AR - Draw relative arc ; AT - Absolute arc three point ; AR X, Y, - Page 169

2001/10/02 

CHAPTER 4 HP-GL/2 - 21 

AR - Draw relative arc 

AR X, Y, 

qc

(, 

qd

)[;] 

X ; Arc centre X coordinate 

Y ; Arc centre Y coordinate 

qc

 ; Arc angle in degrees   

qd

 ; Chord angle in degrees   

• 

Coordinates are relative values in current units. 

• 

Starting from the current cursor position the command plots an arc whose centre is at the relative coordinate 
position (X,Y) and which has the specified arc and chord angles.  The radius of the arc is the distance 
between the current position and the point (X,Y). 

• 

After execution of the command the cursor position is at the opposite end of the arc from the point at which 
plotting started. 

• 

Plotting takes place only when the pen is down. 

• 

If the command is invoked with the pen up,  plotting is not performed,  but the cursor position moves to 
what would have been the plot end point. 

• 

The value for 

qc

 is a clamped real number. 

• 

When 

qc

 is positive, plotting is counterclockwise. 

• 

When 

qc

 is negative, plotting is clockwise. 

• 

The value for 

qd

 is a clamped real number in the range 0.5° to 180°.  The default value is 5°. 

10 '--Draw Relative Arc -- 

20 WIDTH "LPT1:", 255 

30 LPRINT CHR$(27); "E"; 

40 LPRINT CHR$(27); "%0B"; 

50 LPRINT "IN;SP1;IP1000,1000,6000,6000;" 

60 LPRINT "SC-100,100,-100,100;" 

70 LPRINT  

"PA-100,70;PD;PR30,0;AR0,-70,-90,15;AR70,0,90;PR60,0;PU;" 

80 LPRINT CHR$(27); "%0A"; 

90 LPRINT CHR$(27); "E"; 

100 END 

<Sample 27> 

AT - Absolute arc three point 

AT X

1

, Y

1

, X

2

, Y

2

 [,

qd

] [;] 

X

1

 ; x-coordinate of intermediate point 

Y

2

 ; y-coordinate of intermediate point 

X

2

 ; x-coordinate of end point 

y

2

 ; y-coordinate of end point 

qd

 ; the chord angle used to draw the arc   

• 

All coordinates are absolute and in current units. 

• 

The command draws an arc from the current position,  through the specified intermediate position and 
finishing at the specified end position. 

• 

After completion of the command the current cursor position is at the end of the arc. 

• 

An arc can be drawn clockwise or anti-clockwise. 

• 

If the current scaling mode is not isotropic,  the arc may be elliptical rather than circular. 

• 

The chord angle must be in the range 0.5° to 180°. 

• 

The default chord angle is 5°. 

10 '--Absolute Arc Three Point-- 

20 WIDTH "LPT1:",255 

30 LPRINT CHR$(27);"E"; 

40 LPRINT CHR$(27);"%0B"; 

50 LPRINT "IN;SP1;"; 

60 LPRINT "PA1000,100;PD2500,100;" 

70 LPRINT "PU650,1150;PD1000,1150;" 

80 LPRINT "PU650,450;PD1000,450;" 

90 LPRINT "PU1000,100;PD1000,1500,2500,1500;" 

100 LPRINT "AT3200,800,2500,1500;" 

110 LPRINT "PU3200,900;PD;" 

120 LPRINT "AT3300,800,3200,700;" 

130 LPRINT "PU3300,800;PD3500,800;" 

140 LPRINT CHR$(27);"%0A"; 

150 LPRINT CHR&(27);"E"; 

160 END 

<Sample 28>