Elements for Visualization

LIGHT

LIGHT red, green, blue, shadow,
        radius, alpha, beta, angle_falloff,
        distance1, distance2,
        distance_falloff [[,] ADDITIONAL_DATA name1 = value1,
        name2 = value2, ...]

A light source radiates [red, green, blue] colored light from the local origin along the local x axis.
The light is projected parallel to the x axis from a point or circle source.
It has its maximum intensity within the alpha-angle frustum of a cone and falls to zero at the beta-angle frustum of a cone.
This falloff is controlled by the angle_falloff parameter.
(Zero gives the light a sharp edge, higher values mean that the transition is smoother.)
The effect of the light is limited along the axis by the distance1 and distance2 clipping values.
The distance_falloff parameter controls the decrease in intensity depending on the distance.
(Zero value means a constant intensity; bigger values are used for stronger falloff.)

GDL transformations affect only the starting point and the direction of the light.

shadow: controls the light’s shadow casting.
0: light casts no shadows,
1: light casts shadows.

http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_light.png
alpha <= beta <= 80°

The following parameter combinations have special meanings:

radius = 0, alpha = 0, beta = 0:
A point light, it radiates light in every direction and does not cast any shadows.
The shadow and angle_falloff parameters are ignored, the values shadow = 0, angle_falloff = 0 are supposed.

radius > 0, alpha = 0, beta = 0:
A directional light with parallel beams.

http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_light_cone3.png

r = 0, alpha > 0, beta > 0:
A directional light with conic beams.

http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_light_cone1.png

r > 0, alpha = 0, beta > 0:
A directional light with parallel beam and conic falloff.

http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_light_cone2.png

Light definitions can contain optional additional data definitions after the ADDITIONAL_DATA keyword.
Additional data has a name (namei) and a value (valuei), which can be an expression of any type, even an array.
If a string parameter name ends with the substring “_file”, its value is considered to be a file name and will be included in the archive project.

Different meanings of additional data can be defined and used by the executing application.

Example 1:

LIGHT 1.0,0.2,0.3,   ! RGB
        1,             ! shadow on
        1.0,           ! radius
        45.0, 60.0,    ! angle1, angle2
        0.3,           ! angle_falloff
        1.0, 10.0,     ! distance1, distance2
        0.2            ! distance_falloff


Example 2:

The library part dialog box for lights in :

http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_light_dialog.PNG

Part of the corresponding GDL script:

if gs_light_switch > 0 then
    LIGHT	gs_light_intensity/100*gs_color_red, 
			gs_light_intensity/100*gs_color_green, 
			gs_light_intensity/100*gs_color_blue, ! RGB
            ...
endif

PICTURE

PICTURE expression, a, b, mask

A picture element for photorendering.

http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_picture.png

A string type expression means a file name, a numeric expression or the index of a picture stored in the library part.
A 0 index is a special value that refers to the preview picture of the library part.
Other pictures can only be stored in library parts when saving the project or selected elements containing pictures as GDL Objects.

Indexed picture reference cannot be used in the MASTER_GDL script when attributes are merged into the current attribute set.
The image is fitted on a rectangle treated as a RECT in any other 3D projection method.

mask: alpha + distortion

alpha: alpha channel control.
0: do not use alpha channel; picture is a rectangle,
1: use alpha channel; parts of the picture may be transparent.

distortion: distortion control.
0: fit the picture into the given rectangle,
2: fit the picture in the middle of the rectangle using the natural aspect ratio of the picture,
4: fill the rectangle with the picture in a central position using natural aspect ratio of the picture.

distortion=0 distortion=2 distortion=4
http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_picture_distortion.png
http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_picture_fillrect1.png
http://gdl.graphisoft.com/wp-content/uploads/ac19-gdl/3Dshapes_picture_fillrect2.png