PT LIGHT

Summary

A PT LIGHT is a glowing surface that lights the scene and casts soft shadows. Pick its shape with Type, or wire in any POP to use as the shape, and place it with the Xform page. It shines from both sides.

Emit sets its brightness and Color its colour; a Color Texture lets it shine in the colours of an image. With Normalize by Area on, resizing the light changes the softness of its shadows but not its total light. See Lights and environment.

The Attributes page is shared by all PT MATs and PT LIGHTs in a project: changing it on one changes it on all.

Inputs

• Input 0: Shape - Optional. Any POP, used as the shape of the light instead of the built-in Type.

Outputs

• Output 0: Light - The light's geometry, as the Pathtracer reads it.

Light page

Type Type - The shape of the light. It shines from both sides. Menu · default Rectangle

• Rectangle - A 2 × 2 square facing along Z. Scale it on the Xform page.
• Circle - A disc with a diameter of 2, facing along Z.
• Ring - A thin ring with a diameter of 2, facing along Z.
• Point - A tiny sphere that behaves like a point light, with hard shadows.

Color Colorr Colorg Colorb - The colour of the light. Colour × 3 · default 1

Emit Emit - How bright the light is. Float · default 10

Render as Light Source Renderaslightsource - Shows the light's surface to the camera. Off, the light still lights the scene and shows in reflections, but the camera sees through it. Toggle · default On

Color Texture Colortexture - An image on the light's surface, multiplied with Color, so the light shines in its colours, like a screen or a window. TOP

Normal Normal - Which normals the light's shape gets. Smooth normals suit round shapes, flat ones flat and faceted shapes. Menu · default Vertex

• Point - Point normals (smooth).
• Primitive - Primitive normals (flat).
• Vertex - Vertex normals.

Texture Coordinates Texture - Which texture coordinates the built-in shape gets, for the Color Texture. Menu · default Vertex

• None - None.
• Point - Point texture coordinates.
• Vertex - Vertex texture coordinates.

Emit Emitattr - Where the emission comes from, as for Color, from an Emit attribute. Menu · default No Attribute

Normalize by Area Normalizebyarea - Divides the emission by the object's surface area, so its total light stays the same when you make it bigger or smaller. Turn it off to make Emit the brightness of the surface itself, so that larger objects give more light. Toggle · default On

Xform page

Transform Order Xord - The order in which scale, rotation and translation are applied. Menu · default Scale Rotate Translate

Rotate Order Rord - The order in which the rotations around X, Y and Z are applied. Menu · default Rx Ry Rz

Translate Tx Ty Tz - Moves the object. Float × 3 · default 0, 0, 10

Rotate Rx Ry Rz - Rotates the object, in degrees. Float × 3 · default 0

Scale Sx Sy Sz - Scales the object along each axis. Float × 3 · default 1

Pivot Px Py Pz - The point that the object rotates and scales around. Float × 3 · default 0

Uniform Scale Scale - Scales the object evenly in all directions. Float · default 1

Parent Transform Source Parentxformsrc - Where the object's starting position comes from. Menu · default From Parent Object (Hierarchy)

• From Parent Object (Hierarchy) - Its parent in the network, as with any Geometry COMP.
• Specify Parent Object - The object named in Parent Object.
• World Origin - The world origin, ignoring any parent.

Parent Object Parentobject - The object to follow when Parent Transform Source is set to Specify Parent Object. COMP

Look At Lookat - Turns the object to face another object, such as a Camera or a Null COMP. COMP

Forward Direction Forwarddir - Which axis of the object points at the Look At object. Menu · default -Z

Look At Up Vector Lookup - How the object is turned around the looking direction. Use the up vector unless the object you look at passes straight above or below this one. Menu · default Use Up Vector

Path OP Pathop - A curve to move the object along. Position sets where on the curve it is. OP

Roll Roll - Turns the object around its looking or path direction, in degrees. Float · default 0

Position Pos - Where on the Path OP the object is, from 0 (the start) to 1 (the end). Float · default 0 · min 0

Orient along Path Pathorient - Turns the object to point along the path. Toggle · default On

Orient Up Vector Upx Upy Upz - The direction the object's top points to while it follows a path. Float × 3 · default 0, 1, 0

Auto-Bank Factor Bank - Leans the object into the path's curves. 0 turns this off. Float · default 1

Pre-Xform page

Apply Pre-Transform Pxform - Applies the Pre-Xform page. Its transform comes before the Xform page's, like a parent's would. Toggle · default Off

Transform Order Pxord - The order in which the pre-transform's scale, rotation and translation are applied. Menu · default Scale Rotate Translate

Rotate Order Prord - The order of the pre-transform's rotations around X, Y and Z. Menu · default Rx Ry Rz

Translate Ptx Pty Ptz - Moves the object before the main transform. Float × 3 · default 0

Rotate Prx Pry Prz - Rotates the object before the main transform, in degrees. Float × 3 · default 0

Scale Psx Psy Psz - Scales the object before the main transform. Float × 3 · default 1

Pivot Ppx Ppy Ppz - The point that the pre-transform rotates and scales around. Float × 3 · default 0

Uniform Scale Pscale - Scales the object evenly before the main transform. Float · default 1

Reset Transform Preset - Resets the Pre-Xform page to no transform. Pulse

Commit to Main Transform Pcommit - Moves the pre-transform onto the Xform page and resets the Pre-Xform page. Pulse

Xform Matrix/CHOP/DAT Xformmatrixop - Transforms the object by a 4×4 matrix from a CHOP, DAT or matrix, applied before the pre-transform. CHOP

Render page

Render Render - Includes the light in the render. Off, the Pathtracer skips it. Toggle · default On

Attributes page

Color Colorattr - Where the colour comes from. None uses the Color parameter for the whole surface. Point, Primitive or Vertex read a Color attribute of that kind from the geometry, so the colour can change across the surface; where the geometry has none, the material's colour is written into it. Menu · default No Attribute

• No Attribute - The material's parameter, the same everywhere.
• Point - A point attribute of the same name.
• Primitive - A primitive attribute of the same name.
• Vertex - A vertex attribute of the same name.

Metallic Metallicattr - Where the metallic value comes from, as for Color, from a Metallic attribute. Menu · default No Attribute

Roughness Roughnessattr - Where the roughness comes from, as for Color, from a Roughness attribute. Menu · default No Attribute

IOR Iorattr - Where the index of refraction comes from, as for Color, from an Ior attribute. Menu · default No Attribute

Clear Coat Clearcoatattr - Where the clear coat amount comes from, as for Color, from a Clearcoat attribute. Menu · default No Attribute

Tint Clearcoattintattr - Where the clear coat tint comes from, as for Color, from a Clearcoattint attribute. Menu · default No Attribute

Transparency Transparencyattr - Where the transparency comes from, as for Color, from a Transparency attribute. Menu · default No Attribute

Absorption Absorptionattr - Where the absorption colour comes from, as for Color, from an Absorption attribute. Menu · default No Attribute

Dispersion Dispersionattr - Where the dispersion comes from, as for Color, from a Dispersion attribute. Menu · default No Attribute

Override if Attribute Exists Overrideifexists - When the geometry already carries one of these attributes, replace its values with the material's (on), or keep the geometry's own (off). Toggle · default On

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