org.sunflow.core
Interface LightSource

All Superinterfaces:

RenderObject

All Known Implementing Classes:

CornellBox, DirectionalSpotlight, ImageBasedLight, PointLight, SphereLight, SunSkyLight, TriangleMeshLight

public interface LightSource
extends RenderObject

This interface is used to represent any light emitting primitive. It permits efficient sampling of direct illumination and photon shooting.

Method Summary

Instance	createInstance() Create an instance which represents the geometry of this light source.
int	getNumSamples() Get the maximum number of samples that can be taken from this light source.
void	getPhoton(double randX1, double randY1, double randX2, double randY2, Point3 p, Vector3 dir, Color power) Gets a photon to emit from this light source by setting each of the arguments.
float	getPower() Get the total power emitted by this light source.
void	getSamples(ShadingState state) Samples the light source to compute direct illumination.

Methods inherited from interface org.sunflow.core.RenderObject

update

Method Detail

getNumSamples

int getNumSamples()

Get the maximum number of samples that can be taken from this light source. This is currently only used for statistics reporting.

Returns:

maximum number of samples to be taken from this light source

getSamples

void getSamples(ShadingState state)

Samples the light source to compute direct illumination. Light samples can be created using the LightSample class and added to the current ShadingState. This method is responsible for the shooting of shadow rays which allows for non-physical lights that don't cast shadows. It is recommended that only a single shadow ray be shot if ShadingState.getDiffuseDepth() is greater than 0. This avoids an exponential number of shadow rays from being traced.

Parameters:

state - current state, including point to be shaded

See Also:

LightSample

getPhoton

void getPhoton(double randX1,
               double randY1,
               double randX2,
               double randY2,
               Point3 p,
               Vector3 dir,
               Color power)

Gets a photon to emit from this light source by setting each of the arguments. The two sampling parameters are points on the unit square that can be used to sample a position and/or direction for the emitted photon.

Parameters:

randX1 - sampling parameter

randY1 - sampling parameter

randX2 - sampling parameter

randY2 - sampling parameter

p - position to shoot the photon from

dir - direction to shoot the photon in

power - power of the photon

getPower

float getPower()

Get the total power emitted by this light source. Lights that have 0 power will not emit any photons.

Returns:

light source power

createInstance

Instance createInstance()

Create an instance which represents the geometry of this light source. This instance will be created just before and removed immediately after rendering. Non-area light sources can return null to indicate that no geometry needs to be created.

Returns:

an instance describing the light source