Experimental:Lookup Channel POP

Summary

The Lookup Channel POP in its simplest form takes an attribute (the Lookup Attribute) with values in the 0-1 range and for each point, uses the attribute value as an index into the channels of a CHOP, pulling one interpolated value for each channel, and placing those values into POP attributes.

If the index is 0, it pulls values from the first sample of the CHOP, and if the index is 1 it pulls from the last sample of the CHOP. If the Lookup Index Units menu is set to Sample Index, the lookup index can be expressed as sample number, going from 0 to number_of_samples-1.

If the index is out of range, the Extend Left and Right menus determine what to do to the index before doing the lookup, such as holding it at 0 or 1, or cycling the value between 0 and 1.

Sequential blocks determine what to do with each of the channel values when they are retrieved - you can re-range the value before putting it in the specified output attribute.

See also Lookup Texture POP, Curve POP (Lookup page), Lookup Attribute POP

lookupchannelPOP_Class

Parameters - Lookup Page

Attribute Class attrclass - ⊞ -

• Point point -

• Vertex vertex -

• Primitive primitive -

Group group -

CHOP chop -

Lookup Attribute(s) lookupattr -

Lookup Attr is Sample Index sampleindex -

Cyclic Index cyclic -

Interpolate interpolate -

Extend Left and Right extendleft - ⊞ -

• Hold hold -

• Slope slope -

• Cycle cycle -

• Mirror mirror -

Extend Right extendright - ⊞ -

• Hold hold -

• Slope slope -

• Cycle cycle -

• Mirror mirror -

Lookup lookup -

Channel Scope lookup0chanscope -

From Low lookup0fromlow -

From High lookup0fromhigh -

To Low lookup0tolow -

To High lookup0tohigh -

Output Attribute Scope lookup0outputattrscope - ⊞ -

• P P -

• N N -

• Color Color -

• Color.i012 Color.i012 -

• Tex Tex -

• PointScale PointScale -

• LineWidth LineWidth -

Override Automatic Attribute lookup0overrideautoattr -

New Attribute Type lookup0newattrtype - ⊞ -

• float float -

• double double -

• int int -

• uint uint -

• dir dir -

• dbl dir ddir -

New Attribute Number of Components lookup0attrnumcomps - ⊞ -

• 1 1 -

• 2 2 -

• 3 3 -

• 4 4 -

New Attribute Default Value lookup0newattrdefaultval - ⊞ -

• New Attribute Default Value lookup0newattrdefaultval1 -

• New Attribute Default Value lookup0newattrdefaultval2 -

• New Attribute Default Value lookup0newattrdefaultval3 -

• New Attribute Default Value lookup0newattrdefaultval4 -

Parameters - Common Page

Bypass bypass -

Delete Input Attributes delinputattrs -

Parameter Color Space parmcolorspace - ⊞ - Controls how all color parameters on this node are interpreted. The color values as treated as being in the selected color space, and are converted to the Working Color Space before they are used as part of the node's operation. Note that this does not change the color space of the node itself, as that is always in the Working Color Space.

• sRGB srgb - sRGB color space, with sRGB transfer function. Considered an SDR color space with respect to Reference White.

• sRGB - Linear srgblinear - sRGB color space, with linear transfer function. Considered an SDR color space with respect to Reference White.

• Rec.601 (NTSC) rec601ntsc - Rec.601 with NTSC primaries color space, with Rec.601 transfer function. Considered an SDR color space with respect to Reference White.

• Rec.709 rec709 - Rec.709 color space, with Rec.709 (same as Rec.2020) transfer function. Considered an SDR color space with respect to Reference White.

• Rec.2020 rec2020 - Rec.2020 color space, with Rec.2020 (same as Rec.709) transfer function. Considered an HDR color space with respect to Reference White.

• DCI-P3 dcip3 - DCI-P3 color space, with D65 white point and 2.6 gamma transfer function. Considered an HDR color space with respect to Reference White.

• DCI-P3 (D60) dcip3d60 - DCI-P3 "D60 sim" color space, with D60 white point, and 2.6 gamma transfer function. Considered an HDR color space with respect to Reference White.

• Display-P3 (D65) displayp3d65 - Display-P3 color space, with D65 white point, and sRGB gamma transfer function. Considered an HDR color space with respect to Reference White.

• ACES2065-1 aces2065-1 - ACES 2065-1 (also known as ACES AP0) color space, with a linear gamma transfer function. Considered an HDR color space with respect to Reference White.

• ACEScg acescg - ACEScg (also known as ACES AP1) color space, with a linear gamma transfer function. Considered an HDR color space with respect to Reference White.

• Passthrough passthrough - When selected, the color values will be used as-is in the operation, without any modification or attempt to convert them into the Working Color Space.

Parameter Reference White parmreferencewhite - ⊞ - When converting a parameter color value to the Working Color Space, this controls how it should be treated with respect to Reference White. If the Working Color Space is the same Reference White, then no adjustment is done. If they are different, then the Reference White level (brightness) of this color will be adjusted to the range expected by the Working Color Space. For example if the project is set to have a SDR Reference White of 120 nits, and the HDR Reference White is 80 nits, then a color of (1, 1, 1), which is 120 nits in the SDR color space, will be converted to be (1.5, 1.5, 1.5), which is 120 nits still in the HDR Working Color Space.

• Default For Color Space default - Will use either the SDR or the HDR Reference White, based on the color space selected.

• Standard (SDR) sdr - Will treat the Parameter Color Space as SDR for it's reference white value.

• High (HDR) hdr - Will treat the Parameter Color Space as HDR for it's reference white value.

Operator Inputs

• Input 0: -

Info CHOP Channels

Extra Information for the Lookup Channel POP can be accessed via an Info CHOP.

Common Operator Info Channels

• total_cooks - Number of times the operator has cooked since the process started.

• cook_time - Duration of the last cook in milliseconds.

• cook_frame - Frame number when this operator was last cooked relative to the component timeline.

• cook_abs_frame - Frame number when this operator was last cooked relative to the absolute time.

• cook_start_time - Time in milliseconds at which the operator started cooking in the frame it was cooked.

• cook_end_time - Time in milliseconds at which the operator finished cooking in the frame it was cooked.

• cooked_this_frame - 1 if operator was cooked this frame.

• warnings - Number of warnings in this operator if any.

• errors - Number of errors in this operator if any.

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An Operator Family which operate on Channels (a sequence of numbers (Samples)) which are used for animation, audio, mathematics, simulation, logic, UI construction, and data streamed from/to devices and protocols.

Each SOP has a list of Points. Each point has an XYZ 3D position value plus other optional attributes. Each polygon Primitive is defined by a vertex list, which is list of point numbers.

A sequence of vertices form a Polygon in a SOP. Each vertex is an integer index into the Point List, and each Point holds an XYZ position and attributes like Normals and Texture Coordinates.

A surface type in SOPs that includes polygon, curve (NURBS and Bezier), patch (NURBS and Bezier) and other basic shapes like sphere, tube and metaball. Points and Primitives are part of the Geometry Detail, which is a part of a SOP.

A parameter in most CHOPs that restricts which channels of that CHOP will be affected. Normally all channels of a CHOP are affected by the operator. TOPs have Channel Mask, a similar feature.

An operator whose Bypass flag is set does nothing: All data going into its first input appears at its output unaffected.

Information associated with SOP geometry. Points and primitives (polygons, NURBS, etc.) can have any number of attributes - position (P) is standard, and built-in optional attributes are normals (N), texture coordinates (uv), color (Cd), etc.

A Link. The grey dashed lines between nodes is a Reference or Link that indicates one operator is getting data from another operator from any Operator Family.

The grey dashed lines between nodes is a Reference (or Link). A Reference is (1) a Parameter Reference, a parameter in an OP that is a name or path to another operator, (2) a Node Reference, an expression in a parameter or DAT script that contains the name or path of another operator, (3) a DAT Cell Reference or (4) a CHOP Channel Reference.

A Link or Reference is a dashed line between nodes that represent other data flowing between nodes. Examples are CHOP Exports, node Paths in parameters, and expressions in parameters referencing CHOP channels, DAT tables and other nodes. In contrast is a Wire that connects nodes in the same Operator Family.

A parameter reference can be setup between any two parameters by putting an expression in one parameter that refers to another parameter. This creates a Link between the two parameters such that when one changes, the other will change automatically (known in other software as a "constraint").