COMPOSE TRANSFORMATION MATRIX 3(3P) — Kubota Pacfic Computer Inc. (29 February 1991)

NAME

COMPOSE TRANSFORMATION MATRIX 3 − compose a 3D transformation matrix, which is the composition of a specified matrix and a transformation matrix defined by a fixed point, shift vector, rotation angle, and scale factors

SYNOPSIS

C Syntax

void
pcompose_tran_matrix3 ( m, pt, shift, x_ang, y_ang, z_ang, scale, error_ind, result )
Pmatrix3m;transformation matrix
Ppoint3∗pt;fixed point
Pvec3∗shift;shift vector
Pfloatx_ang;rotation angle X
Pfloaty_ang;rotation angle Y
Pfloatz_ang;rotation angle Z
Pvec3∗scale;scale vector
Pint∗error_ind;OUT error indicator
Pmatrix3result;OUT transformation matrix

Required PHIGS Operating States

(PHOP, ∗, ∗, ∗)

DESCRIPTION

Purpose

Use COMPOSE TRANSFORMATION MATRIX 3 to generate a 3D (4 × 4) matrix that composes an existing 4 × 4 matrix with a transformation specified by 3D values for scaling, rotation, and translation about a fixed point.

The returned matrix may be passed as an argument to SET LOCAL TRANSFORMATION 3 or SET GLOBAL TRANSFORMATION 3 to modify the modelling transformation applied to output primitives during traversal.

C Input Parameters

mThe 3D (4 × 4) homogeneous transformation matrix to use in the composition. This matrix is a Pmatrix3 type, defined in phigs.h as follows: typedef Pfloat Pmatrix3[4][4];

ptA pointer to a Ppoint3 structure containing the x, y, and z and coordinates of a fixed point in Modelling Coordinates. Scaling and rotation are performed relative to this fixed point. Ppoint3 is defined in phigs.h as follows:

typedef struct {
Pfloatx;/∗ x coordinate ∗/
Pfloaty;/∗ y coordinate ∗/
Pfloatz;/∗ z coordinate ∗/
} Ppoint3;

shiftA pointer to a Pvec3 structure containing x, y, and z coordinates defining the shift (translation) to be added to the transformation. Pvec3 is defined in phigs.h as follows:

typedef struct {
Pfloatdelta_x;/∗ x magnitude ∗/
Pfloatdelta_y;/∗ y magnitude ∗/
Pfloatdelta_z;/∗ z magnitude ∗/
} Pvec3;

x_ang, y_ang, z_ang
The angles of rotation about the indicated axes, in radians, to be added to the transformation. A positive angle is a counter-clockwise rotation. A negative angle is clockwise rotation.

scaleA pointer to a Pvec3 structure containing x, y, and z values defining the scale factors to be applied to the transformation.

C Output Parameters

error_ind
A pointer to the location to store the error number of any error detected by this function.

resultThe resulting 3D (4 × 4) transformation matrix.

Execution

COMPOSE TRANSFORMATION MATRIX 3 returns the matrix that performs the transformation resulting from the composition of the input matrix and the matrix specified by the input parameters shift, angle, and scale. Rotation and scaling are calculated relative to the fixed point.

The composition is performed as: result = a x b

Where b is the input matrix and a is the matrix built from the other input parameters.

The order of operations used to build the transformation matrix b is:

• scale
• rotate
• shift (translate)

ERRORS

002Ignoring function, function requires state (PHOP, ∗, ∗, ∗)

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