====== DRAW ======
/* Remove the comments after creating content for each section.*/
At least three very different ways to show pictures or create polygons on a graphical screen, according to implementation.


**Implemented by:** [[:basics:ANSI:ansifull]], [[:basics:Applesoft:]], [[:basics:CBM:cbmv7]], [[:basics:CBM:cbmv3.5]], [[:basics:trscolor:colorext]], [[:basics:Sinclair:spectrum]], [[:basics:ABasiC:]], [[:basics:VBDOS:]], [[:basics:FreeBASIC:]]

**With variations:** [[:basics:CBM:Simons1]], [[:basics:Atom:]] (line from current position to X,Y), [[:basics:BBC:]] (line from current position to X,Y), [[:basics:GWBASIC:]] (macro language), [[:basics:MSX:]] (macro language), [[:basics:msqb:QBasic]] (macro language), [[:basics:ugBASIC:]] (coordinates and DRAW TO form)

**Also written as: ** 
  * dR ([[:basics:CBM:cbmv3.5]])

===== Usage =====

The official [[:basics:ansi:ansifull|ANSI]] definition for DRAW was somewhat similar to the one which had been already implemented by [[:basics:Applesoft]] BASIC. As such, DRAW is used to show on screen a //predefined shape//.


==== Coordinates: From ... To... To... To... ====

In such implementations, DRAW is somewhat similar to the [[LINE]] statement found in some BASICs.

In [[:basics:cbm:cbmv3.5|Commodore BASIC V3.5]], it optionally defines a starting X,Y point with [[FROM]] and may have an arbitrary number of [[TO]] coordinates thereafter. Before the coordinates a numerical argument may be used for defining a //color source//:
  * 0 for the current screen background color
  * 1 for the current screen foreground color (default, can be ommited, but leave the comma there)
  * 2 for extra color 1 in multicolor mode
  * 3 for extra color 2 in multicolor mode

The following example from //Programmer's Reference Guide for the Commodore Plus/4// uses DRAW with the default foreground color:

<code gwbasic>
5 GRAPHIC 1,1

10 DRAW, 30,85 TO 289,150

20 DRAW, 160,85 TO 310,50 TO 840,100 TO 160,100 TO 80,50 

30 DRAW, TO 319,50
</code>

==== Microsoft's "graphical macro language" ====

Later [[:basics:ms80basic|Microsoft BASIC-80]]-derived implementations, such as [[:basics:gwbasic|GW-BASIC]], [[:basics:msx|MSX-BASIC]] and [[:basics:MSQB|QuickBASIC]], had a radically different implementation of DRAW with a striking resemblance to the "turtle graphics" made famous by the Logo language, which enjoyed a certain popularity in the early 1980s.

In such implementations, DRAW only interprets a string made of commands from a "macro language", like this short example from //Linguagem BASIC MSX//:

<code gwbasic>
DRAW "U20D10L30R40"
</code> 



^ command ^ meaning ^ obs ^
| Un | Up, //n// pixels  |  |
| En | Up-right, 45°, //n// pixels |  |
| Rn | Right, //n// pixels |  |
| Fn | Down-right, 45°, //n// pixels |  |
| Dn | Down, //n// pixels |  |
| Gn | Down-left, 45°, //n// pixels |  |
| Ln | Left, //n// pixels |  |
| Hn | Up-left, 45°, //n// pixels |  |
| Cn | Change the "pen" color to //n// | |
| Mx,y | From current position to coordinates //x,y// | |
| M±x,±x | From current position to plus/minus //x//, plus/minus //y// | |
| TAn | Rotates //n// integer degrees, from -360 to 360 (yes, no radians here) | |
| An | Rotates the whole coordinates system in 90° counter-clockwise, from 0 (default) to 4 | |
| Pi,o | Paint area with color //i// up to an area with color //o// | Not in [[:basics:msx]] |
| =V; | Substitutes numerical variable //V// within the commands string (don't forget the semicolon) | To confirm support on [[:basics:msqb]] |
| Xv$; | Substitutes string variable //v$// within the commands string (don't forget the semicolon) | |


Every command can also have a //prefix// which change its behavior:

| B | Only move according to the command, without actually drawing |
| N | Return to starting point after execution (in other words: perform without changing the current start location) | 

Still about variable substitution, it is possible to join the command string to a numerical string defined elsewhere by using [[VARPTR-S|VARPTR$]] in [[:basics:msqb:]] and [[:basics:gwbasic:]]. A command that waits a numeric argument is "left waiting" with the use of ''='', like the following example:

<code gwbasic>
DRAW "A0C4BM10,10R=" + VARPTR$(s$)
</code>


===== Comments =====
/* Origin of the keyword, opinions, history... */

===== Related keywords =====
/* Keywords that are often or always used along this one */
  * [[varptr-s|VARPTR$]]

===== Similar keywords =====
/* Keywords with the same or similar functionality found in other versions of BASIC */

===== In other languages... =====
/* For parallels and comparisons with other modern-day languages */

===== References =====
/* If you used the ((citation)) syntax elsewhere in the text, they will appear under this section. But you can write some recommendations of books, magazines, etc */
  * MERTEN, Cyndie; MEYER, Sarah. //Programmer's Reference Guide for the Commodore Plus/4//. Scott, Foresman and Company. USA, 1986. Available at https://archive.org/details/Plus-4_Programmers_Reference_Guide , last check 2023-03-12.
  * //Linguagem BASIC MSX//. Gradiente. Editora ALEPH. Brasil, 1986.
  * https://robhagemans.github.io/pcbasic/doc/2.0/#DRAW , last checked 2023-03-12

{{tag>Statements Graphics}}