SET LOCAL TRANSFORMATION 3

PSLMT3

CALL SEQUENCE

CALL PSLMT3 (XFRMT, CTYPE)

INPUT PARAMETERS

REAL XFRMT(4,4)

Homogeneous 4 x 4 transformation array to be applied to the current LOCAL MODELLING TRANSFORMATION array.

INTEGER CTYPE

Specifies XFRMT array composition method with the Local Modelling Transformation.

The possible values are:

- PCPRE

0 (PRECONCATENATE)

- PCPOST

1 (POSTCONCATENATE)

- PCREPL

2 (REPLACE)

PHIGS STATE

EFFECT

When the SET LOCAL TRANSFORMATION 3 element is interpreted, the specified array is used to modify the current local modelling transformation array depending on the CTYPE parameter (see below).

The local modelling transformation thus modified combines with the current global modelling transformation array to create a new composite modelling transformation.

The composite modelling transformation transforms the modelling coordinates (MC) of the current structure primitives into a world coordinates (WC) unified space. The application can thus define spaces specific to the elements created, which are then put into a unified space.

Array composition:

The local modelling transformation (L) is defined in the structure by the SET LOCAL TRANSFORMATION or SET LOCAL TRANSFORMATION 3 functions. If these functions are not defined in the structure, L equals the identity matrix. When execution of a structure starts during a traversal, the global modelling transformation (G) is equal to the composite modelling transformation (C) inherited from the parent structure.

The composite modelling transformation of a structure is constructed by multiplying the local modelling transformation and the global modelling transformation in the following manner: C = G x L.

Array composition method:

T being the matrix specified as input of the function.

Replacement:

CTYPE = PCPRE

L <----T

C <----G x L

Preconcatenation:

CTYPE = PCPOST

L <----L x T

C <----G x L

Postconcatenation:

CTYPZ = PCREPL

L <----T x L

C <----G x L

EXTENSION TO THE PHIGS STANDARD

If GPHIGS is in NRS mode, the effect of this function is different from the effect described in the standard.

In NRS mode, (see OPEN PIPE), the element is not stored in a structure. It is sent to the workstation on which the pipe is opened.

ERRORS

5

Ignoring function, function requires state (PHOP,*, STOP,*)

SEE ALSO

set global transformation 3, translate 3, scale 3, rotate x, rotate y, rotate z, compose matrix 3, build transformation matrix 3, compose transformation matrix 3, open structure, open pipe (ext), inquire current element content, inquire current element type and size