Topic       : TOS - The Operating System
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Version     : tos.hyp (December 19, 2008)
Subject     : Programmieren/Atari
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Compiled on : Atari
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View Ref-File6.8  Arbitrary line                                                TOS

 Name:         »Arbitrary line«

 Line-A number: $A003

 Syntax:       See 'Bindings for draw_line'

 Description:  This Line-A function draws a straight line from top 
               left to bottom right. The following Line-A variables 
               are used:

                Variable  Meaning

                x1        X-coordinate of the first end-point
                y1        Y-coordinate of the first end-point
                x2        X-coordinate of the second end-point
                y2        Y-coordinate of the second end-point
                fg_bp_1   Bit value of the first plane for the colour 
                          that should be used for filling
                fg_bp_2   Bit value of the second plane (only low or 
                          medium resolution)
                fg_bp_3   Bit value of the third plane (only low 
                          resolution)
                fg_bp_4   Bit value of the fourth plane (only low 
                          resolution)
                ln_mask   Bit pattern for the line type; the bit 
                          pattern is to be interpreted as a dot 
                          pattern
                wrt_mode  Writing mode; the following modes are 
                          possible:
                           REPLACE 0  Replace
                           TRANS 1    Transparent (OR)
                           XOR 2      Inverse (XOR)
                           INVERS 3   Inverse Transparent (XOR with 
                                      not(LN_MASK))
                lstlin    Is the last pixel of the line to be drawn 
                          (1) or not (0)

               Note: Independent of the order of the coordinates, the 
               line is drawn always from top left to bottom right.

               For a horizontal line there is a faster function $A004 
               Horizontal line available.

               The bindings of TC passes the line mask, writing mode 
               and colour not to the draw_line function, but uses 
               separate functions set_fg_bp, set_ln_mask and 
               set_wrt_mode for setting the parameters in the Line-A 
               parameter block.

 Return value: The function does not return a result. The field 
               ln_mask of the Line-A parameter block is shifted by the 
               output algorithm.

 Availability: All TOS versions.

 See Also:     Binding   LINEA   Horizontal line