POLY_C_CONV Function

Reference Guide > P Routines > POLY_C_CONV Function

Returns a list of colors for each polygon, given a polygon list and a list of colors for each vertex.

Usage

result = POLY_C_CONV(polygon_list, colors)

Input Parameters

polygon_list — An array containing a list of polygons. For more information, see the PV‑WAVE User’s Guide.

colors — A vertex-based color list.

Returned Value

result — An integer vector containing the list of colors, one color for each input polygon. (In other words, the result contains the same number of colors as the number of polygons in polygon_list.)

Keywords

None.

Discussion

POLY_C_CONV is useful for converting a vertex-based color list to a polygon-based list. For example, the SHADE_VOLUME procedure returns a list of polygon colors when the Shades keyword is used. This list has one color per vertex. The POLY_PLOT procedure, however, requires a color list with one color per polygon.

Example

This example program displays data warped onto an irregular sphere.

PRO sphere_demo2

   radii = RANDOMU(s, 60, 60)

   radii = SMOOTH((radii + 1.0), 2)

   ; Define the sphere as a list of polygons.

   POLY_SPHERE, radii, 60, 60, vertex_list, polygon_list

   ; Define the shading colors for the sphere.

   p_colors = BYTSCL(DIST(60), Top=127)

   ; Set up the viewing window and load the color table.

   WINDOW, 0, Colors=128, XPos=16, YPos=384

   LOADCT, 1

   CENTER_VIEW, Xr=[-2.0, 2.0], Yr=[-2.0, 2.0], $

      Zr=[-2.0, 2.0], Ax=(-75.0), Az=(-90.0), Zoom=0.99

   ; Construct a shaded surface representation of the data

   ; and display it using POLYSHADE.

   TVSCL, POLYSHADE(vertex_list, polygon_list, $

      /T3d, Shade=WoColorConvert(p_colors))

   ; Create a new window for a new plot.

   WINDOW, 1, Colors=128, XPos=256, YPos=64

   ; Count the number of polygons in the sphere.

   pg_num = POLY_COUNT(polygon_list)

   ; Transform polygon vertices from data coordinates to

   ; device coordinates.

   vertex_list = POLY_NORM(vertex_list)

   vertex_list = POLY_TRANS(vertex_list, !P.T)

   vertex_list = POLY_DEV(vertex_list, 640, 512)

   ; Convert colors from a vertex-based list to a

   ; polygon-based list.

   p_colors = POLY_C_CONV(polygon_list, p_colors(*))

   ; Plot the sphere using POLY_PLOT.

   POLY_PLOT, vertex_list, polygon_list, $

      pg_num, 640, 512, WoColorConvert(p_colors), 0, -1

END

For another POLY_C_CONV example, see the poly_demo1 demonstration program. This programs and others are found in:

(UNIX) <wavedir>/demo/arl

(WIN) <wavedir>\demo\arl

Where <wavedir> is the main PV-WAVE directory.