diff options
Diffstat (limited to 'docs/aggpas/scanlines.agdoc.html')
| -rw-r--r-- | docs/aggpas/scanlines.agdoc.html | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/docs/aggpas/scanlines.agdoc.html b/docs/aggpas/scanlines.agdoc.html new file mode 100644 index 00000000..d85308fe --- /dev/null +++ b/docs/aggpas/scanlines.agdoc.html @@ -0,0 +1,195 @@ +<html><head><title>Anti-Grain Geometry - Scanlines and Scanline +Renderers</title> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<link rel="stylesheet" type="text/css" +href="scanlines.agdoc_files/agg.css"> +</head><body><a name="PAGE_SCANLINES"><b></b></a> + + +<table style="margin: 0px;" height="1px" width="640px" border="0" +cellpadding="0" cellspacing="0"> +<tbody><tr> +<td bgcolor="#583927"></td> +</tr> +</tbody></table> +<table style="margin: 0px;" width="640px" border="0" cellpadding="0" +cellspacing="0"> +<tbody><tr> +<td> +<table style="margin: 0px;" width="170px" border="0" cellpadding="0" +cellspacing="0"> +<tbody><tr><td><a href="http://www.antigrain.com/index.html" +class="mpmenu">Home/</a></td></tr> +<tr><td><a href="http://www.antigrain.com/doc/index.html" class="mpmenu">Table + of Content/</a></td></tr> +<tr><td><a href="" class="mpmenu"></a></td></tr> +<tr><td><a href="" class="mpmenu"></a></td></tr> +<tr><td><a href="" class="mpmenu"></a></td></tr> +<tr><td><a href="" class="mpmenu"></a></td></tr> +</tbody></table> +</td> +<td width="1px" bgcolor="#583927"></td> +<td style="text-align: right;" valign="top" width="450px"> +<table style="margin: 0px;" border="0" cellpadding="0" cellspacing="0"> +<tbody><tr> +<td><img src="scanlines.agdoc_files/agg_logo.gif" border="0"></td> +</tr> +<tr> +<td> +<table style="margin: 0px;" border="0" cellpadding="0" cellspacing="0"> +<tbody><tr height="15px"> +<td> <a class="topmenu" +href="http://www.antigrain.com/news/index.html">News</a> </td> +<td width="1px" bgcolor="#8e521d"></td> +<td> <a class="topmenu" +href="http://www.antigrain.com/doc/index.html">Docs</a> </td> +<td width="1px" bgcolor="#8e521d"></td> +<td> <a class="topmenu" +href="http://www.antigrain.com/download/index.html">Download</a> </td> +<td width="1px" bgcolor="#8e521d"></td> +<td> <a class="topmenu" +href="http://www.antigrain.com/maillist/index.html">Mailing List</a> </td> +<td width="1px" bgcolor="#8e521d"></td> +<td> <a class="topmenu" +href="http://www.antigrain.com/cvs/index.html">CVS</a> </td> +</tr> +</tbody></table> +</td> +</tr> +</tbody></table> +</td> +</tr> +</tbody></table> +<table style="margin: 0px;" height="1px" width="640px" bgcolor="#583927" + border="0" cellpadding="0" cellspacing="0"><tbody><tr><td></td></tr></tbody></table> + + +<table width="640px"><tbody><tr><td style="text-align: justify;"><p> +</p></td></tr></tbody></table> + +<table width="640px"><tbody><tr><td><h1>Scanlines and Scanline Renderers</h1></td></tr></tbody></table> + +<table class="toc" width="640px"><tbody><tr><td> + <div style="margin-left: 2em; padding: 3px; font-size: 14px;"><a +href="#toc0001"><b>Scanline Containers</b></a> + <div style="margin-left: 2em; font-size: 12px;"><a +href="#toc0002">Introduction</a></div> + <div style="margin-left: 2em; font-size: 12px;"><a +href="#toc0003">Interfaces</a> + <div style="margin-left: 2em; font-size: 12px;"><a +href="#toc0004">Filling Interface (put)</a></div> + <div style="margin-left: 2em; font-size: 12px;"><a +href="#toc0005">Iterating Interface (get)</a></div></div></div> + <div style="margin-left: 2em; padding: 3px; font-size: 14px;"><a +href="#toc0006"><b>Scanline Renderers</b></a></div> + +</td></tr></tbody></table> + + +<h2>Scanline Containers<a name="toc0001"></a></h2> + +<h3>Introduction<a name="toc0002"></a></h3> + +<table width="640px"><tbody><tr><td style="text-align: justify;"><p>The +low level renderers operate with +simplest data and they are very simple too. In fact, the pixel format +renderers are not the obligatory part of the library and can be +replaced or rewritten. For example, if you have an API with similar +functionality, but hardware accelerated, it will be better to use it +instead of pure software blending (the low level renderers are +essentially alpha-blenders). It's also possible to use Intel SSE/SSE2 +to write optimized renderers. All other rendering functionality in +AGG is based on these simple classes.</p></td></tr></tbody></table> + +<table width="640px"><tbody><tr><td style="text-align: justify;"><p>To +draw Anti-Aliased primitives one shoud <b>rasterize</b> them first. +The primary rasterization technique in AGG is scanline based. That is, +a polygon is converted into a number of horizontal scanlines and then +the scanlines are being rendered one by one. Again, the scanline +rasterizer is not the only class that can produce scanlines. It can +be some container or even your own super-ultra-mega rasterizer.</p></td></tr></tbody></table> + +<table width="640px"><tbody><tr><td style="text-align: justify;"><p>To +transfer information from a rasterizer to the scanline renderer +there scanline containers are used. +A scanline consists of a number of horizontal, non-intersecting spans. +All spans must be ordered by X. It means that there is no sorting +operation provided, the order must be perserved when adding spans +to the scanline. If the order is not guaranteed it can result in +undefined behaviour.</p></td></tr></tbody></table> + +<table width="640px"><tbody><tr><td style="text-align: justify;"><p>In <b>AGG</b> + there are three types of scanline containers: +</p><ul type="disc"> +<li><code>scanline_u</code> - unpacked scaline container</li> +<li><code>scanline_p</code> - packed scanline container</li> +<li><code><a +href="http://www.antigrain.com/__code/include/agg_scanline_bin.h.html#scanline_bin">scanline_bin</a></code> + - container for binary, “aliased” scanlines</li></ul><p></p></td></tr></tbody></table> + +<table width="640px"><tbody><tr><td style="text-align: justify;"><p>First + two containers can keep <b><nobr>Anti-Aliasing</nobr></b> information, +the third one cannot.</p></td></tr></tbody></table> + +<table class="warning" width="640px"><tbody><tr><td><b>IMPORTANT!</b><br> +All the scanline containers are optimized for speed, not for +memory usage. In fact, it allocates memory for the worst case, +so there is some overhead. It's not critical when you use only +few scanline containers, but it's not a good idea to use an +array of scanlines to store the whole shape because it will take +more memory than the resulting image. +</td></tr></tbody></table> + + +<table width="640px"><tbody><tr><td style="text-align: justify;"><p>The +difference between <b>packed</b> and <b>unpacked</b> scanline +containers is that the <b>unpacked</b> scaline always keeps the +coverage values for all pixels including the ones that are +fully covered by a polygon. In the <b>packed</b> scanline +all pixels with the same coverage value are merged into <b>solid</b> +spans. +</p></td></tr></tbody></table><table width="640px"><tbody><tr><td><center><img + src="scanlines.agdoc_files/scanline_u.gif" title="" border="0"><br><i></i></center></td></tr></tbody></table> +<table width="640px"><tbody><tr><td><center><img +src="scanlines.agdoc_files/scanline_p.gif" title="" border="0"><br><i></i></center></td></tr></tbody></table> + +<table width="640px"><tbody><tr><td style="text-align: justify;"><p>It +can seem it's always better to use the packed version, but in +practice it's not so. The scanline_p works faster when rendering +large solid polygons, that is when the area of the polygon is +much larger than the perimeter in the meaning of the number +of pixels. But when renering text it's definitely better to use +the scanline_u because of much less number of processed spans +The difference is about three times and the number of spans +is also important for the overall performance. Besides, in most +of the span generators, such as gradients, Gouraud shader, or +image transformers, the number of spans becomes even more critical, +and so, the scanline_p is not used there.</p></td></tr></tbody></table> + + +<h3>Interfaces<a name="toc0003"></a></h3> + +<h4>Filling Interface (put)<a name="toc0004"></a></h4> + +<h4>Iterating Interface (get)<a name="toc0005"></a></h4> + + +<br><h2>Scanline Renderers<a name="toc0006"></a></h2> + +<br><table style="margin: 0px;" height="1px" width="640px" +bgcolor="#583927" border="0" cellpadding="0" cellspacing="0"><tbody><tr><td></td></tr></tbody></table> +<table width="640px" border="0" cellpadding="0" cellspacing="0"> +<tbody><tr><td><center><span class="authors"> +Copyright <span class="larger">©</span> 2002-2006 +<a href="http://www.antigrain.com/mcseem/index.html"><b>Maxim Shemanarev</b></a> +</span></center></td></tr> +<tr><td><center><span class="authors"> +Web Design and Programming +<a href="http://www.antigrain.com/mcseem/index.html"><b>Maxim Shemanarev</b></a> +</span></center></td></tr> +</tbody></table> +<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br> +<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br> +<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br> +<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br> +</body></html>
\ No newline at end of file |