author Wuzzy Thu, 03 May 2018 00:44:13 +0100 changeset 1388 23cc8581c0da parent 743 d22bb25c55ac child 1389 b57ad8939f32 permissions -rw-r--r--
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#summary Drawing maps with Lua.

= Drawing maps with Lua (OUTDATED) =

== Overview ==
Starting in 0.9.18 it is possible to reliably use drawn map mode to draw maps with scripts.
A simple example is given below.  Note that Drawn maps use an area of 4096Ă—2048. The examples below are static, but obviously this could be used for a random map variationâ€”for example, simulating the Cave map by doing the fill below, then drawing random tunnels using circles that shift their course smoothly.

== Details ==
First, a couple of convenience functions for drawing to the map.
<code lang="lua">
PointsBuffer = ''  -- A string to accumulate points in
PointsBuffer = PointsBuffer .. string.char(band(x,0xff00) / 256 , band(x,0xff) , band(y,0xff00) / 256 , band(y,0xff))
if width then
width = bor(width,0x80)
if erase then
width = bor(width,0x40)
end
PointsBuffer = PointsBuffer .. string.char(width)
else
PointsBuffer = PointsBuffer .. string.char(0)
end
if #PointsBuffer > 245 then
ParseCommand('draw '..PointsBuffer)
PointsBuffer = ''
end
end
function FlushPoints()
if #PointsBuffer > 0 then
ParseCommand('draw '..PointsBuffer)
PointsBuffer = ''
end
end
</code>
`AddPoint` takes an x and y location for the point, a width (indicates the start of a new line) and `erase` (whether the line is erasing from the map). The width calculation is described in [DrawnMapFormat].

`FlushPoints` writes out any values from `PointsBuffer` that have not already been sent to the engine.
It would be called at the end of a drawing session.

A simple example below.

<code lang="lua">
function onGameInit()
MapGen = 2
TemplateFilter = 0

for i = 63,2,-4 do
end

for i = 1,2000,50 do
end

FlushPoints()
end
</code>
The first set of `AddPoint`s draws a large X and erases the centre.
The following loop draws a set of nested points, alternating erasure and fill, which results in a set of concentric circles.
The 2nd loop draws a web of lines and frames it using some final `AddPoint`s.

<a href="http://m8y.org/hw/draw1.jpeg">screenshot here</a>

Another brief example:
<code lang="lua">
for i = 200,2000,600 do