`plscmap1la`: Set cmap1 colors and alpha transparency using a piece-wise linear relationship
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#### `plscmap1la`: Set cmap1 colors and alpha transparency using a piece-wise linear relationship

`plscmap1la (` | itype,
| npts,
| intensity,
| coord1,
| coord2,
| coord3,
| alpha,
| alt_hue_path`)`;

This is a variant of `plscmap1l` that supports alpha channel transparency. It sets cmap1 colors using a piece-wise linear relationship between cmap1 intensity index (from 0. to 1.) and position in HLS or RGB color space (see the section called “Color Map1”) with ``alpha`` transparency value (0.0 - 1.0). It may be called at any time.

`itype` (`PLBOOL`, input)

  true: RGB, false: HLS.

`npts` (`PLINT`, input)

  number of control points

`intensity` (`const PLFLT *`, input)

  position for each control point (between 0.0 and 1.0, in ascending order)

`coord1` (`const PLFLT *`, input)

  first coordinate (H or R) for each control point

`coord2` (`const PLFLT *`, input)

  second coordinate (L or G) for each control point

`coord3` (`const PLFLT *`, input)

  third coordinate (S or B) for each control point

`alpha` (`const PLFLT *`, input)

  the alpha transparency value for each control point

`alt_hue_path` (`const PLBOOL *`, input)

  alternative interpolation method flag for each control point. (`alt_hue_path[i]` refers to the interpolation interval between the `i` and `i + 1` control points).

Redacted form: `plscmap1la(itype, intensity, coord1, coord2, coord3, alpha, alt_hue_path)`

This function is used in example 30.

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