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System Defined Variables
There are some variables which are defined as part of the SDL. These vari-ables are always defined, and may be referenced as desired. Their values are set and maintained automatically. In most cases (the exceptions will be noted), these vari-ables may not be updated or changed by the user.
The majority of the variables correspond to the operational parameters. Those that do correspond have a default value, but may be set from command line ar-guments or by assignment in the DEFINITION section. Each variable is described below. System Defined Constants are described after the variables.
The following variables are described in this topic.
This variable corresponds to the operational parameter aalevelmax. It has a default scalar value of 2, but may be set from the -a command line option (see Command Line Options) or by assign-ment in the DEFINITION Section. It sets the maximum anti-aliasing level that will be used when rendering an image. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the de-scription of DEFINITION parameters for the meaning of this data and the values that it may take.
It has a default scalar value of 1, but may be set by assign-ment in the DEFINITION Section. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the de-scription of DEFINITION parameters for the meaning of this data and the values that it may take.
This variable corresponds to the operational parameter aathreshold. It has a de-fault scalar value of 160, but may be set from the -t command line option (see Command Line Options) or by as-signment in the DEFINITION Section. Note that it may not be set by assign-ment (or by any other means) in any section except the DEFINITION section. See the descrip-tion of DEFINITION parameters for the meaning of this data and the values that it may take.
This variable corresponds to the operational parameter byframe. It has a default scalar value of 1, but may be set from the -b command line option (see Command Line Options) or by assign-ment in the DEFINITION Section. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the de-scription of DEFINITION parameters for the meaning of this data and the values that it may take.
This variable corresponds to the operational parameter endframe. It has a de-fault scalar value of 1, but may be set from the -e command line option (see Command Line Options) or by as-signment in the DEFINITION Section. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the description of DEFINITION parameters for the meaning of this data and the val-ues that it may take.
This variable takes on scalar values from startframe to endframe at intervals of byframe during the rendering process. It may be thought of as the sense of time, or current “frame” within an animation. It need not be an integer value. It may not be modified by the user in any way, nor will its value ever be outside the specified range.
This variable corresponds to the operational parameter quiet. It has a default scalar value of FALSE, but may be set from the -q command line option (see Command Line Options) or by as-signment in the DEFINITION Section. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the description of DEFINITION parameters for the meaning of this data and the val-ues that it may take.
This variable corresponds to the operational parameter startframe. It has a default scalar value of 1, but may be set from the -s command line option (see Command Line Options) or by assignment in the DEFINITION Section. Note that it may not be set by assign-ment (or by any other means) in any section except the DEFINITION section. See the description of DEFINITION parameters for the meaning of this data and the values that it may take.
This variable corresponds to the operational parameter xleft. It has a default scalar value of 0, but may be set from the -x command line option (see Command Line Options) or by assign-ment in the DEFINITION Section. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the de-scription of DEFINITION parameters for the meaning of this data and the values that it may take.
This variable corresponds to the operational parameter xright. It has a default scalar value of 644, but may be set from the -w command line option (see Command Line Options) or by as-sign-ment in the DEFINITION Section. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the description of DEFINITION parameters for the meaning of this data and the val-ues that it may take.
This variable corresponds to the operational parameter yhigh. It has a default scalar value of 485, but may be set from the -h command line option (see Command Line Options) or by as-signment in the DEFINITION Section. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the description of DEFINITION parameters for the meaning of this data and the val-ues that it may take.
This variable corresponds to the operational parameter ylow. It has a default scalar value of 0, but may be set from the -y command line option (see Command Line Options) or by assign-ment in the DEFINITION Section. Note that it may not be set by assignment (or by any other means) in any section except the DEFINITION section. See the description of DEFINITION parameters for the meaning of this data and the values that it may take.