EVALUATE VIEW MAPPING MATRIX 3

PEVMM3

CALL SEQUENCE

CALL PEVMM3	(VWWNLM, PJVPLM, PJTYPE, PJRX, PJRY, PJRZ, VPLD, BPLD, FPLD, ERRIND, VWMPMT)

INPUT PARAMETERS

REAL VWWNLM(4)

View window limits in VRC: UMIN, UMAX, VMIN, VMAX.

REAL PJVPLM(6)

Values (XMIN, WMAX, YMIN, YMAX, ZMIN, ZMAX) in NPC define the Viewport in the NPC space in which the VRC volume defined by parameters (VWWNLM, PJTYPE, PJRX, PJRY, PJRZ, VPLD, BPLD, FPLD) will be projected.

INTEGER PJTYPE

Type of projection used to define the VRC view volume.

- PPARL:

0 (PARALLEL)

- PPERS:

1 (PERSPECTIVE)

REAL PJRX, PJRY, PJRZ

Projection Reference Point PRP defined in VRC space.

REAL VPLD

VRC N axis distance which defines the position of the view plane. This plane is parallel to plane UV and defines the position of VWWNLM in the view volume which will be projected in NPC.

REAL BPLD

VRC N axis distance which defines the position of the back plane. This plane is parallel to plane UV and defines the back of the view volume which will be projected in NPC.

REAL FPLD

VRC N axis distance which defines the position of the front plane. This plane is parallel to plane UV and defines the front of the view volume which will be projected in NPC.

OUTPUT PARAMETERS

INTEGER ERRIND

Error indicator

REAL VWMPMT(4,4)

Resulting homogeneous (4 x 4) 3D matrix.

PHIGS STATE

EFFECT

Returns a homogeneous 4 x 4 matrix allowing a 3D view reference coordinate (VRC) space window to be projected into a 3D viewport in normalized projection coordinate (NPC) space. This projection, which can be in parallel or in perspective, is defined according to the projection reference point (PRP), defined in VRC.

- Parallel projection: the view volume sides are parallel to the vector passing through the PRP and the centre of the view plane.

- Perspective projection: the view volume sides converge towards the PRP.

ERRORS

2

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

151

Ignoring function, invalid window: XMIN>=XMAX, YMIN>=YMAX, ZMIN>ZMAX, UMIN>=UMAX or VMIN>=VMAX

152

Ignoring function, invalid viewport: XMIN>=XMAX, YMIN>=YMAX or ZMIN>ZMAX

158

Ignoring function, front plane and back plane distances are equal when: extent of the projection viewport is non zero

162

Ignoring function, the projection reference point is between the front and back planes

163

Ignoring function, the projection reference point cannot be positioned on the view plane

164

Ignoring function, the back plane is in front of the front plane

155

Ignoring function, the projection viewport limits are not within NPC range

SEE ALSO

set view representation, evaluate view orientation matrix