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diff --git a/doc/context/sources/general/manuals/luametafun/luametafun-shade.tex b/doc/context/sources/general/manuals/luametafun/luametafun-shade.tex new file mode 100644 index 000000000..a139be954 --- /dev/null +++ b/doc/context/sources/general/manuals/luametafun/luametafun-shade.tex @@ -0,0 +1,230 @@ +% language=us + +\environment luametafun-style + +\startcomponent luametafun-shade + +\startchapter[title={Shade}] + +{\em This interface is still experimental!} + +Shading is complex. We go from one color to another on a continuum either linear +or circular. We have to make sure that we cover the whole shape and that means +that we have to guess a little, although one can influence this with parameters. +It can involve a bit of trial and error, which is more complex that using a +graphical user interface but this is the price we pay. It goes like this: + +\startbuffer[1] +\startMPcode +definecolor [ name = "MyColor3", r = 0.22, g = 0.44, b = 0.66 ] ; +definecolor [ name = "MyColor4", r = 0.66, g = 0.44, b = 0.22 ] ; + +draw lmt_shade [ + path = fullcircle scaled 4cm, + direction = "right", + domain = { 0, 2 }, + colors = { "MyColor3", "MyColor4" }, +] ; + +draw lmt_shade [ + path = fullcircle scaled 3cm, + direction = "left", + domain = { 0, 2 }, + colors = { "MyColor3", "MyColor4" }, +] shifted (45mm,0) ; + +draw lmt_shade [ + path = fullcircle scaled 5cm, + direction = "up", + domain = { 0, 2 }, + colors = { "MyColor3", "MyColor4" }, +] shifted (95mm,0) ; + +draw lmt_shade [ + path = fullcircle scaled 1cm, + direction = "down", + domain = { 0, 2 }, + colors = { "MyColor3", "MyColor4" }, +] shifted (135mm,0) ; +\stopMPcode +\stopbuffer + +\typebuffer[1][option=TEX] + +Normally this is good enough as demonstrated in \in {figure} [shade:1] because +we use shades as backgrounds. In the case of a circular shade we need to tweak +the domain because guessing doesn't work well. + +\startplacefigure[reference=shade:1,title={Simple circular shades.}] + \getbuffer[1] +\stopplacefigure + +\startbuffer[2] +\startMPcode +draw lmt_shade [ + path = fullsquare scaled 4cm, + alternative = "linear", + direction = "right", + colors = { "MyColor3", "MyColor4" }, +] ; + +draw lmt_shade [ + path = fullsquare scaled 3cm, + direction = "left", + alternative = "linear", + colors = { "MyColor3", "MyColor4" }, +] shifted (45mm,0) ; + +draw lmt_shade [ + path = fullsquare scaled 5cm, + direction = "up", + alternative = "linear", + colors = { "MyColor3", "MyColor4" }, +] shifted (95mm,0) ; + +draw lmt_shade [ + path = fullsquare scaled 1cm, + direction = "down", + alternative = "linear", + colors = { "MyColor3", "MyColor4" }, +] shifted (135mm,0) ; +\stopMPcode +\stopbuffer + +\typebuffer[2][option=TEX] + +\startplacefigure[reference=shade:2,title={Simple rectangular shades.}] + \getbuffer[2] +\stopplacefigure + +The \type {direction} relates to the boundingbox. Instead of a keyword you can +also give two values, indicating points on the boundingbox. Because a boundingbox +has four points, the \type {up} direction is equivalent to \type {{0.5,2.5}}. + +The parameters \type {center}, \type {factor}, \type {vector} and \type {domain} +are a bit confusing but at some point the way they were implemented made sense, +so we keep them as they are. The center moves the center of the path that is used +as anchor for one color proportionally to the bounding box: the given factor is +multiplied by half the width and height. + +\startbuffer[3] +\startMPcode +draw lmt_shade [ + path = fullcircle scaled 5cm, + domain = { .2, 1.6 }, + center = { 1/10, 1/10 }, + direction = "right", + colors = { "MyColor3", "MyColor4" }, + trace = true, +] ; +\stopMPcode +\stopbuffer + +\typebuffer[3][option=TEX] + +\startplacefigure[reference=shade:3,title={Moving the centers.}] + \getbuffer[3] +\stopplacefigure + +A vector takes the given points on the path as centers for the colors, see \in +{figure} [shade:4]. + +\startbuffer[4] +\startMPcode +draw lmt_shade [ + path = fullcircle scaled 5cm, + domain = { .2, 1.6 }, + vector = { 2, 4 }, + direction = "right", + colors = { "MyColor3", "MyColor4" }, + trace = true, +] ; +\stopMPcode +\stopbuffer + +\typebuffer[4][option=TEX] + +\startplacefigure[reference=shade:4,title={Using a vector (points).}] + \getbuffer[4] +\stopplacefigure + +Messing with the radius in combination with the previously mentioned domain +is really trial and error, as seen in \in {figure} [shade:5]. + +\startbuffer[5] +\startMPcode +draw lmt_shade [ + path = fullcircle scaled 5cm, + domain = { 0.5, 2.5 }, + radius = { 2cm, 6cm }, + direction = "right", + colors = { "MyColor3", "MyColor4" }, + trace = true, +] ; +\stopMPcode +\stopbuffer + +\typebuffer[5][option=TEX] + +\startplacefigure[reference=shade:5,title={Tweaking the radius.}] + \getbuffer[5] +\stopplacefigure + +But actually the radius used alone works quite well as shown in \in {figure} +[shade:6]. + +\startbuffer[6] +\startMPcode +draw lmt_shade [ + path = fullcircle scaled 5cm, + colors = { "red", "green" }, + trace = true, +] ; + +draw lmt_shade [ + path = fullcircle scaled 5cm, + colors = { "red", "green" }, + radius = 2.5cm, + trace = true, +] shifted (6cm,0) ; + +draw lmt_shade [ + path = fullcircle scaled 5cm, + colors = { "red", "green" }, + radius = 2.0cm, + trace = true, +] shifted (12cm,0) ; +\stopMPcode +\stopbuffer + +\typebuffer[6][option=TEX] + +\startplacefigure[reference=shade:6,title={Just using the radius.}] + \getbuffer[6] +\stopplacefigure + +\starttabulate[|T|T|T|p|] +\FL +\BC name \BC type \BC default \BC comment \NC \NR +\ML +\NC alternative \NC string \NC circular \NC or \type {linear} \NC \NR +\NC path \NC path \NC \NC \NC \NR +\NC trace \NC boolean \NC false \NC \NC \NR +\NC domain \NC set of numerics \NC \NC \NC \NR +\NC radius \NC numeric \NC \NC \NC \NR +\NC \NC set of numerics \NC \NC \NC \NR +\NC factor \NC numeric \NC \NC \NC \NR +\NC origin \NC pair \NC \NC \NC \NR +\NC \NC set of pairs \NC \NC \NC \NR +\NC vector \NC set of numerics \NC \NC \NC \NR +\NC colors \NC set of strings \NC \NC \NC \NR +\NC center \NC numeric \NC \NC \NC \NR +\NC \NC set of numerics \NC \NC \NC \NR +\NC direction \NC string \NC \NC \type{up}, \type {down}, \type {left}, \type {right} \NC \NR +\NC \NC set of numerics \NC \NC two points on the boundingbox \NC \NR +\LL +\stoptabulate + +\stopchapter + +\stopcomponent |