`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 (0.0-1.0) 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` (``PLFLT_VECTOR``, input)

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

`coord1` (``PLFLT_VECTOR``, input)

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

`coord2` (``PLFLT_VECTOR``, input)

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

`coord3` (``PLFLT_VECTOR``, input)

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

`alpha` (``PLFLT_VECTOR``, input)

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

`alt_hue_path` (``PLBOOL_VECTOR``, 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).

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

This function is used in example 30.

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