NAME

DoDepthCue − Create a primitive attribute object defining depth cueing

SYNOPSIS

C:

DtObject DoDepthCue(zfront, zback, sfront, sback, colormodel, color)
DtReal zfront, zback, sfront, sback;
DtColorModel colormodel;
DtReal color[];

Fortran:

INTEGER∗4 DODC(ZFRONT, ZBACK, SFRONT, SBACK, COLMOD, COLOR)
REAL∗8 ZFRONT, ZBACK, SFRONT, SBACK
INTEGER∗4 COLMOD
REAL∗8 COLOR(∗)

DESCRIPTION

DoDepthCue creates a depth cue primitive attribute object.  The object is used to specify how primitive objects will be depth cued when the depth cue switch primitive attribute (set by DoDepthCueSwitch <DODCS>) is enabled.  Note that depth cueing is on an object-per-object basis. 

When the depth cue switch is enabled, a user-provided color is combined with that of any primitive object proportional to each part’s distance from the viewer (i.e., Z-values in frame coordinates).  If the depth cue switch is disabled, then the primitive object’s color is unaffected. 

The zfront and zback values define two planes:  Z-values in frame coordinates of two planes parallel to the XY plane.  The sfront and sback values are numbers between 0 and 1 specifying the portion between the primitive’s color and user-supplied depth cue color color to be used at each plane.  The values for Z-values between sfront and sback are linearly interpolated.  Note that the required parameter colormodel establishes the color model of the color parameter. 

The displayed color DC at some depth Z in frame coordinates is related to the primitive’s color C, the depthcue color color, the front and back Z-planes zfront and zback (with their associated values sfront and sback) as follows:

If Z is in front of zfront, then

DC = sfront∗C+(1-sfront)∗color

If Z is behind zback, then

DC = sback∗C+(1-sback)∗color

If Z is between zfront and zback and if

r = sback+(((Z-zback)∗(sfront-sback))/(zfront-zback))

then

DC = r∗C+(1-r)∗color.

DEFAULTS

The default settings of DoDepthCue are (1.0, 0.0, 1.0, 0.0, DcRGB, (0.0, 0.0, 0.0)). 

SEE ALSO

DoDepthCueSwitch(3D)

September 29, 2021