DCL:GRPH1:STPACK: Transformation Functions:Explanation of Subroutines: Coordinate Transformation
Performs 3-D perspective transformation.
CALL STFPR3(UX,UY,UZ,RX,RY)
CALL STSPR3(XFC,YFC,ZFC,THETA,PHI,PSI,FAC,ZVIEW,RXOFF,RYOFF)
UX,UY,UZ (R) The coordinates in UC. RX,RY (R) The coordinates in RC. ITR3 (I) Transformation function number XFC,YFC,ZFC (R) The coordinates of the center of focus THETA,PHI,PSI (R) The angle of rotation FAC (R) The scaling factor ZVIEW (R) The Z coordinate of the eye point RXOFF,RYOFF (R) The offset
- (a)
- These functions perform the following operations.
- Parallel transformation with the center of focus as the origin.
- Rotation of (THETA,PHI,PSI) around the origin..
- Multiplies the coordinate values by a factor of FAC.
- With the eye point at (0,0,ZVIEW), projects a point onto the X-Y plane.
- Adds an offset of (RXOFF,RYOFF) to the projected coordinate value.