MetaFun - Pragma ADE

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72 draw fullcircle scaled 100 ; draw fullcircle scaled 100bp ; You might be tempted to omit the unit, but this can be confusing, particularly if you also program in a language like METAFONT, where the pt is the base unit. This means that a circle scaled to 100 in METAPOST is not the same as a circle scaled to 100 in METAFONT. Consider the next definition: pickup pencircle scaled 0 ; fill unitsquare xscaled 400pt yscaled -.5cm withcolor .625red ; fill unitsquare xscaled 400bp yscaled +.5cm withcolor .625yellow ; drawoptions(withcolor white) ; label.rt("400 pt", origin shifted (0, -.25cm)) ; label.rt("400 bp", origin shifted (0, +.25cm)) ; When processed, the difference between a pt and bp shows rather well. Watch how we use .rt to move the label to the right; you can compare this with TEX's macro \rlap. You might want to experiment with .lft, .top, .bot, .ulft, .urt, .llft and .lrt. The difference between both bars is exactly 1.5pt (as calculated by TEX). 400 bp 400 pt Where TEX is anchored in tradition, and therefore more or less uses the pt as the default unit, META POST, much like POSTSCRIPT, has its roots in the computer sciences. There, to simplify calculations, an inch is divided in 72 big points, and .72pt is sacrificed. When you consider that POSTSCRIPT is a high end graphic programming language, you may wonder why this sacrifice was made. Although the difference between 1bp and 1pt is miniscule, this difference is the source of much (unknown) confusion. When TEX users talk about a 10pt font, a desktop publisher hears 10bp. In a similar vein, when we define a papersize having a width of 600pt and a height of 450pt, which is papersize S6 in CONTEXT, a POSTSCRIPT or PDF viewer will report slightly smaller values as page dimensions. This is because those programs claim the pt to be a bp. [This confusion can lead to interesting discussions with desktop publishers when they have to use TEX. They often think that their demand of a baseline distance of 13.4 is met when we set it to 13.4pt, while actually they were thinking of 13.4bp, which of course in other programs is specified using a pt suffix.] Therefore, when embedding graphics in CONTEXT, we strongly recommend that you use pt as the base unit instead. The main reason why we spend so many words on this issue is that, when neglected, large graphics may look inaccurate. Actually, when taken care of, it is one of the (many) reasons why TEX documents always look so accurate. Given that the eye is sensitive to distortions of far less than 1pt, you can be puzzled by the fact that many drawing programs only provide a bounding box in rounded units. Thereby, they round to the next position, to prevent unwanted cropping. For some reason this low resolution has made it into the high end POSTSCRIPT standard. In CONTEXT we try to deal with these issues as well as possible. A few more details Units
2.4 Scaling and shifting When we draw a shape, METAPOST will adapt the bounding box accordingly. This means that a graphic has its natural dimensions, unless of course we adapt the bounding box manually. When you limit your graphic to a simple shape, say a rectangle, shifting it to some place can get obscured by this fact. Therefore, the following series of shapes appear to be the same. draw unitsquare xscaled 6cm yscaled 1.5cm withpen pencircle scaled 2mm withcolor .625red ; draw unitsquare shifted (.5,.5) xscaled 6cm yscaled 1.5cm withpen pencircle scaled 2mm withcolor .625red ; draw unitsquare shifted (-.5,-.5) xscaled 6cm yscaled 1.5cm withpen pencircle scaled 2mm withcolor .625red ; draw unitsquare xscaled 6cm yscaled 1.5cm shifted (1cm,1cm) withpen pencircle scaled 2mm withcolor .625red ; draw unitsquare xscaled 6cm yscaled 1.5cm shifted (1.5cm,1cm) withpen pencircle scaled 2mm withcolor .625red ; Scaling and shifting A few more details 73
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Hans Hagen metafun context mkiv
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Introduction This document is about
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Content Conventions . . . . . . . .
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1 Conventions When reading this man
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1 Welcome to MetaPost 1.1 Paths 2 I
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The open path is defined as: (1cm,1
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1.2 Transformations We can store a
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(x,y) zscaled (u,v) (xu − yv,xv +
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z0 = (0.5cm,1.5cm) ; z1 = (2.5cm,2.
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4 0 1 3 2 "z0..z1..z2..z3..z0" Only
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0 1 3 2 "z0..z1..z2--z3" Watch how
Page 25 and 26: 0 1 0 2 2 1 "(z0..z1..z2..z3) cutaf
Page 27 and 28: 2 0 1 Using ( ) is not mandatory bu
Page 29 and 30: 0 4 1 3 2 0 These two graphics were
Page 31 and 32: Since we don't consider this unfill
Page 33 and 34: First there is the concept of varia
Page 35 and 36: 1.8 Loops Yet another programming c
Page 37 and 38: If in the definition of doublescale
Page 39 and 40: test (a) (b) (c) (d) ; test (a,b) (
Page 41 and 42: If you forget about the colors, the
Page 43 and 44: linejoin=mitered linecap=butt linej
Page 45 and 46: 1.15 Text Most dashpatterns can be
Page 47 and 48: Z13 Z24 Z14 Z1 Z12 Z2 Z21 Z23 Z11 Z
Page 49 and 50: 3 Because we want to call this macr
Page 51 and 52: dotlabel.rt ("$Z_{3}$", z3) ; dotla
Page 53 and 54: A different approach is to use a tw
Page 55 and 56: The graphic extends beyond the boun
Page 57 and 58: p := (p shifted (5cm,0)) randomized
Page 59 and 60: path p ; p := (0,0) -- (2cm,3cm) ;
Page 61 and 62: path p ; p := (0cm,0cm) -- (4cm,1cm
Page 63 and 64: Here, the image macro creates an (a
Page 65 and 66: So, in addition to on to specify a
Page 67 and 68: Watch how we can pass a point (poin
Page 69 and 70: 2 A few more details In this chapte
Page 71 and 72: The second line does just as it say
Page 73 and 74: fill shape ; draw shape ; filldraw
Page 75: 2.3 Units 6 As you can see here, as
Page 79 and 80: Especially when a path results from
Page 81 and 82: points first order curve second ord
Page 83 and 84: first iteration second iteration th
Page 85 and 86: and get: We don't even need that mu
Page 87 and 88: Figure 2.3 Circles with minimized i
Page 89 and 90: The tension specifier can be used t
Page 91 and 92: The asymetrical tensions are less p
Page 93 and 94: z0 .. z1 .. z2 z0 {curl 1} .. z1 ..
Page 95 and 96: 7 In literature concerning POSTSCRI
Page 97 and 98: currentpicture := currentpicture sl
Page 99 and 100: We can achieve this by defining poi
Page 101 and 102: We're still not there. Like in a pr
Page 103 and 104: Due to the thicker line width used
Page 105 and 106: left up down right The previous def
Page 107 and 108: Here the & glues strings together,
Page 109 and 110: picture p ; p := "MetaFun" normalin
Page 111 and 112: pickup pencircle scaled 2pt ; draw
Page 113 and 114: Because the z--variables are used f
Page 115 and 116: 3 Embedded graphics In addition to
Page 117 and 118: \startMPcode fill fullcircle scaled
Page 119 and 120: \startuniqueMPgraphic{right or wron
Page 121 and 122: {\externalfigure[mprun:extrafun::my
Page 123 and 124: \startlinecorrection[blank] \proces
Page 125 and 126: In order to prevent problems, we ad
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There are a few more low level swit
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When we convert color to gray, we u
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4 Enhancing the layout One of the m
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4.2 Overlay variables [offset=3pt,f
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This background demonstrates that a
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As you may know, TEX's ambassador i
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This works as expected: \RotatedTex
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We will now apply this knowledge of
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p := p shifted (2o,OverlayHeight-yp
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We demonstrated that when defining
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5 Positional graphics In this chapt
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5.2 Anchors and layers In a previou
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pab := pab cutafter (pab intersecti
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fill p withcolor \MPcolor{lightgray
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The previous example also demonstra
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\setMPlayer [test] [somepos-1] [loc
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6 Page backgrounds Especially in in
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As soon as you want to make an elec
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do_it (1,4,false) ; do_it (5,4,fals
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gigigi Watch how the bounding boxes
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You can test this concept yourself
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StartPage ; fill Area[Text][Text] s
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fi ; Main := Main enlarged 6pt ; pi
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ulcorner Field[Text] [Text] -urcorn
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The left picture demonstrates what
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There are two more operators: inner
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7 Shapes, symbols and buttons One c
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Table 7.1 demonstrates how scratch
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for i := 1 upto \MPvar{n} : xpos :=
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This table is defined as: \bTABLE[f
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Since we have collected some nice b
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8 Special effects Sometimes we want
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Because of this implementation, sha
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test_shade(origin shifted (.25cm,0)
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fill p shifted (3cm,0) withcolor .5
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\definecolor [tred] [r=1,t=.5,a=exc
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Figure 8.4 Another clipped cow. \pl
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withpen pencircle scaled 4mm withco
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Because this graphic is the result
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The resulting PDF file can be inclu
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Including another METAPOST graphic,
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After these examples your are proba
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In this graphic, we have two text f
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} {}} Here we feed some MATHML int
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9 Functions METAPOST provides a wid
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9.2 Grids Some day you may want to
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13 13 13 13 Figure 9.1 Quick and di
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2 − ×10 1 − 1 0×100 Figure 9.
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Figure 9.3 By using transparent col
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There are enough applications out t
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Of course we could extend this LUA
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10 Typesetting in METAPOST It is sa
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Meta is a female lion! Figure 10.2
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We use the low level CONTEXT macro
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So, now we have: M etaPostisFun! Wh
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n := n + 1 ; len[n] := \the\wd\MPbo
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ap := point at of RotPath ; ad := d
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\startoverlay {\startuseMPgraphic{f
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\startuseMPgraphic{text draw} draw
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vsize := ypart urcorner p - ypart l
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We are now ready for an attempt to
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We can manipulate the heigth and de
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\strutheight) ; % height of first l
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w := h := 6cm ; o := 6pt ; path p ;
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Donald Knuth has spent the past sev
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Donald Knuth has spent the past sev
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11 Debugging Those familiar with CO
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4 3 5 2 6 1 0 7 8 You can pass opti
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3 4 0 2 1 Of course you may want to
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12 Defining styles Since the integr
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color=gray, contrastcolor=gray, sty
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def right_menu_button (expr nn, rr,
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\Topic {Edward R. Tufte} \input tuf
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A Few Nice Quotes A Simple Style De
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13 A few applications For those who
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vardef spring (expr a, b, w, h, n)
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There is a numeric constant labelof
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text text text text text text text
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p := fullcircle scaled (2*length(lo
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These definitions of anglebetween a
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Because in most cases we want the l
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γ δ β ɛ α ζ δ γ β ɛ metho
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There are for sure more (efficient)
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The next circle that we draw shows
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popcurrentpicture ; enddef ; Here,
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draw (u,i) -- (2u,i) withcolor .5wh
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Figure 13.4 Koffka's examples of ma
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\startbuffer[a] def start_everythin
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pointC := circleA intersectionpoint
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draw_basics ; draw_circles ; draw_i
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Figure 13.6 Bisecting a line segmen
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z1 = (0, height/2) ; z2 = (width/2-
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The clipping path is applied by say
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13.8 Music sheets The next example
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The euro symbol A few applications
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draw i withpen pencircle scaled 1pt
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16 draw b withpen pencircle scaled
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\startMPcode \includeMPgraphic{gamb
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14 METAFUN macros CONTEXT comes wit
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A METAPOST syntax In the METAFONT b
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〈number or fraction〉 → 〈num
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〈suffix〉 → 〈empty〉 | 〈s
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〈assignment〉 → 〈variable〉
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〈command〉 → clip 〈picture v
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〈if test〉 → if 〈boolean exp
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B This document This document is pr
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C Reference C.1 Paths In this chapt
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tension atleast numeric (0,0)..(.75
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angle origin--dir(angle(1,1)) metap
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circle bcircle metafun variable lci
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path randomized numeric/pair unitsq
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path stretched numeric/pair (fullci
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path zscaled pair fullcircle zscale
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path llenlarged numeric fullcircle
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path urmoved numeric fullcircle urm
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everse path reverse fullcircle shif
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oundingbox path boundingbox fullcir
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C.3 Points top pair top center full
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C.4 Attributes withcolor rgbcolor w
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draw draw fullcircle metapost macro
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ounded linecap := rounded metapost
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label.top label.top("MetaFun",origi
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D Literature There is undoubtly mor
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Index a anchoring 143, 145 angles 2
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This document introduces you in the
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