of origins for this emitter. |
void |
generateRandomRays(Environment env,
Vector3f out,
Spectrum specOut,
RayList rays,
boolean adjoint,
java.util.Random rnd)
Pseudorandomly generates, for the given input, a set of scattered rays. |
int |
getLightType()
Determines the type of light source which is represented by this light. |
ManageableType |
getManageableType()
|
double |
getTotalPower(Environment env)
Computes the total power of this light source which is emitted to the region defined by env.bounds . |
Methods inherited from class de.grogra.imp3d.objects.LightBase |
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completeRay, getAverageColor, getColor, getFlags, isIgnoredWhenHit, isShadowless, setShadowless |
Methods inherited from class de.grogra.persistence.ShareableBase |
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addReference, appendReferencesTo, fieldModified, getProvider, getStamp, initProvider, manageableReadResolve, manageableWriteReplace, removeReference |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final AmbientLight.Type $TYPE
Constructor Detail |
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public AmbientLight()
Method Detail |
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public void accept(LightVisitor visitor)
public float computeBSDF(Environment env, Vector3f in, Spectrum specIn, Vector3f out, boolean adjoint, Spectrum bsdf)
Scattering
The computed spectrum is an integral over the spectrum of the following product:
env.point
,
ωi the (negated) direction of the incoming light ray,
νi the frequency where the incoming ray is sampled,
ωo the direction of the outgoing light ray,
νo the frequency where the outgoing ray is sampled,
and θ the angle between the surface normal and out
.
If adjoint
is false
, in
and
out
describe true light rays from light sources to sensors.
In this case, ωi = in
,
ωo = out
, and the integral is
bsdf
(ν) = |cos θ| ∫ BSDF(in
, νi;
out
, ν) specIn
(νi) dνi
adjoint
is true
. in
and
out
then describe importance rays (inverse light rays
from sensors to light sources). In this case,
ωi = out
,
ωo = in
, and the integral is
bsdf
(ν) = |cos θ| ∫
BSDF(out
, ν;
in
, νo) specIn
(νo) dνo
If this Scattering
instance is in fact a
Light
source, adjoint
is false
,
and the BSDF is defined as BSDF(in
, μ; ω, ν)
= L1(ω, ν) δ(μ - ν),
i.e., the directional distribution
of the emitted radiance at env.point
, see Emitter
.
In this case, in
is not used.
If this Scattering
instance is in fact a
Sensor
, adjoint
is true
,
and the BSDF is defined as BSDF(ω, ν; in
, μ)
= W1(ω, ν) δ(μ - ν),
i.e., the directional distribution
of the emitted importance at env.point
, see Emitter
.
In this case, in
is not used.
The computation should be physically valid. This excludes, e.g., ambient or emissive light contributions.
The returned value
is the value of the probability density pω
that would be calculated by Scattering.generateRandomRays(de.grogra.ray.physics.Environment, javax.vecmath.Vector3f, de.grogra.ray.physics.Spectrum, de.grogra.ray.util.RayList, boolean, java.util.Random)
if
the ray happened to be one of the randomly generated rays.
env
- the environment for scatteringin
- the (negated) direction unit vector of the incoming ray
(i.e., pointing away from the surface)specIn
- the spectrum of the incoming rayout
- the direction unit vector of the outgoing ray
(i.e., pointing away from the surface)adjoint
- light ray or importance ray?bsdf
- the computed spectrum of the outgoing ray will be placed in here
public double computeExitance(Environment env, Spectrum exitance)
Emitter
env.point
in case of light sources, or the
corresponding function W0j(x, ν) in case
of sensors.
The returned value
is the value of the probability density px
that would be calculated by Emitter.generateRandomOrigins(de.grogra.ray.physics.Environment, de.grogra.ray.util.RayList, java.util.Random)
if
env.point
happened to be one of the randomly generated
origins.
env
- the environment for scatteringexitance
- the exitance values will be placed in here
protected void draw(Tuple3f color, RenderState rs)
draw
in class LightBase
public void generateRandomOrigins(Environment env, RayList out, java.util.Random rnd)
Emitter
At first, we consider the case where the emitter is in fact a light source. Let L(x, ω, ν) be the emitted spectral radiance for the frequency ν at the light's surface point x in direction ω. The radiant exitance (emitted spectral power per area) at x is defined as
rays.size
). Then
for a function f(x, ν) which is to be
integrated over the light surface, the sum
Now if the emitter is a sensor, let W(x, ω, ν) be the emitted spectral importance for frequency ν at the sensors's surface point x in direction ω. The quantities W0(x, ν) and W1(x, ω, ν) are defined similarly to the case of light sources:
Let px be the probability density used for the ray
origin, then the field originDensity
is set to px(oi) for each ray.
For emitters which are concentrated at a single point
(e.g., point lights) px is not
a regular function, the value originDensity
will
be set to a multiple of Scattering.DELTA_FACTOR
.
The ray properties which are not mentioned in the given formulas are neither used nor modified. These are the direction and its density.
env
- the environmentout
- the outgoing rays to be generatedrnd
- pseudorandom generatorpublic void generateRandomRays(Environment env, Vector3f out, Spectrum specOut, RayList rays, boolean adjoint, java.util.Random rnd)
Scattering
adjoint
is false
,
out
= ωo describes
the direction of an outgoing light ray.
In this case, the integration is with respect to ωi.
Let g(ω, ν; out
, μ)
= BSDF(ω, ν; out
, μ)
adjoint
is true
. In this case,
out
= ωi describes
the direction of an outgoing importance ray (an inverse light ray).
Now the integration is with respect to ωo.
Let g(ω, ν; out
, μ)
= BSDF(out
, μ; ω, ν)
rays.size
). Then, for every
frequency ν the sum
out
, μ)
specOut
(μ) dμ dω
If this Scattering
instance is in fact a
Light
source, adjoint
is true
,
and the BSDF is defined as BSDF(out
, μ; ω, ν)
= L1(ω, ν) δ(μ - ν),
i.e., the directional distribution
of the emitted radiance at env.point
, see Emitter
.
In this case, out
is not used.
If this Scattering
instance is in fact a
Sensor
, adjoint
is false
,
and the BSDF is defined as BSDF(ω, ν; out
, μ)
= W1(ω, ν) δ(μ - ν),
i.e., the directional distribution
of the emitted importance at env.point
, see Emitter
.
In this case, out
is not used.
Let pω be the probability density
used for the ray direction (measured with respect to
solid angle ω),
then the field directionDensity
of the ray i
is set to pω(di).
For ideal specular reflection or transmission, or for directional
lights or sensors, pω is not
a regular function, the value directionDensity
will
be set to a multiple of Scattering.DELTA_FACTOR
.
The ray properties which are not mentioned in the given formulas are neither used nor modified. These are the origin and its density.
env
- the environment for scatteringout
- the direction unit vector of the outgoing ray
(i.e., pointing away from the surface)specOut
- the spectrum of the outgoing rayrays
- the rays to be generatedadjoint
- represents out
a light ray or an importance ray?rnd
- pseudorandom generatorScattering.computeBSDF(de.grogra.ray.physics.Environment, javax.vecmath.Vector3f, de.grogra.ray.physics.Spectrum, javax.vecmath.Vector3f, boolean, de.grogra.ray.physics.Spectrum)
public int getLightType()
Light
Light.NO_LIGHT
, Light.POINT
, Light.AREA
,
Light.DIRECTIONAL
, Light.SKY
, Light.AMBIENT
.public ManageableType getManageableType()
public double getTotalPower(Environment env)
Light
env.bounds
. Note that the computed
value is not necessarily exact: It should be used just as a hint, e.g.,
when one of a set of lights has to be chosen randomly on the basis of
their relative power.
env
- environment which defines the bounds of the scene
env.bounds
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