# PointLight

PointLight[col,pt]

is a three-dimensional graphics directive that specifies the point light of color col at position pt to use in coloring 3D surfaces.

PointLight[col,pt,att]

uses the point light with geometric attenuation att.

# Details

• PointLight is also known as spherical point light.
• PointLight is typically used to illuminate certain sections of an object by casting light rays that spread evenly in all directions.
• PointLight[col,pt] yields a light that emanates from the point pt but does not attenuate with distance.
• Colors of light sources col can be defined by RGBColor, Hue or any other color specification.
• The setting for PointLight affects only colors associated with diffuse and specular reflection on a 3D surface.
• Light sources with color specifications of the form {dcol,Specularity[scol]} are effectively taken to have colors dcol for purposes of diffuse reflection, and scol for purposes of specular reflection.
• Diffuse reflection is taken to follow Lambert's law, with light effectively scattered equally in all directions from a surface.
• Specular reflection effectively takes light to be scattered only close to the mirrorreflection direction, as specified in the notes for Specularity.
• Light source positions pt can be specified as follows:
•  {x,y,z} explicit coordinates that move with the graphic Scaled[{x,y,z}] scaled coordinates that move with the graphic ImageScaled[{x,y,z}] coordinates fixed relative to the final displayed image
• In ImageScaled[{x,y,z}], the and run from 0 to 1 across the width and height of the bounding box of the final displayed image. The coordinate runs orthogonal to the plane of the display, and is 0 at the back of the 3D region and 1 at the front.
• Coordinates specified in Scaled and ImageScaled will often not be between 0 and 1.
• PointLight[col,pt,{a,b,c}] yields a light that attenuates like with distance .

# Examples

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## Basic Examples(3)

Point light on surfaces:

Style a surface in a plot:

A point light from the top of the specular surface:

## Scope(7)

### Lighting Specification(4)

Specify a spherical point light source by a color and a position:

Point lights with different colors:

Point lights at various positions:

Point lights on specular surfaces:

### Lighting Positions(2)

Specify the light source position in the graphics coordinate system by default:

The light source moves with the graphic when the viewpoint changes:

Specify the light position by a fraction of the graphics coordinates using Scaled:

The light source moves with the graphic when the viewpoint changes:

### Lighting Attenuation(1)

By default, point lights are not affected by the distance from an object:

Specify a point light that attenuates with respect to the distance:

Specify a point light that attenuates by the square of the distance:

## Generalizations & Extensions(2)

Specify lighting for each object:

Specify lighting within the graphics:

## Applications(3)

Set up four white spheres on a plane:

Point light:

Different light instruments at the corner points:

Build a scene with multiple objects and light sources:

Animate the spotlights:

## Properties & Relations(6)

Surface color and lighting interact with each other:

Diffuse object and lighting colors can be exchanged and produce the same effect:

Specular object and lighting colors can be exchanged and produce the same effect:

Specularity gives mirror-like reflection:

The final color is a linear combination of all the surface colors as well as lighting:

Point light yields rays toward all the directions from the position:

## Possible Issues(2)

The default light scheme uses several colored light sources:

Set Lighting to None to turn off the default lights:

Flat surfaces may show little or no reflection:

## Neat Examples(1)

A simple light show:

Wolfram Research (2021), PointLight, Wolfram Language function, https://reference.wolfram.com/language/ref/PointLight.html.

#### Text

Wolfram Research (2021), PointLight, Wolfram Language function, https://reference.wolfram.com/language/ref/PointLight.html.

#### CMS

Wolfram Language. 2021. "PointLight." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/PointLight.html.

#### APA

Wolfram Language. (2021). PointLight. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/PointLight.html

#### BibTeX

@misc{reference.wolfram_2024_pointlight, author="Wolfram Research", title="{PointLight}", year="2021", howpublished="\url{https://reference.wolfram.com/language/ref/PointLight.html}", note=[Accessed: 13-August-2024 ]}

#### BibLaTeX

@online{reference.wolfram_2024_pointlight, organization={Wolfram Research}, title={PointLight}, year={2021}, url={https://reference.wolfram.com/language/ref/PointLight.html}, note=[Accessed: 13-August-2024 ]}