RectLight

An intrinsic light that emits light from one side of a rectangle. The rectangle is centered in the XY plane and emits light along the -Z axis. The rectangle is 1 unit in length in the X and Y axis.

Use RectLights to illuminate objects, simulating soft boxes used in photography, linear lights, fluorescent lights, and light panels.

The following simple example has a RectLight positioned near a Sphere and Cube, with a width/height of 5x5, and using a colored checkerboard texture as a color map (with additional adjustments to light shaping cone angle and focus to limit the light spread).

#usda 1.0
(
    upAxis = "Y"
)

def Scope "Lights"
{
    def RectLight "Light1"
    {
        float inputs:width = 5
        float inputs:height = 5
        asset inputs:texture:file = @checkerboard.png@

        color3f inputs:color = (1, 1, 1)
        float inputs:intensity = 5.0
        float3 xformOp:rotateXYZ = (0, 90, 0)
        double3 xformOp:translate = (3.5, 0, -1)
        uniform token[] xformOpOrder = ["xformOp:translate", "xformOp:rotateXYZ"]        
    }
}

def Xform "TestGeom"
{
    def Sphere "Sphere1"
    {
        token purpose = "render"
        color3f[] primvars:displayColor = [(1, 1, 1)] (
            interpolation = "constant"
        )    
        double3 xformOp:translate = (0, 0, -2)
        uniform token[] xformOpOrder = ["xformOp:translate"]          
    }

    def Cube "Cube"
    {
        token purpose = "render"
        color3f[] primvars:displayColor = [(1, 1, 1)] (
            interpolation = "constant"
        )    
        double size = 8
        double3 xformOp:translate = (0, 0, -8)
        uniform token[] xformOpOrder = ["xformOp:translate"]          
    }
}

Example RenderMan output for this layer:

Properties

inputs:height

USD type: float

Fallback value: 1.0

The height of the rectangle in the local Y axis.

inputs:texture:file

USD type: asset

A color texture set on the rectangle that can act as a color map for the emitted light. In the default position, a texture file’s min coordinates should be at (+X, +Y) and max coordinates at (-X, -Y).

inputs:width

USD type: float

Fallback value: 1.0

The width of the rectangle in the local X axis.

light:shaderId

USD type: token

Fallback value: RectLight

The shader ID for a RectLight. USD will also register a Sdr shader node with a “RectLight” identifier and the source type “USD” to correspond to the light’s inputs

Inherited Properties (Boundable)

extent

USD type: float3[]

Inherited Properties (Xformable)

xformOpOrder

USD type: token[]

Inherited Properties (Imageable)

proxyPrim

USD type: rel (relationship)

purpose

USD type: token

Fallback value: default

visibility

USD type: token

Fallback value: inherited