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7.1 Conventions Used In Describing Argument Types ¶

The following symbols are used to describe argument types in the documentation for GCL functions.

appearance

is an OOGL appearance specification.

cam-id

is an id that refers to a camera.

camera

is an OOGL camera specification.

geom-id

is an id that refers to a geometry.

geometry

is an OOGL geometry specification.

id

is a string which names a geometry or camera. Besides those you create, valid ones are:

World, world, worldgeom, g0

the collection of all geom’s

target

selected target object (cam or geom)

center

selected center-of-motion object

targetcam

last selected target camera

targetgeom

last selected target geom

focus

camera where cursor is (or most recently was)

allgeoms

all geom objects

allcams

all cameras

default, defaultcam, prototype

future cameras inherit default’s settings

The following ids are used to name coordinate systems, e.g. in pick and write commands:

World, world, worldgeom, g0

the world, within which all other geoms live.

universe

the universe, in which the World, lights and cameras live. Cameras’ world2cam transforms might better be called universe2cam, etc.

self

"this Geomview object". Transform from an object to self is the identity; writing its geometry gives the object itself with no enclosing transform; picked points appear in the object’s coordinates.

primitive

(for pick only) Picked points appear in the coordinate system of the lowest-level OOGL primitive.

A name is also an acceptable id. Given names are made unique by appending numbers if necessary (i.e. foo<2>). Every geom is also named g[n] and every camera is also named c[n] (g0 is always the worldgeom): this name is used as a prefix to keyboard commands and can also be used as a GCL id. Numbers are reused after an object is deleted. Both names are shown in the Object browser.

statement

represents a function call. Function calls have the form (func arg1 arg2 … ), where func is the name of the function and arg1, arg2, … are the arguments.

transform

is an OOGL 4x4 transformation matrix.

ntransform

is an OOGL (N+1)x(N+1) transformation matrix.

window

is an OOGL window specification.