BR - Bezier relative ; BZ - Bezier absolute ; BR [ X1, Y1, X2, Y2, X3, Y3 . . . [X1, Y1, X2, Y2, X3, Y3]] [;] - Page 172

2001/10/02 

CHAPTER 4 HP-GL/2 - 24 

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To avoid placing an unwanted dot at the centre of the circle precede the CI command with a PU command. 

10 '-- Circle -- 

20 WIDTH "LPT1:",255 

30 LPRINT CHR$(27);"E"; 

40 LPRINT CHR$(27);"%0B"; 

50 LPRINT "IN;SP1;"; 

60 LPRINT "SC-75,75,-75,75,1;" 

70 LPRINT "PA0,0;LT;CI5;LT0;CI-12;" 

80 LPRINT "LT1;CI19;LT2;CI-26;" 

90 LPRINT "LT3;CI33;LT4;CI-40;" 

100 LPRINT "LT5;CI47;LT6;CI54;" 

110 LPRINT CHR$(27);"%0A"; 

120 LPRINT CHR$(27); "E"; 

130 END 

<Sample 30> 

BR - Bezier relative  

BR [ X1, Y1, X2, Y2, X3, Y3 . . .  [X1, Y1, X2, Y2, X3, Y3]] [;] 

X1, X2, X3 ; X coordinate of the second (X1), third (X2), and forth (X3) control point 
Y1, Y2, Y3 ; Y coordinate of the second (Y1), third (Y2), and forth (Y3) control point 

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Coordinates are relative values in current units. 

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Using the current pen position as the starting point,  the bezier curve is geometrically drawn referring to the 
other three points.  The start point of the curve is at (X0,Y0), and the curve is tangential to the line from (X0, 
Y0) to (X1, Y1) at that point,  and it leaves the point in that direction.  The end point of the curve is at 
(X3,Y3), and the curve is tangential to the line from (X2,Y2) to (X3,Y3).   

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After execution of this command the cursor position is at the end of the bezier curve. 

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When drawing a bezier curve is repeated, the last (fourth) control point of the first curve is used as the first 
control point for the second curve. 

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Plotting takes place only when the pen is down. 

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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. 

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If the curve extends to the outside of the soft/hard clip limit,  it is clipped. 

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This command can only be used in polygon mode. 

BZ - Bezier absolute 

BZ [ X1, Y1, X2, Y2, X3, Y3 . . .  [X1, Y1, X2, Y2, X3, Y3]] [;] 

X1, X2, X3 ; X coordinate of the second (X1), third (X2), and forth (X3) control point 
Y1, Y2, Y3 ; Y coordinate of the second (Y1), third (Y2), and forth (Y3) control point 

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Coordinates are absolute values in current units. 

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Using the current pen position as the starting point,  the bezier curve is g eometrically drawn referring to the 
other three points.  The start point of the curve is at (X0,Y0), and the curve is tangential to the line from (X0, 
Y0) to (X1, Y1) at that point,  and it leaves the point in that direction.  The end point of the curve is  at 
(X3,Y3), and the curve is tangential to the line from (X2,Y2) to (X3,Y3).   

• 

After execution of this command the cursor position is at the end of the bezier curve. 

• 

When drawing a bezier curve is repeated, the last (fourth) control point of the first curve is used as the first 
control point of the second curve. 

• 

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. 

• 

If the curve extends to the outside of the soft/hard clip limit,  it is clipped. 

• 

This command can only be used in polygon mode.