1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
|
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Mu - apps/mandelbrot.mu</title>
<meta name="Generator" content="Vim/8.2">
<meta name="plugin-version" content="vim8.1_v2">
<meta name="syntax" content="none">
<meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy=,use_input_for_pc=fallback">
<meta name="colorscheme" content="minimal-light">
<style>
<!--
pre { white-space: pre-wrap; font-family: monospace; color: #000000; background-color: #ffffd7; }
body { font-size:12pt; font-family: monospace; color: #000000; background-color: #ffffd7; }
a { color:inherit; }
* { font-size:12pt; font-size: 1em; }
.PreProc { color: #c000c0; }
.muRegEbx { color: #5f00ff; }
.muRegEcx { color: #870000; }
.muRegEdx { color: #af5f00; }
.LineNr { }
.muRegEsi { color: #005faf; }
.muRegEdi { color: #00af00; }
.Constant { color: #008787; }
.muFunction { color: #af5f00; text-decoration: underline; }
.Delimiter { color: #c000c0; }
.muComment { color: #005faf; }
.Special { color: #ff6060; }
-->
</style>
<script>
<!--
/* function to open any folds containing a jumped-to line before jumping to it */
function JumpToLine()
{
var lineNum;
lineNum = window.location.hash;
lineNum = lineNum.substr(1); /* strip off '#' */
if (lineNum.indexOf('L') == -1) {
lineNum = 'L'+lineNum;
}
var lineElem = document.getElementById(lineNum);
/* Always jump to new location even if the line was hidden inside a fold, or
* we corrected the raw number to a line ID.
*/
if (lineElem) {
lineElem.scrollIntoView(true);
}
return true;
}
if ('onhashchange' in window) {
window.onhashchange = JumpToLine;
}
-->
</script>
</head>
<body onload='JumpToLine();'>
<a href='https://github.com/akkartik/mu/blob/main/apps/mandelbrot.mu'>https://github.com/akkartik/mu/blob/main/apps/mandelbrot.mu</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="muComment"># Mandelbrot set</span>
<span id="L2" class="LineNr"> 2 </span><span class="muComment">#</span>
<span id="L3" class="LineNr"> 3 </span><span class="muComment"># Install:</span>
<span id="L4" class="LineNr"> 4 </span><span class="muComment"># $ git clone <a href="https://github.com/akkartik/mu">https://github.com/akkartik/mu</a></span>
<span id="L5" class="LineNr"> 5 </span><span class="muComment"># $ cd mu</span>
<span id="L6" class="LineNr"> 6 </span><span class="muComment"># Build on Linux:</span>
<span id="L7" class="LineNr"> 7 </span><span class="muComment"># $ ./translate apps/mandelbrot.mu</span>
<span id="L8" class="LineNr"> 8 </span><span class="muComment"># Build on other platforms (slow):</span>
<span id="L9" class="LineNr"> 9 </span><span class="muComment"># $ ./translate_emulated apps/mandelbrot.mu</span>
<span id="L10" class="LineNr"> 10 </span><span class="muComment"># Run:</span>
<span id="L11" class="LineNr"> 11 </span><span class="muComment"># $ qemu-system-i386 code.img</span>
<span id="L12" class="LineNr"> 12 </span>
<span id="L13" class="LineNr"> 13 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='mandelbrot.mu.html#L13'>main</a></span> <a href='../500fake-screen.mu.html#L14'>screen</a>: (addr <a href='../500fake-screen.mu.html#L14'>screen</a>), keyboard: (addr keyboard), data-disk: (addr disk) <span class="Delimiter">{</span>
<span id="L14" class="LineNr"> 14 </span> <span class="muComment"># Initially the viewport is centered at 0, 0 in the scene.</span>
<span id="L15" class="LineNr"> 15 </span> <span class="PreProc">var</span> zero: float
<span id="L16" class="LineNr"> 16 </span> <span class="PreProc">var</span> scene-cx/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> copy zero
<span id="L17" class="LineNr"> 17 </span> <span class="PreProc">var</span> scene-cy/<span class="Constant">xmm2</span>: float <span class="Special"><-</span> copy zero
<span id="L18" class="LineNr"> 18 </span> <span class="muComment"># Initially the viewport shows a section of the scene 4 units wide.</span>
<span id="L19" class="LineNr"> 19 </span> <span class="muComment"># scene-width-scale = 0.5</span>
<span id="L20" class="LineNr"> 20 </span> <span class="PreProc">var</span> scene-width-scale: float
<span id="L21" class="LineNr"> 21 </span> <span class="PreProc">var</span> dest/eax: (addr float) <span class="Special"><-</span> address scene-width-scale
<span id="L22" class="LineNr"> 22 </span> <a href='../408float.mu.html#L3'>fill-in-rational</a> dest, <span class="Constant">1</span>, <span class="Constant">2</span>
<span id="L23" class="LineNr"> 23 </span> <span class="muComment"># scene-width = 4</span>
<span id="L24" class="LineNr"> 24 </span> <span class="PreProc">var</span> four: float
<span id="L25" class="LineNr"> 25 </span> <span class="PreProc">var</span> dest/eax: (addr float) <span class="Special"><-</span> address four
<span id="L26" class="LineNr"> 26 </span> <a href='../408float.mu.html#L3'>fill-in-rational</a> dest, <span class="Constant">4</span>, <span class="Constant">1</span>
<span id="L27" class="LineNr"> 27 </span> <span class="PreProc">var</span> scene-width/<span class="Constant">xmm3</span>: float <span class="Special"><-</span> copy four
<span id="L28" class="LineNr"> 28 </span> <span class="Delimiter">{</span>
<span id="L29" class="LineNr"> 29 </span> <a href='mandelbrot.mu.html#L41'>mandelbrot</a> <a href='../500fake-screen.mu.html#L14'>screen</a> scene-cx, scene-cy, scene-width
<span id="L30" class="LineNr"> 30 </span> <span class="muComment"># move the center some % of the current screen-width</span>
<span id="L31" class="LineNr"> 31 </span> <span class="PreProc">var</span> adj/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> <a href='../408float.mu.html#L18'>rational</a> <span class="Constant">2</span>, <span class="Constant">0x1c</span>/<span class="Constant">28</span>
<span id="L32" class="LineNr"> 32 </span> adj <span class="Special"><-</span> multiply scene-width
<span id="L33" class="LineNr"> 33 </span> scene-cx <span class="Special"><-</span> subtract adj
<span id="L34" class="LineNr"> 34 </span> scene-cy <span class="Special"><-</span> add adj
<span id="L35" class="LineNr"> 35 </span> <span class="muComment"># slowly shrink the scene width to zoom in</span>
<span id="L36" class="LineNr"> 36 </span> scene-width <span class="Special"><-</span> multiply scene-width-scale
<span id="L37" class="LineNr"> 37 </span> <span class="PreProc">loop</span>
<span id="L38" class="LineNr"> 38 </span> <span class="Delimiter">}</span>
<span id="L39" class="LineNr"> 39 </span><span class="Delimiter">}</span>
<span id="L40" class="LineNr"> 40 </span>
<span id="L41" class="LineNr"> 41 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='mandelbrot.mu.html#L41'>mandelbrot</a></span> <a href='../500fake-screen.mu.html#L14'>screen</a>: (addr <a href='../500fake-screen.mu.html#L14'>screen</a>), scene-cx: float, scene-cy: float, scene-width: float <span class="Delimiter">{</span>
<span id="L42" class="LineNr"> 42 </span> <span class="PreProc">var</span> a/eax: int <span class="Special"><-</span> copy <span class="Constant">0</span>
<span id="L43" class="LineNr"> 43 </span> <span class="PreProc">var</span> b/<span class="muRegEcx">ecx</span>: int <span class="Special"><-</span> copy <span class="Constant">0</span>
<span id="L44" class="LineNr"> 44 </span> a, b <span class="Special"><-</span> <a href='../500fake-screen.mu.html#L86'>screen-size</a> <a href='../500fake-screen.mu.html#L14'>screen</a>
<span id="L45" class="LineNr"> 45 </span> <span class="PreProc">var</span> width/<span class="muRegEsi">esi</span>: int <span class="Special"><-</span> copy a
<span id="L46" class="LineNr"> 46 </span> width <span class="Special"><-</span> shift-left <span class="Constant">3</span>/log2-font-width
<span id="L47" class="LineNr"> 47 </span> <span class="PreProc">var</span> height/<span class="muRegEdi">edi</span>: int <span class="Special"><-</span> copy b
<span id="L48" class="LineNr"> 48 </span> height <span class="Special"><-</span> shift-left <span class="Constant">4</span>/log2-font-height
<span id="L49" class="LineNr"> 49 </span> <span class="PreProc">var</span> y/<span class="muRegEcx">ecx</span>: int <span class="Special"><-</span> copy <span class="Constant">0</span>
<span id="L50" class="LineNr"> 50 </span> <span class="Delimiter">{</span>
<span id="L51" class="LineNr"> 51 </span> compare y, height
<span id="L52" class="LineNr"> 52 </span> <span class="PreProc">break-if->=</span>
<span id="L53" class="LineNr"> 53 </span> <span class="PreProc">var</span> imaginary/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> <a href='mandelbrot.mu.html#L157'>viewport-to-imaginary</a> y, width, height, scene-cy, scene-width
<span id="L54" class="LineNr"> 54 </span> <span class="PreProc">var</span> x/<span class="muRegEbx">ebx</span>: int <span class="Special"><-</span> copy <span class="Constant">0</span>
<span id="L55" class="LineNr"> 55 </span> <span class="Delimiter">{</span>
<span id="L56" class="LineNr"> 56 </span> compare x, width
<span id="L57" class="LineNr"> 57 </span> <span class="PreProc">break-if->=</span>
<span id="L58" class="LineNr"> 58 </span> <span class="PreProc">var</span> real/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> <a href='mandelbrot.mu.html#L138'>viewport-to-real</a> x, width, scene-cx, scene-width
<span id="L59" class="LineNr"> 59 </span> <span class="PreProc">var</span> iterations/eax: int <span class="Special"><-</span> <a href='mandelbrot.mu.html#L73'>mandelbrot-iterations-for-point</a> real, imaginary, <span class="Constant">0x400</span>/max
<span id="L60" class="LineNr"> 60 </span> iterations <span class="Special"><-</span> shift-right <span class="Constant">3</span>
<span id="L61" class="LineNr"> 61 </span> <span class="PreProc">var</span> color/<span class="muRegEdx">edx</span>: int <span class="Special"><-</span> copy <span class="Constant">0</span>
<span id="L62" class="LineNr"> 62 </span> iterations, color <span class="Special"><-</span> <a href='../314divide.subx.html#L3'>integer-divide</a> iterations, <span class="Constant">0x18</span>/<span class="Constant">24</span>/size-of-cycle-0
<span id="L63" class="LineNr"> 63 </span> color <span class="Special"><-</span> add <span class="Constant">0x20</span>/cycle-0
<span id="L64" class="LineNr"> 64 </span> <a href='../500fake-screen.mu.html#L483'>pixel</a> <a href='../500fake-screen.mu.html#L14'>screen</a>, x, y, color
<span id="L65" class="LineNr"> 65 </span> x <span class="Special"><-</span> increment
<span id="L66" class="LineNr"> 66 </span> <span class="PreProc">loop</span>
<span id="L67" class="LineNr"> 67 </span> <span class="Delimiter">}</span>
<span id="L68" class="LineNr"> 68 </span> y <span class="Special"><-</span> increment
<span id="L69" class="LineNr"> 69 </span> <span class="PreProc">loop</span>
<span id="L70" class="LineNr"> 70 </span> <span class="Delimiter">}</span>
<span id="L71" class="LineNr"> 71 </span><span class="Delimiter">}</span>
<span id="L72" class="LineNr"> 72 </span>
<span id="L73" class="LineNr"> 73 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='mandelbrot.mu.html#L73'>mandelbrot-iterations-for-point</a></span> real: float, imaginary: float, max: int<span class="PreProc"> -> </span>_/eax: int <span class="Delimiter">{</span>
<span id="L74" class="LineNr"> 74 </span> <span class="PreProc">var</span> zero: float
<span id="L75" class="LineNr"> 75 </span> <span class="PreProc">var</span> x/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> copy zero
<span id="L76" class="LineNr"> 76 </span> <span class="PreProc">var</span> y/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> copy zero
<span id="L77" class="LineNr"> 77 </span> <span class="PreProc">var</span> iterations/<span class="muRegEcx">ecx</span>: int <span class="Special"><-</span> copy <span class="Constant">0</span>
<span id="L78" class="LineNr"> 78 </span> <span class="Delimiter">{</span>
<span id="L79" class="LineNr"> 79 </span> <span class="PreProc">var</span> done?/eax: boolean <span class="Special"><-</span> <a href='mandelbrot.mu.html#L94'>mandelbrot-done?</a> x, y
<span id="L80" class="LineNr"> 80 </span> compare done?, <span class="Constant">0</span>/false
<span id="L81" class="LineNr"> 81 </span> <span class="PreProc">break-if-!=</span>
<span id="L82" class="LineNr"> 82 </span> compare iterations, max
<span id="L83" class="LineNr"> 83 </span> <span class="PreProc">break-if->=</span>
<span id="L84" class="LineNr"> 84 </span> <span class="PreProc">var</span> newx/<span class="Constant">xmm2</span>: float <span class="Special"><-</span> <a href='mandelbrot.mu.html#L112'>mandelbrot-x</a> x, y, real
<span id="L85" class="LineNr"> 85 </span> <span class="PreProc">var</span> newy/<span class="Constant">xmm3</span>: float <span class="Special"><-</span> <a href='mandelbrot.mu.html#L124'>mandelbrot-y</a> x, y, imaginary
<span id="L86" class="LineNr"> 86 </span> x <span class="Special"><-</span> copy newx
<span id="L87" class="LineNr"> 87 </span> y <span class="Special"><-</span> copy newy
<span id="L88" class="LineNr"> 88 </span> iterations <span class="Special"><-</span> increment
<span id="L89" class="LineNr"> 89 </span> <span class="PreProc">loop</span>
<span id="L90" class="LineNr"> 90 </span> <span class="Delimiter">}</span>
<span id="L91" class="LineNr"> 91 </span> <span class="PreProc">return</span> iterations
<span id="L92" class="LineNr"> 92 </span><span class="Delimiter">}</span>
<span id="L93" class="LineNr"> 93 </span>
<span id="L94" class="LineNr"> 94 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='mandelbrot.mu.html#L94'>mandelbrot-done?</a></span> x: float, y: float<span class="PreProc"> -> </span>_/eax: boolean <span class="Delimiter">{</span>
<span id="L95" class="LineNr"> 95 </span> <span class="muComment"># x*x + y*y > 4</span>
<span id="L96" class="LineNr"> 96 </span> <span class="PreProc">var</span> x2/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> copy x
<span id="L97" class="LineNr"> 97 </span> x2 <span class="Special"><-</span> multiply x
<span id="L98" class="LineNr"> 98 </span> <span class="PreProc">var</span> y2/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> copy y
<span id="L99" class="LineNr"> 99 </span> y2 <span class="Special"><-</span> multiply y
<span id="L100" class="LineNr">100 </span> <span class="PreProc">var</span> sum/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> copy x2
<span id="L101" class="LineNr">101 </span> sum <span class="Special"><-</span> add y2
<span id="L102" class="LineNr">102 </span> <span class="PreProc">var</span> four/eax: int <span class="Special"><-</span> copy <span class="Constant">4</span>
<span id="L103" class="LineNr">103 </span> <span class="PreProc">var</span> four-f/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> convert four
<span id="L104" class="LineNr">104 </span> compare sum, four-f
<span id="L105" class="LineNr">105 </span> <span class="Delimiter">{</span>
<span id="L106" class="LineNr">106 </span> <span class="PreProc">break-if-float></span>
<span id="L107" class="LineNr">107 </span> <span class="PreProc">return</span> <span class="Constant">0</span>/false
<span id="L108" class="LineNr">108 </span> <span class="Delimiter">}</span>
<span id="L109" class="LineNr">109 </span> <span class="PreProc">return</span> <span class="Constant">1</span>/true
<span id="L110" class="LineNr">110 </span><span class="Delimiter">}</span>
<span id="L111" class="LineNr">111 </span>
<span id="L112" class="LineNr">112 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='mandelbrot.mu.html#L112'>mandelbrot-x</a></span> x: float, y: float, real: float<span class="PreProc"> -> </span>_/<span class="Constant">xmm2</span>: float <span class="Delimiter">{</span>
<span id="L113" class="LineNr">113 </span> <span class="muComment"># x*x - y*y + real</span>
<span id="L114" class="LineNr">114 </span> <span class="PreProc">var</span> x2/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> copy x
<span id="L115" class="LineNr">115 </span> x2 <span class="Special"><-</span> multiply x
<span id="L116" class="LineNr">116 </span> <span class="PreProc">var</span> y2/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> copy y
<span id="L117" class="LineNr">117 </span> y2 <span class="Special"><-</span> multiply y
<span id="L118" class="LineNr">118 </span> <span class="PreProc">var</span> result/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> copy x2
<span id="L119" class="LineNr">119 </span> result <span class="Special"><-</span> subtract y2
<span id="L120" class="LineNr">120 </span> result <span class="Special"><-</span> add real
<span id="L121" class="LineNr">121 </span> <span class="PreProc">return</span> result
<span id="L122" class="LineNr">122 </span><span class="Delimiter">}</span>
<span id="L123" class="LineNr">123 </span>
<span id="L124" class="LineNr">124 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='mandelbrot.mu.html#L124'>mandelbrot-y</a></span> x: float, y: float, imaginary: float<span class="PreProc"> -> </span>_/<span class="Constant">xmm3</span>: float <span class="Delimiter">{</span>
<span id="L125" class="LineNr">125 </span> <span class="muComment"># 2*x*y + imaginary</span>
<span id="L126" class="LineNr">126 </span> <span class="PreProc">var</span> two/eax: int <span class="Special"><-</span> copy <span class="Constant">2</span>
<span id="L127" class="LineNr">127 </span> <span class="PreProc">var</span> result/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> convert two
<span id="L128" class="LineNr">128 </span> result <span class="Special"><-</span> multiply x
<span id="L129" class="LineNr">129 </span> result <span class="Special"><-</span> multiply y
<span id="L130" class="LineNr">130 </span> result <span class="Special"><-</span> add imaginary
<span id="L131" class="LineNr">131 </span> <span class="PreProc">return</span> result
<span id="L132" class="LineNr">132 </span><span class="Delimiter">}</span>
<span id="L133" class="LineNr">133 </span>
<span id="L134" class="LineNr">134 </span><span class="muComment"># Scale (x, y) pixel coordinates to a complex plane where the viewport width</span>
<span id="L135" class="LineNr">135 </span><span class="muComment"># ranges from -2 to +2. Viewport height just follows the viewport's aspect</span>
<span id="L136" class="LineNr">136 </span><span class="muComment"># ratio.</span>
<span id="L137" class="LineNr">137 </span>
<span id="L138" class="LineNr">138 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='mandelbrot.mu.html#L138'>viewport-to-real</a></span> x: int, width: int, scene-cx: float, scene-width: float<span class="PreProc"> -> </span>_/<span class="Constant">xmm0</span>: float <span class="Delimiter">{</span>
<span id="L139" class="LineNr">139 </span> <span class="muComment"># 0 in the viewport goes to scene-cx - scene-width/2 </span>
<span id="L140" class="LineNr">140 </span> <span class="muComment"># width in the viewport goes to scene-cx + scene-width/2</span>
<span id="L141" class="LineNr">141 </span> <span class="muComment"># Therefore:</span>
<span id="L142" class="LineNr">142 </span> <span class="muComment"># x in the viewport goes to (scene-cx - scene-width/2) + x*scene-width/width</span>
<span id="L143" class="LineNr">143 </span> <span class="muComment"># At most two numbers being multiplied before a divide, so no risk of overflow.</span>
<span id="L144" class="LineNr">144 </span> <span class="PreProc">var</span> result/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> convert x
<span id="L145" class="LineNr">145 </span> result <span class="Special"><-</span> multiply scene-width
<span id="L146" class="LineNr">146 </span> <span class="PreProc">var</span> width-f/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> convert width
<span id="L147" class="LineNr">147 </span> result <span class="Special"><-</span> divide width-f
<span id="L148" class="LineNr">148 </span> result <span class="Special"><-</span> add scene-cx
<span id="L149" class="LineNr">149 </span> <span class="PreProc">var</span> two/eax: int <span class="Special"><-</span> copy <span class="Constant">2</span>
<span id="L150" class="LineNr">150 </span> <span class="PreProc">var</span> two-f/<span class="Constant">xmm2</span>: float <span class="Special"><-</span> convert two
<span id="L151" class="LineNr">151 </span> <span class="PreProc">var</span> half-scene-width/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> copy scene-width
<span id="L152" class="LineNr">152 </span> half-scene-width <span class="Special"><-</span> divide two-f
<span id="L153" class="LineNr">153 </span> result <span class="Special"><-</span> subtract half-scene-width
<span id="L154" class="LineNr">154 </span> <span class="PreProc">return</span> result
<span id="L155" class="LineNr">155 </span><span class="Delimiter">}</span>
<span id="L156" class="LineNr">156 </span>
<span id="L157" class="LineNr">157 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='mandelbrot.mu.html#L157'>viewport-to-imaginary</a></span> y: int, width: int, height: int, scene-cy: float, scene-width: float<span class="PreProc"> -> </span>_/<span class="Constant">xmm1</span>: float <span class="Delimiter">{</span>
<span id="L158" class="LineNr">158 </span> <span class="muComment"># 0 in the viewport goes to scene-cy - scene-width/2*height/width</span>
<span id="L159" class="LineNr">159 </span> <span class="muComment"># height in the viewport goes to scene-cy + scene-width/2*height/width</span>
<span id="L160" class="LineNr">160 </span> <span class="muComment"># Therefore:</span>
<span id="L161" class="LineNr">161 </span> <span class="muComment"># y in the viewport goes to (scene-cy - scene-width/2*height/width) + y*scene-width/width</span>
<span id="L162" class="LineNr">162 </span> <span class="muComment"># scene-cy - scene-width/width * (height/2 + y)</span>
<span id="L163" class="LineNr">163 </span> <span class="muComment"># At most two numbers being multiplied before a divide, so no risk of overflow.</span>
<span id="L164" class="LineNr">164 </span> <span class="PreProc">var</span> result/<span class="Constant">xmm0</span>: float <span class="Special"><-</span> convert y
<span id="L165" class="LineNr">165 </span> result <span class="Special"><-</span> multiply scene-width
<span id="L166" class="LineNr">166 </span> <span class="PreProc">var</span> width-f/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> convert width
<span id="L167" class="LineNr">167 </span> result <span class="Special"><-</span> divide width-f
<span id="L168" class="LineNr">168 </span> result <span class="Special"><-</span> add scene-cy
<span id="L169" class="LineNr">169 </span> <span class="PreProc">var</span> two/eax: int <span class="Special"><-</span> copy <span class="Constant">2</span>
<span id="L170" class="LineNr">170 </span> <span class="PreProc">var</span> two-f/<span class="Constant">xmm2</span>: float <span class="Special"><-</span> convert two
<span id="L171" class="LineNr">171 </span> <span class="PreProc">var</span> second-term/<span class="Constant">xmm1</span>: float <span class="Special"><-</span> copy scene-width
<span id="L172" class="LineNr">172 </span> second-term <span class="Special"><-</span> divide two-f
<span id="L173" class="LineNr">173 </span> <span class="PreProc">var</span> height-f/<span class="Constant">xmm2</span>: float <span class="Special"><-</span> convert height
<span id="L174" class="LineNr">174 </span> second-term <span class="Special"><-</span> multiply height-f
<span id="L175" class="LineNr">175 </span> <span class="PreProc">var</span> width-f/<span class="Constant">xmm2</span>: float <span class="Special"><-</span> convert width
<span id="L176" class="LineNr">176 </span> second-term <span class="Special"><-</span> divide width-f
<span id="L177" class="LineNr">177 </span> result <span class="Special"><-</span> subtract second-term
<span id="L178" class="LineNr">178 </span> <span class="PreProc">return</span> result
<span id="L179" class="LineNr">179 </span><span class="Delimiter">}</span>
</pre>
</body>
</html>
<!-- vim: set foldmethod=manual : -->
|