Graphics Tutorial

Grammer offers much faster graphics over BASIC, but a good understanding of the lower-level graphics is what will make your graphics good.

The most important graphics command is DispGraph, located at [prgm][right][4]. In Grammer, graphics commands don't get rendered to the LCD like they do in BASIC. Updating the LCD is a relatively slow operation on the TI-83+/84+ series of calculators (the physical LCD is much slower than the Z80 processor), so the ability to defer updating the LCD offers the biggest boost in speed over BASIC graphics. This ability to defer is also what makes graphics smoother.

DispGraph

By default, DispGraph draws the graphscreen to the LCD. Here is an example:

.0:Return
DispGraph
Stop

When you run this from the homescreen, you will see something like:

You can also display an arbitrary graphics buffer. If you aren't familiar with graphics buffers, see the section on Graphics Buffers.

.0:Return
DispGraph0
Stop

This shows garbage because DispGraph is reading the start of memory (address 0) as if it is graphics data.

Disp

Most graphics routines allow you to provide an optional argument designating a graphics buffer to draw to. You can also set a default buffer with the Disp function. For example, Disp G-T' (or Disp π9872 on older versions). Now, whenever you draw or update the LCD, that is the buffer that will be used. This means you can preserve the graph screen while still using graphics in Grammer. Note that G-T is the token that you can see near the bottom of the mode menu.

As an example, let's set the secondary buffer as the default buffer and draw some text. This will preserve the graphscreen, since we aren't drawing there!

.0:Return
Disp G-T`
Text(0,0,"HELLO, WORLD!
DispGraph
Stop

Disp is also important if you want to use grayscale graphics. For the following examples, I will assume you know the basic ideas behind grayscale on these monochrome calculators. If not, brush up on grayscale. Internally, Grammer cleverly sources data from two graphics buffers to determine what to display to the LCD when using DispGraph. By default, "both" buffers point to the graph screen, so it is always reading the same color pixel from both sources, essentially displaying either black, or white, and never flickering between the two. Also by default, Grammer sources 50% of the color from one buffer, and 50% from the other. Here is an example that draws grayscale bars until the user presses [CLEAR]:

.0:Return
Disp °G-T'        ;Set the secondary buffer to appBackUpScreen, 0x9872
ClrDraw           ;Clear the primary buffer
ClrDrawG-T'       ;Clear the back buffer
Line(0,0,64,48    ;Draws a black rectangle on the left half of the main buffer
Line(0,0,64,24,1,G-T'    ;Draws a black rectangle on the left quarter of the back buffer
Line(48,0,64,24,1,G-T'   ;Draws a black rectangle on the third quarter of the back buffer
Repeat getKey(15  ;Repeat the loop until key 15 ([clear]) is pressed
DispGraph         ;Display the graph buffers
End
Stop

You can change how much color is sourced from each buffer by selecting a different gray mask. Grammer has 3 different grayscale modes (0,1, and 2), but realistically, modes 1 and 2 are most useful. Mode 1 is the default and sources 50% from each buffer. Mode 2 sources 67% from the primary buffer and 33% from the back buffer, allowing 4 different shades. Adding 2→Disp to the start of the above code:

.0:Return
2→Disp            ;Set to 67-33 grayscale mode
Disp °G-T'        ;Set the secondary buffer to appBackUpScreen, 0x9872
ClrDraw           ;Clear the primary buffer
ClrDrawG-T'       ;Clear the back buffer
Line(0,0,64,48    ;Draws a black rectangle on the left half of the main buffer
Line(0,0,64,24,1,G-T'    ;Draws a black rectangle on the left quarter of the back buffer
Line(48,0,64,24,1,G-T'   ;Draws a black rectangle on the third quarter of the back buffer
Repeat getKey(15  ;Repeat the loop until key 15 ([clear]) is pressed
DispGraph         ;Display the graph buffers
End
Stop

There is a mode that ORs the two buffers together before displaying. This is useful for an independent background (you could probably do paralax scrolling with this, or overworld sprites on top of a tilemap). This mode uses 16→Disp.

There is another mode useful for tilemaps that masks three buffers. This is done using the mode: 17→Disp. This ANDs the secondary buf with the tilemap_buf (used during smooth-scrolling tilemapping). It then XORs that with the primary buf. This is fantastic for adding overworld graphics without destroying the tilemap data (thus reducing rendering time, making things faster and smoother).

ClrDraw

ClrDraw clears the primary graphics buffer, setting it to white, and resets the text coordinates to the upper-left, (0,0). Alternatively, you can specify a graphics buffer to erase, for example: ClrDrawG-T' would clear the buffer that G-T' points to (typically used as a back buffer for grayscale).

ClrHome

This clears the home screen buffer and resets the cursor coordinates. This isn't really useful in Grammer as the homescreen is essentially unused, but it's good for aesthetics and advanced users.

Shade(

This sets the contrast to a value from 0 to 39. 24 is normal. An example is Shade(30.

Note: I am aware that the LCD actually offers 64 different shades, however, I deferred to the OS conventions. Why I did this is beyond me, but it's too late to change it.

Text(

There are many different methods for drawing text in Grammer. By default, it uses a 4x6 fixed-width font, and can draw to 24 columns (much like the TI-BASIC Output( command drawing to only 16 columns on the homescreen). Unlike TI-BASIC, Output( is instead used to change font settings. This lets you choose between grid-aligned and pixel-aligned drawing, or the small, fixed-width font, or the large variable-width font, or even custom fonts from Batlib and Omnicalc. You can find more on this in the Output( section.

Draw text strings

The most basic way to use Text( looks a lot like BASIC:

.0:Return
ClrDraw
Text(3,1,"HELLO, WORLD
DispGraph
Stop

This draws the text, "HELLO, WORLD" at three pixels down and 1 column (4 pixels) to the right.

You can also specify how many chars to print, with an optional fourth argument. Note: this will draw end-of-string characters instead of stopping early! For example:

.0:Return
ClrDraw
Text(4,1,"TOMATO",3
DispGraph
Stop

Or a little more exciting:

.0:Return
ClrDraw
Text(4,1,"HELLO",17
DispGraph
Stop

Draw numbers

To draw a number, use the ' modifier:

.0:Return
ClrDraw
Text('0,0,1337
DispGraph
Stop

This draws the number 1337 in the upper-left corner of the screen.

When drawing numbers, you can add an optional argument to change what base to draw the number in. For example, binary is base 2, so:

.0:Return
ClrDraw
Text('0,0,1337,2
DispGraph
Stop

Grammer uses "16-bit unsigned integers", but sometimes you'll want to draw "signed" numbers. If you don't know what these mean, check out the section on Number Systems.

To draw numbers as signed values, set the mode flag with Fix or 32 (see Fix Modes for more). Here is an example where we display the value of 3-4, which is -1. On the left, we omit the Fix or 32, so it displays as 65536-1=65535. On the right, we display it as signed, so it shows as -1

.0:Return
Fix or 32
ClrDraw
Text('0,0,3-4
DispGraph
Stop

Grammer also allows you to draw a 32-bit number stored in two pointer vars. An example where B is the upper 16-bits and C' is the lower 16-bits: :Text('0,0,BC' Or a more practical example, we can display a number including the overflow of multiplication. We'll make use of the 32-bit store described in the Basic Operations section:

.0:Return
ClrDraw
39103*136→AB
Text('0,0,AB
DispGraph
Stop

Follow text with more text

If you want to draw text where the last Text( command left off, use a degree token to replace coordinates: Text(°. For example, we'll display the numbers 3 and 4 with a comma separating them:

.0:Return
ClrDraw
Text('0,0,3
Text(°",
Text('°4
DispGraph
Stop

Note that ° came after ' when we wanted to display the 4. This is because the modifier ' comes before the coordinates when displaying numbers, and ° replaces the coordinates.

Typewriter text

"Typewriter text" is text displayed with a small pause between characters drawn. To use this effect, you can use /Text( or Text(^r (that is the superscript r found at [2nd][APPS]). You can change the delay with Fix Text( (see Fix Modes for more). Note: Typewriter text automatically updates the LCD.

.0:Return
ClrDraw
/Text(0,0,"HELLO, WORLD!
Stop

Typewriter text works with all of the text modes, not just strings!

Display Text Characters (ASCII, ish)

There are 256 characters in the font, some are more difficult to access via the OS tokens. In Grammer, you can directly draw chars by number if you put a ' before the last argument. For example, 37 corresponds to the % char:

.0:Return
ClrDraw
Text(4,1,'37
DispGraph
Stop

Note that if we want to draw a char to the last text coordinates, we put the ' after the °:

.0:Return
ClrDraw
Text('4,1,100
Text(°'37
DispGraph
Stop

Display text as ASCII, not tokens

Drawing ASCII is not intended for drawing text that you type in the program editor! If you don't know what a "null terminated string" is, then you probably don't want to use this! After this sentence, I will get technical and you should probably know Assembly or C to understand it.

In the event that you have an ASCII string that you would like to display, keep in mind that it must be null-terminated (ends in a 0x00). Display with the syntax, Text(Y,X,°<<pointer>>.

Miscellaneous Text Operations

If you want to draw to coordinates relative to the last drawn coordinates, you can do something like this: Text(+3,+0,"Hello. But instead of +0, just leave it empty like this: Text(+3,,"Hello

Using the Text( command with no arguments returns the Y position in Ans and the X position in Ɵ'.

You can set the coordinates without drawing text, too: Text(0,0.

Pxl-On(

The arguments for this are: Pxl-On(y,x[,buf. This draws a black pixel at coordinates (y,x), on buffer buf. If you omit the buf argument, this defaults to the current default buffer. As well, the previous pixel value is returned, with 0 indicating white, and 1 indicating black.

To set the upper-left pixel black, we can do:

Pxl-On(0,0

To set the bottom-right pixel black:

Pxl-On(63,95

Pxl-Off(

The arguments for this are: Pxl-Off(y,x[,buf. This draws a white pixel at coordinates (y,x), on buffer buf. If you omit the buf argument, this defaults to the current default buffer. As well, the previous pixel value is returned, with 0 indicating white, and 1 indicating black.

To set the upper-left pixel white, we can do:

Pxl-Off(0,0

To set the bottom-right pixel white:

Pxl-Off(63,95

Pxl-Change(

The arguments for this are: Pxl-Change(y,x[,buf. This toggles a pixel at coordinates (y,x), on buffer buf. If you omit the buf argument, this defaults to the current default buffer. As well, the previous pixel value is returned, with 0 indicating white, and 1 indicating black.

To toggle the upper-left pixel:

Pxl-Change(0,0

To toggle the bottom-right pixel:

Pxl-Change(63,95

Langton's Ant Example

An interesting application of Grammer's Pxl-Change( command is with Langton's Ant. Because a pixel test is built in, we can combine the test+toggle step. Here is an example that displays every 250 iterations, but only exits when you press [Clear].

:.0:Return
:Full
:ClrDraw
:0→D→C
:32→Y:48→X
:Repeat getKey(15
:Pxl-Change(Y,X
:+Ans+D-1
: and 3→D
:Y+D=0:-D=2→Y
:X+D=3:-D=1→X
:C+1→C
:If !C and 255
:DispGraph
:End
;Stop

Note: the and 3 and and 255 tricks only works for powers of 2! 3 is 2^2-1 and 255 is 2^8-1.

Pxl-Test(

The arguments for this are: Pxl-Test(y,x[,buf. This gets the pixel value at coordinates (y,x), on buffer buf. If you omit the buf argument, this defaults to the current default buffer. Returns 0 if the pixel is off (white), and 1 if the pixel is on (black).

Horizontal

This draws a horizontal line on the graph. The syntax is Horizontal y[,method,[,Buffer

y is a value from 0 to 63
method is how to draw the line:
- 0 = draws a white line
- 1 = draws a black line (Default)
- 2 = draws an inverted line
Buffer is the buffer to draw to.

For example, this will make a screen-wiping animation from the up and down directions:

:.0:Return
:For(K,0,31
:Horizontal K
:Horizontal 63-K
:DispGraph
:End
:Stop

Vertical

This draws a vertical line on the graph. The syntax is: Vertical x[,method[,Buffer

x is a value from 0 to 63
method is how to draw the line:
- 0 = draws a white line
- 1 = draws a black line (Default)
- 2 = draws an inverted line
Buffer is the buffer to draw to.

For example, this will make a screen-wiping animation from the left and right directions:

:.0:Return
:For(K,0,47
:Vertical K
:Vertical 95-K
:DispGraph
:End
:Stop

Screen Shifting

Tangent( is used to shift the screen a number of pixels. The syntax is: Tangent(#ofShifts,Direction[,Buffer #ofShifts is the number of pixels to shift the graph screen Direction is represented as a number:

1 = Down
2 = Right
4 = Left
8 = Up You can combine directions by adding the values. For example, Right and Up would be 10 because 2+8=10, so to shift the buffer contents right and up 4 pixels:
```
Tangent(4,10
```

Fill(

Fill( is a whole bunch of commands for buffer operations. For example, suppose you want to fill the buffer with black pixels. Then you can use Fill(0)

:.0:Return
:Fill(0
:DispGraph
:Stop

Or to invert the buffer:

:.0:Return
:Fill(1
:DispGraph
:Stop

You can also fill the screen buffer with a checkered pattern. There are two versions of this. I don't know how this is useful, but I won't judge:

:.0:Return
:Fill(2
:DispGraph
:Stop

:.0:Return
:Fill(3
:DispGraph
:Stop

Byte Patterns

You can fill the buffer with a byte pattern, too. For example, suppose you want to set every other pixel black. You will need to use OR logic, and a byte pattern of 85 or 170. This is because in binary, 85 is 01010101 and 170 is 10101010. So we'll use Fill( method number 4: Fill(4,byte - LoadBytePatternOR:

:.0:Return
:Fill(4,85
:DispGraph
:Stop

But you can also use method 5 to invert instead. To alternate inverting 2 pixels and then leaving 2 pixels ignored, we use a byte whose binary looks something like 11001100. In decimal, this is 204:

:.0:Return
:Fill(5,204
:DispGraph
:Stop

In this image I got rid of the axes and drew a sine curve beforehand:

Full buffer copies

Buffer copies are useful operations, especially for game graphics. These copy the data from one buffer to another. The most useful ones are probably the masking routines, allowing you to perform such operations as ORing or XORing one buffer on top of another. This is a little more complicated to show, but in this example, I've copied a sine graph into Pic1, and now I'll invert it onto the graphscreen:

:.0:Return
:Fill(11,Pic1
:DispGraph
:Stop

Shift-and-copy

These operations are pretty esoteric, honestly, but maybe you can find a use for them. These copy the current buffer up or down one pixel, masked back on top of the buffer. It can make some neat cellular automata effects, for example:

:.0:Return
:For(X,0,95
:Pxl-On(0,X
:Fill(16,1
:DispGraph
:End
:Stop

This marches a pixel on the top row from left to right, while XORing the buffer 1 pixel down onto itself.

Flames Graphics

Flames graphics are pretty cool, and might be useful in games. The flame functions have two modes: white fire and black fire. In white fire mode, any white pixels on the screen are shifted up and have some probability of turning black (dissipating, burning out). In black fire mode, it is the opposite.

Grammer has two commands to use these, one for the whole screen, and one for part of the screen. Here is an example where we take the contents of the graph screen as constant "fuel." To do this, we need to switch to another default buffer, then in a loop, we copy the graph buffer to the new buffer with OR logic and then perform one cycle of fire:

:.0:Return
:Disp G-T'
:ClrDraw
:Repeat getKey(15
:Fill(9,G-T
:Fill(22,1
:DispGraph
:End
:Stop

Note that G-T is the token found in the mode menu, or at [2nd] [0] [^] [up].

Fill( command summary

Stick around, this is a pretty full command list.

Fill(0 - Black
- This fills the screen buffer with black pixels
Fill(1 - Invert
- This inverts the screen buffer
Fill(2 - Checker1
- This fills the screen buffer with a checkered pattern
Fill(3 - Checker2
- This fills the screen buffer with another checkered pattern
Fill(4,byte - LoadBytePatternOR
- copies byte to every byte of the buffer data with OR logic
Fill(5,byte - LoadBytePatternXOR
- copies a byte to every byte of the buffer data with XOR logic
Fill(6,byte - LoadBytePatternAND
- copies a byte to every byte of the buffer data with AND logic
Fill(7,byte - LoadBytePatternErase
- copies a byte to every byte of the buffer data with Erase logic
Fill(8,buf - BufCopy
- buf points to another buffer. The current buffer gets copied there
Fill(9,buf - BufOR
- buf points to another buffer. This gets copied to the current buffer with OR logic.
Fill(10,buf - BufAND
- buf points to another buffer. This gets copied to the current buffer with AND logic.
Fill(11,buf - BufXOR
- buf points to another buffer. This gets copied to the current buffer with XOR logic.
Fill(12,buf - BufErase
- buf points to another buffer. This gets copied to the current buffer by erasing.
Fill(13,buf - BufSwap
- buf points to a buffer. This swaps the current buffer with the other.
Fill(14,n - CopyDownOR
- The current buffer is copied n pixels down to itself with OR logic
Fill(15,n - CopyDownAND
- The current buffer is copied n pixels down to itself with AND logic
Fill(16,n - CopyDownXOR
- The current buffer is copied n pixels down to itself with XOR logic
Fill(17,n - CopyDownErase
- The current buffer is copied n pixels down to itself with Erase logic
Fill(18,n - CopyUpOR
- The current buffer is copied n pixels up to itself with OR logic
Fill(19,n - CopyUpAND
- The current buffer is copied n pixels up to itself with AND logic
Fill(20,n - CopyUpXOR
- The current buffer is copied n pixels up to itself with XOR logic
Fill(21,n - CopyUpErase
- The current buffer is copied n pixels up to itself with Erase logic
Fill(22,type - FireCycle
- This burns the contents of the screen for one cycle. If type is 0, white fire is used, if it is 1, black fire is used.
Fill(23,Type,Y,X,Width,Height - Fire Cycle 2
- Type is the same as FireCycle and the other inputs are the same as Pt-On( where X and Width go by every 8 pixels.

StorePic

Syntax is: StorePic pic#[,buf, where buf is an optional argument pointing to the buffer to save. By default, buf is the current buffer.

This stores the contents of the buffer to an OS Pic var. This automatically deletes a preexisting picture. You can use this to store to pictures 0 to 255, where 0 = Pic1, 1 = Pic2, 9 = Pic0.

RecallPic

Syntax is: RecallPic pic#[,logic[,buf, where buf is an optional argument pointing to where the contents are copied to. By default, buf is the current buffer.

pic# is the picture var to read from, from 0 to 255 where 0 = Pic1, 1 = Pic2, 9 = Pic0. This works even if the pic var is archived :)

logic is:

0 = Overwrite (default)
1 = AND
2 = XOR
3 = OR
5 = Erase

Rectangles

Unfortunately, you use Line( to draw rectangles. The excuse for this is that when I very first made Grammer 1, I didn't think I'd ever have a line drawing routine, but I had rectangles galore. Without forethought, I decided using the Line( token was quite reasonable. I was wrong.

This is used to draw rectangles. The syntax for this command is: Line(x,y,Height,Width,Method

x is a value from 0 to 95 and is the x pixel coordinate to begin drawing at
y is a value from 0 to 63 and is the y pixel coordinate to begin drawing at
Height is a value from 1 to 64 is the number of pixels tall the box will be
Width is a value from 1 to 96 is the number of pixels tall the box will be
Method is what kind of fill you want:
- 0-White. This turns off all of the pixels of the rectangle
- 1-Black. This turns on all of the pixels of the rectangle
- 2-Invert. This inverts all of the pixels of the rectangle
- 3-Black border. Draws a black perimeter not changing the inside
- 4-White border. Draws a white perimeter not changing the inside
- 5-Inverted border. Draws an inverted perimeter not changing the inside
- 6-Black border, White inside.
- 7-Black border, Inverted inside.
- 8-White border, Black inside.
- 9-White border, Inverted inside.
- 10-Shifts the contents in that rectangle up
- 11-Shifts the contents in that rectangle down
- 12-
- 13-
- 14-Pxl-Test Rect (count the number of ON pixels in the rectangle)
- 15-Pxl-Test Border (count the number of ON pixels on the border)
- 16-Inverted border, black fill
- 17-Inverted border, white fill

Line

This is used to draw lines. The syntax for this command is Line('x1,y1,x2,y2[,Method[,Buffer

So it is two sets of pixel coordinates and then the Method:

0=White
1=Black (Default)
2=Invert

Buffer is the buffer to draw to. It defaults to the current buffer.

Circle

The syntax is Circle(Y,X,R[,Method[,pattern[,buffer. This draws a circle using Y and X as pixel coordinates and R as the radius of the circle in pixels. Method is how to draw the circle:

1 - Black border (Default)
2 - White border
3 - Inverted border
4 - White border, white fill
5 - Black border, black fill
6 - Invert border, invert fill
7 - White border, black fill
8 - White border, invert fill
9 - Black border, white fill
10 - Black border, invert fill
11 - Invert border, white fill
12 - Invert border, black fill

Pattern is a number from 0 to 255 that will be used as a drawing pattern for the border. For example, 85 is 01010101 in binary, so every other pixel will not be drawn. Use 0 for no pattern. If the bit is 0, the pixel will be drawn, if it is 1, it won't be drawn. Buffer is the buffer to draw to (useful with grayscale).

For basic usage:

.0:Return
Circle(32,48,20
DispGraph
Stop

Or an example using a pattern, we need to include the method argument.

.0:Return
Circle(32,48,20,1,85
DispGraph
Stop

Sprites

Pt-Off( is used to draw sprites to pixel coordinates. It is limited in some ways, compared to the Pt-On( command, but more flexible in others. The syntax is: Pt-Off(Method,DataPointer,Y,X,[Width,[Height[,Buffer

Method is how the sprite is drawn:
- 0-Overwrite
- This overwrites the graph screen data this is drawn to.
- 1-AND
- This draws the sprite with AND logic
- 2-XOR
- This draws the sprite with XOR logic
- 3-OR
- This draws the sprite with OR logic
- 5-Erase
- Where there are normally pixels on for the sprite, this draws them as pixels off. *By adding 8 to the Method, the data will be read as hexadecimal
DataPointer is a pointer to the sprite data
Y is the pixel Y-coordinate
X is the pixel X-coordinate
Width is the width of the sprite (in bytes). The default is 1 (8 pixels).
Height is the number of pixels tall the sprite is. 8 is default

Tiles

Pt-On( also draws sprites, but only to 12 columns (every 8 pixels). This is slightly faster than Pt-Off( and has the advantage of variable width. It also has the DataSwap option that isn't present with the Pt-Off( command. Here is the syntax of the command: Pt-On(Method,DataPointer,Y,X,[Width,[Height[,Buffer

Method-This is how the sprite is drawn:
- 0-Overwrite
- 1-AND
- 2-XOR
- 3-OR
- 4-DataSwap
- This swaps the data on the graph screen with the sprite data. Doing this twice results in no change.
- 5-Erase
- 6-Mask
- This will display a masked sprite.
- 7-Gray
- This draws a frame of a 3 level gray sprite *By adding 8 to the Method, the data will be read as hexadecimal
DataPointer is a pointer to the sprite data
Y is the pixel Y-coordinate
X is a value from 0 to 11.
Width is how wide the sprite is. 1=8 pixels, 2=16 pixels,.... Default is 1.
Height is the number of pixels tall the sprite is. Default is 8.

Tilemap

Pt-Change( command is used to draw tilemaps.

Tilemap Method 0

Pt-Change(0,MapData,TileData,MapWidth,MapXOffset,MapYOffset,TileMethod

MapData is a pointer to the map data
TileData is a pointer to the tile set
MapWidth is the width of the map (at least 12)
MapXOffset is the X offset into the map data
MapYOffset is the Y offset into the map data
TileMethod is how the sprite will be drawn (see Pt-On()

Please note that the tile data and map data have to be raw bytes, as opposed to hexadecimal. There are some tools written in Grammer for creating sprite sets and tilemaps on TICalc or Omnimaga.

Smooth Scrolling Tilemap

This is new in version 2.50.9.1.

Init

In order for smooth scrolling to be fast, Grammer needs to pre-compute a bunch of values. You must initialize the tilemap:

TileMap(1,tilemap,sprite_sheet,map_height,map_width[,buffer
  tilemap - points to the tilemap (organized in rows)
  sprite_sheet - points to an array of sprites
  map_height - is the height of the map in tiles
  map_width - is the width of the map in tiles
  buffer - is an optional argument. Defaults to the current buffer.

*NOTE: The tilemap data is set up differently from the original method! This map data is organized in such a way that is compatible with most map editors, so organized by row.*

*NOTE: The buffer argument assigns a buffer for the tilemap and is independent of the default buffer. When you render the tilemap, it ignores what the default buffer is, instead using the assigned tilemap buffer.*

*NOTE: This command does not draw anything! It just sets up pointers. See Full Render to actually draw anything.*

Full Render

After a tilemap is initialized, you'll probably want to draw the starting map. This routine will render the tilemap to the tilemap buffer.

Syntax is TileMap(2[,y[,x. This has an optional y and x argument that refer to the upper-left tile. Default is (0,0). For example, if you want to start 1 row and 1 column into the map data, you could do: TileMap(2,1,1.

Scrolling

Now that you have the map initialized and rendered, you can start scrolling! To scroll, you supply a direction and a number of pixels to scroll by. These routines will scroll the screen, scrolling in the new data. Available commands:

TileMap(3,# - shift down
TileMap(4,# - shift left
TileMap(5,# - shift right
TileMap(6,# - shift up
Tilemap(7,dir,# - shift in a combined direction:
- dir is 1 for down, 2 for left, 4 for right, 8 for up. To shift up+left, you can use a dir of 8+2 = 10.

An easy way to remember the order of the directions is that the follow the order of the getKey codes.

Get Tile, Set Tile

You can read a tile number based on its map coordinates, or set a tile based on its map coordinates. As well, you can get a tile number based on the pixel coordinates on the screen.

TileMap(8,y,x - read a tile
TileMap(9,y,x,# - set a tile to a new value, returns the old value
TileMap(10,y,x - read a tile based on pixel coordinates.

drawing.md 33 KB Historia Raaka

Table of Contents