LightShader Class Reference

Base class for LightShader plugins to describe emission of light. More...

#include <core/LightShader.h>

Inheritance diagram for LightShader:

[legend]List of all members.

Public Member Functions
virtual rgb	emittedRadiance (const HitRecord &rec, Context &context) const
virtual void	estimateRadiance (const HitRecord &rec, Context &context, Vector3 &w_in, double &distance, rgb &radiance) const
virtual rgb	estimateBGRadiance (const HitRecord &rec, const Vector3 &w_in, Context &context) const
virtual bool	sampleDirection (const HitRecord &rec, Context &context, Vector3 &w_in, double &pdf) const
virtual double	pdfDirection (const Vector3 &w_in, const HitRecord &rec, Context &context) const

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Detailed Description

Base class for LightShader plugins to describe emission of light.

The LightShader class describes the emission of light. This applies to area lights, singular light shaders (point lights, directional lights, etc) and background light.

When sampling light sources, the returned value of the pdf must be equivalent to calling pdfDirection with the the same inputs and the generated direction. Otherwise the mismatch will cause an invalid result.

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Member Function Documentation

virtual rgb LightShader::emittedRadiance (  const HitRecord &  rec, Context &  context )  const [inline, virtual]

Used for area lights. The area light's surface has been intersected, so the shader should return the emitted radiance at the hit point in the direction ray came from. Parameters: [in]  rec  HitRecord describing the hit point on the luminaire. [in]  context  Rendering Context containing the ray data. Returns: rgb value representing the emitted radiance. Reimplemented in DiffuseLightShader, and SpectralLight.

virtual void LightShader::estimateRadiance (  const HitRecord &  rec, Context &  context, Vector3 &  w_in, double &  distance, rgb &  radiance )  const [inline, virtual]

Estimate the radiance this light deposits towards a point in the scene. The light should not attempt an intersection with the scene to determine if an occlusion exists. Occlusion testing can be performed by the caller with the retured 'w_in' and 'distance'. Singular light sources, such as point lights, would only implement this function and allow the caller to test for occlusion. LightShaders intended for area lights may also implement this function as it may allow for importance sampling of luminaires based on estimated radiance. Parameters: [in]  rec  HitRecord for the point asking for a radiance estimate. [in]  context  The standard rendering context. [out]  w_in  The unit length vector to the light. [out]  distance  Distance from the shading point to the light. [out]  radiance  The radiance estimate. Reimplemented in ConstantEnvironment, CylindricalEnvironment, and UberLight.

virtual rgb LightShader::estimateBGRadiance (  const HitRecord &  rec, const Vector3 &  w_in, Context &  context )  const [inline, virtual]

Estimate the radiance this light produces along the ray given by the input direction and the hit point in rec. This function is intended for background environments and should be called for rays that leave the scene without intersecting any geometry. Parameters: [in]  rec  HitRecord for the point being lit. [in]  w_in  Unit length vector towards the light. [in]  context  The standard rendering context. Returns: rgb value representing the incident radiance. Reimplemented in ConstantEnvironment, and CylindricalEnvironment.

virtual bool LightShader::sampleDirection (  const HitRecord &  rec, Context &  context, Vector3 &  w_in, double &  pdf )  const [inline, virtual]

Attempt to generate a directional sample towards this light source. Parameters: [in]  rec  The HitRecord for the point being lit. [in]  context  The standard rendering context. [out]  w_in  Unit length vector pointing towards the light source. [out]  pdf  The value of the pdf for this vector. Returns: True if a sample was generated. Reimplemented in ConstantEnvironment, and CylindricalEnvironment.

virtual double LightShader::pdfDirection (  const Vector3 &  w_in, const HitRecord &  rec, Context &  context )  const [inline, virtual]

Evaluate the pdf of generating the sampled direction. Parameters: [in]  w_in  Unit length vector. [in]  rec  The HitRecord of the point being lit. [in]  context  The standard rendering context. Returns: Evaluation of the pdf for the direction. Reimplemented in ConstantEnvironment, and CylindricalEnvironment.

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

• LightShader.h

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