API Docs

Class: SkyPatchCache

PD.SkyDome~ SkyPatchCache

new SkyPatchCache(shading, solar, jitter)

Internal class to generate a cached array of illuminance/radiance values for fast random-access or sequentially iterating through sky patches in the current sky.

Parameters:
Name Type Description
shading PD.SkyDome

The parent shading object to use.
solar PD.SolarPosition

The solar position calculation object to use.
jitter boolean

Whether or not to pseudo-randomly perturb each patch's center.

Members

:number

diffuseHorizontal

The instantaneous direct radiation/illuminance from the Sun.

Type
  • number
:number

directBeam

The instantaneous diffuse horizontal radiation/illuminance from the sky.

Type
  • number
:SkyPatchIterator

iterator

The object used for iterating through sky dome patches.

Type
  • SkyPatchIterator
:number

patchCount

The total number of sky patches in the sky dome.

Type
  • number
:number

patchTotal

The total horizontal illuminance from the entire sky dome.

Type
  • number
:Array

patches

The array of cached sky patch information.

This is a simple object with vector and result properties.

Type
  • Array
:PD.Utils.VectorObject

sunVector

The 3D vector array storing the direction towards the Sun.

Type
  • PD.Utils.VectorObject

Methods

createFlatArray( [array])

Creates a flat array of sky segment data.

The resulting array is a Float32Array with an initial header of 7 entries followed by 7 entries per sky patch. These are described in the table below.

| INDEX | DESCRIPTION | |+-----+|-------------| | 0 | Number of sky patches in array. | | 1 | The stored total available. | | 2 | The instantaneous direct radiation/illuminance from the Sun. | | 3 | The instantaneous diffuse horizontal radiation/illuminance from the sky. | | 4 | X-axis component of vector to Sun. | | 5 | Y-axis component of vector to Sun. | | 6 | Z-axis component of vector to Sun. | |+-----+|-------------| | #0 | X-axis component of vector to patch center. | | #1 | Y-axis component of vector to patch center. | | #2 | Z-axis component of vector to patch center. | | #3 | Azimuth of patch center, in degrees. | | #4 | Altitude of patch center, in degrees. | | #5 | The cosine of the sky zenith angle. | | #6 | Unadjusted contribution of patch. |

NOTE: This method returns raw sky patch contributions which are suitable for spherical integration. To calculate surface incidence, you must multiply each segment value by the cosine of the incidence angle. For incidence on a horizontal surface, the cosine of the zenith angle is already calculated and provided in the array, so simply multiply by the 5th entry of each patch.

Parameters:
Name Type Argument Description
array Array <optional>

An optional array to reuse if the same size.
Returns:

Returns a flat array of sky segment data.

Type
Array

initialise()

Resets and initialises the iterative calculation.

You must call this before iterating over values.

jitter( [state])

Get/set whether or not to pseudo-randomly perturb each patch's center.

Parameters:
Name Type Argument Description
state boolean <optional>

An optional new state for pseudo-randomly perturbing each patch's center.
Returns:

Returns whether or not each each patch's center is pseudo-randomly perturbed.

Type
boolean

perezSky()

Retrieve the PD.PerezSky object used to generate sky distributions.

Returns:

Returns the Perez Sky object used to generate sky distributions.

Type
PD.PerezSky

shading( [new_shading])

Get/set the shading object to use.

Parameters:
Name Type Argument Description
new_shading PD.SkyDome <optional>

An optional new shading object to use.
Returns:

Returns the shading object being used.

Type
PD.SkyDome

solar( [new_solar])

Get/set the solar position calculation object to use.

Parameters:
Name Type Argument Description
new_solar PD.SolarPosition <optional>

An optional new solar position calculation object to use.
Returns:

Returns the solar position calculation object being used.

Type
PD.SolarPosition

update()

Updates the cache with sky patch data.

NOTE: This method returns raw sky patch contributions which are suitable for spherical integration. To calculate surface incidence, you must multiple each segment value by the cosine of the incidence angle. For incidence on a horizontal surface, the cosine of the zenith angle is already calculated and provided in the array, so simply multiply by iterator.cosZen.