---
name: "plscmap1la"
section: "3plplot"
platform: "linux"
package: "plplot-doc"
version: "5.15.0+dfsg2-15"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/plscmap1la"
---

# plscmap1la(3plplot)

Set cmap1 colors and alpha transparency using a piece-wise linear relationship

## NAME

**plscmap1la** - Set cmap1 colors and alpha transparency using a piece-wise linear relationship

## SYNOPSIS

**plscmap1la**(*itype*, *npts*, *intensity*, *coord1*, *coord2*, *coord3*, *alpha*, *alt\_hue\_path*)

## DESCRIPTION

This is a variant of [**plscmap1l**(3plplot)](/plscmap1l/3plplot.md) that supports alpha channel transparency. It sets cmap1 colors using a piece-wise linear relationship between cmap1 intensity index (0.0-1.0) and position in HLS or RGB color space (see the PLplot documentation) with *alpha* transparency value (0.0-1.0). It may be called at any time.

Redacted form: **plscmap1la(itype, intensity, coord1, coord2, coord3, alpha, alt\_hue\_path)**

This function is used in example 30.

## ARGUMENTS

- *itype* (**PLBOOL**(3plplot), input)

  true: RGB, false: HLS.

- *npts* (**PLINT**(3plplot), input)

  number of control points.

- *intensity* (**PLFLT\_VECTOR**(3plplot), input)

  A vector containing the cmap1 intensity index (0.0-1.0) in ascending order for each control point.

- *coord1* (**PLFLT\_VECTOR**(3plplot), input)

  A vector containing the first coordinate (H or R) for each control point.

- *coord2* (**PLFLT\_VECTOR**(3plplot), input)

  A vector containing the second coordinate (L or G) for each control point.

- *coord3* (**PLFLT\_VECTOR**(3plplot), input)

  A vector containing the third coordinate (S or B) for each control point.

- *alpha* (**PLFLT\_VECTOR**(3plplot), input)

  A vector containing the alpha transparency value (0.0-1.0) for each control point.

- *alt\_hue\_path* (**PLBOOL\_VECTOR**(3plplot), input)

  A vector (with *npts - 1* elements) containing the alternative interpolation method Boolean value for each control point interval.  (alt\_hue\_path\[i\] refers to the interpolation interval between the i and i + 1 control points).

## AUTHORS

Many developers (who are credited at http://plplot.org/credits.php) have contributed to PLplot over its long history.

## SEE ALSO

PLplot documentation at http://plplot.org/documentation.php.