# plscmap1a.3plplot - Man Page

Set semitransparent cmap1 RGBA colors.

## Synopsis

**plscmap1a**(*r*, *g*, *b*, *alpha*, *ncol1*)

## Description

Set semitransparent cmap1 colors (see the PLplot documentation) using RGBA vector values. This function also sets the number of cmap1 colors. N.B. Continuous cmap1 colors are indexed with a floating-point index in the range from 0.0-1.0 which is linearly transformed (e.g., by **plcol1**(3plplot)) to an integer index of these RGBA vectors in the range from 0 to *ncol1-1*. So in order for this continuous color model to work properly, it is the responsibility of the user of **plscmap1**(3plplot) to insure that these RGBA vectors are continuous functions of their integer indices.

Redacted form: **plscmap1a(r, g, b, alpha)**

This function is used in example 31.

## Arguments

*r*(**PLINT_VECTOR**(3plplot), input)A vector that represents (using unsigned 8-bit integers in the range from 0-255) the degree of red in the color as a continuous function of the integer index of the vector.

*g*(**PLINT_VECTOR**(3plplot), input)A vector that represents (using unsigned 8-bit integers in the range from 0-255) the degree of green in the color as a continuous function of the integer index of the vector.

*b*(**PLINT_VECTOR**(3plplot), input)A vector that represents (using unsigned 8-bit integers in the range from 0-255) the degree of blue in the color as a continuous function of the integer index of the vector.

*alpha*(**PLFLT_VECTOR**(3plplot), input)A vector that represents (using PLFLT values in the range from 0.0-1.0 where 0.0 corresponds to completely transparent and 1.0 corresponds to completely opaque) the alpha transparency of the color as a continuous function of the integer index of the vector.

*ncol1*(**PLINT**(3plplot), input)Number of items in the

*r*,*g*,*b*, and*alpha*vectors.

## 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.