Curve POP

Summary

The Curve POP is used to generate a curve in XY (Z=0) that can be used as a lookup curve for a Lookup Attribute POP or elsewhere. It is a "function" in that the P(0) X-value steps forward uniformly from point to point, while the P(1) Y-value takes on different interpolated shapes. The curve it generates is also in an attribute Curve, which you can use instead of P(1) for clarity.

Like the S Curve CHOP, it defaults to an ease-in ease-out curve, but the Curve POP lets you add multiple segments (sequential blocks) that enable a greater range of curves. The curve can be made of several segments defined by Sequential Blocks of parameters, each with its own start and end values and Curve Type.

The Curve Type includes Constant, Linear, the Eases and Bezier.

The Alpha and Beta values affect the curve, where Alpha makes it more- or less-sloped, and Beta makes it more biased to the start or end of the segment. When Bezier is selected, Slope In and Slope Out affect the slopes at the end-points of the segment.

More generally, we treat the 2 axes as U and V. The curves can output as points-only, a linestrip, or as an RGBA color curves.

Because the U values can start and end at any value, you can normalize the curve so the U values (P(0)) are between 0 and 1.

The curve can be extended to double length and made symmetric using the Symmetric toggle.

The Lookup page lets you apply the curve as a lookup without first converting anything to points. This preerves maximum accuracy, and avoids interpolation problems when a lookup curve sharply steps from one value to another as may occur between two segments. In this case you attach an input POP where you want to modify one or more attributes with the curve. In this mode it behaves similar to the Lookup Attribute POP.

Tip: If you want specific points to exactly hit your U keyframe values, make sure your (Number of Points - 1) is divisible evenly by your U values.

curvePOP_Class

Parameters - Curve Page

Total Length totallength - Determines the number of points.

Output Curve outputcurve - ⊞ - Selects the type of primitive to output.

Points points -

Line Strips linestrip -

Color Strip colorstrip -

Normalize U normalizeu - Normalize all the U values so their range is 0 to 1.

Symmetric symmetric - Enable mirroring the curve segments.

Parameter Size parsize - ⊞ - Number of independent configurable parameter values.

1 1 -

2 2 -

3 3 -

4 4 -

Start U startu - Start U position for the first segment.

Segment seg - Start of Sequential Parameter Blocks for creating curve segments.

Curve Type seg0type - ⊞ - The interponation type of the curve between the start and end of the segment.

Constant constant -

Linear linear -

Ease In easein -

Ease Out easeout -

Ease In Ease Out easeinout -

Bezier bezier -

U seg0u - Sets the segments end U.

Specify Start Value seg0specstartval - When set, the segment has a start value, otherwise it is a continuation of the previous segment.

Start Value seg0startval - When set, the segment has a start value, otherwise it is a continuation of the previous segment.

End Value seg0endval - The value at the end of a curve segment.

Alpha seg0alpha - One paramter that affects the curve, usually a form of steepness.

Beta seg0beta - A second paramter that affects the curve, usually a form of bias to the start or end of a curve segment.

Slope in seg0slopein - Bezier slope factor for the incoming curve segment.

Slope Out seg0slopeout - Bezier slope factor for the outgoing curve segment.

Parameters - Lookup Page

Apply Lookup applylookup - The Lookup page lets you apply the curve as a lookup without first converting anything to points.

Lookup Index Attribute lookupindexattr - Attribute to use as the index for the lookup.

From Low High fromlow - ⊞ - Reranges the attribute value.

From Low High fromlow -

From High fromhigh - Reranges the index attribute value.

To Low High tolow - ⊞ - Reranges the input lookup attribute value.

To Low High tolow -

To High tohigh - Sets high value on the output range.

Extend Left and Right extendleft - ⊞ - What happens when the lookup samples outside of the range.

Hold hold -

Slope slope -

Cycle cycle -

Mirror mirror -

Extend Left and Right extendleft -

Extend Right extendright - What happens when the lookup samples the curves outside its U range.

Lookup lookup - Start of Sequential Parameter Blocks of lookups.

Multiply lookup0multiply - A multiplier that is applied to the lookup result.

Add lookup0add - A value you add to the result of a lookup.

Combine Operation lookup0combineop - ⊞ - After a value is retrieved doing the lookup, it can be added or multiplied with an attribute.

Set set -

Add add -

Multiply mult -

Minimum min -

Maximum max -

Output Attribute Scope lookup0outputattrscope - ⊞ - Name of attribute to output (can choose components of attribute), can choose from menu.

P P -

N N -

Color Color -

Color.rgb Color.rgb -

Tex Tex -

PointScale PointScale -

LineWidth LineWidth -

Override Automatic Attribute lookup0overrideautoattr - Whether to override the kind of attribute automatically created based on the POP input and parameters. Allows to specify manually the type and number of components of the new attribute.

Attribute Type lookup0attrtype - ⊞ - The lookup attribute type.

float float -

double double -

int int -

uint uint -

dir dir -

dbl dir ddir -

Components lookup0attrnumcomps - ⊞ - The number of components in the new custom attribute.

1 1 -

2 2 -

3 3 -

4 4 -

Default Value lookup0attrdefaultval - ⊞ - Default values of the output attribute components if they cannot be computed.

Default Value lookup0attrdefaultval0 -

Default Value lookup0attrdefaultval1 -

Default Value lookup0attrdefaultval2 -

Default Value lookup0attrdefaultval3 -

Extend Right extendright - ⊞ -

Hold hold -

Slope slope -

Cycle cycle -

Mirror mirror -

Parameters - Common Page

Bypass bypass - Pass through the first input to the output unchanged.

Free Extra GPU Memory freeextragpumem - Free memory that has accumulated when output memory has grown and shrunk.

Delete Input Attributes delinputattrs - Only output which attributes you specify in this POP - helps isolate attributes into a separate branch.

Operator Inputs

Input 0: -

Info CHOP Channels

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

Common POP Info Channels

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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