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<html><head><title>Anti-Grain Geometry - Introduction</title>
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</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td><h1>Introduction<span
class="subtitle"><br>Overview and Basic Concepts</span></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>Brief Overview</b></a>
<div style="margin-left: 2em; font-size: 12px;"><a
href="#toc0002">Yet Another Invention of the Wheel</a></div>
<div style="margin-left: 2em; font-size: 12px;"><a
href="#toc0003">Gentle Criticism</a></div>
<div style="margin-left: 2em; font-size: 12px;"><a
href="#toc0004">The Proposal</a></div>
<div style="margin-left: 2em; font-size: 12px;"><a
href="#toc0005">Anti-Aliasing and Subpixel Accuracy</a></div></div>
<div style="margin-left: 2em; padding: 3px; font-size: 14px;"><a
href="#toc0006"><b>Basic Concepts</b></a>
<div style="margin-left: 2em; font-size: 12px;"><a
href="#toc0007">Design of the Library</a></div>
<div style="margin-left: 2em; font-size: 12px;"><a
href="#toc0008">Colors, Color Spaces, and Pixel Formats</a></div>
<div style="margin-left: 2em; font-size: 12px;"><a
href="#toc0009">Coordinate Units</a></div>
<div style="margin-left: 2em; font-size: 12px;"><a
href="#toc0010">AGG Building and Coding Notes</a></div></div>
<div style="margin-left: 2em; padding: 3px; font-size: 14px;"><a
href="#toc0011"><b>About this Manual</b></a></div>
</td></tr></tbody></table>
<h2>Brief Overview<a name="toc0001"></a></h2>
<h3>Yet Another Invention of the Wheel<a name="toc0002"></a></h3>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p><b><nobr>Anti-Grain</nobr>
Geometry</b> (<b>AGG</b>) is a general purpose graphical toolkit
written completely in
standard and platform independent <b>C++</b>.
It can be used in many areas of computer programming where high quality
2D
graphics is an essential part of the project. For example, if you render
2D geographic maps <b>AGG</b> is a must. <b>AGG</b> uses only <b>C++</b>
and standard
C runtime functions, such as <b>memcpy, sin, cos, sqrt</b>, etc.
The basic algorithms don't even use <b>C++ Standard Template Library</b>.
Thus, <b>AGG</b> can be used in a very large
number of applications, including embedded systems.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>On
the other hand, <b>AGG</b> allows you to replace any part of the
library, if, for example,
it doesn't fit performance requirements. Or you can add another color
space if needed.
All of it is possible because of extensive using of <b>C++</b> <b>template</b>
mechanism.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p><b><nobr>Anti-Grain</nobr>
Geometry</b> is not a solid graphic library and it's not very easy to
use.
I consider <b>AGG</b> as a <b>“tool to create other tools”</b>. It means
that there's
no <b>“Graphics”</b> object or something like that, instead, <b>AGG</b>
consists of
a number of loosely coupled algorithms that can be used together or
separately.
All of them have well defined interfaces and absolute minimum of
implicit or explicit
dependencies.</p></td></tr></tbody></table>
<h3>Gentle Criticism<a name="toc0003"></a></h3>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Most
of the graphic libraries have a single class like <b>“Graphics”</b>
in GDI+, that has hundred or even thousands of functions. This object
can exist implicitly, like in OpenGL. Anyway, all commonly used
graphical tool kits, including Java2D, DisplayPDF, SVG, and other very
good ones have this kind of a class explicitly or implicitly.
That's simple and in some cases quite suitable, but always very
restrictive. It works well only in simple cases, at least I haven't
seen a graphical library that would completely fit all my needs.
Moreover, all that kinds of libraries or standards have a
syndrome of giantism. Most of the functionality is never
used, but some simple things are impossible to achieve. Herein, the
graphical engines (or libraries) typically weigh tons of
mega-bytes. If you take the most advanced SVG viewer,
<a href="http://www.adobe.com/svg/main.html"><img
src="introduction.agdoc_files/link.gif" border="0">Adobe SVG</a>, it
works well only with
simplest primitives. As soon as you try to use some advanced things,
like interactive SVG with different graphical filters, you will have
memory leaks, or even crashes. It's not because it has bad design,
it's because the proposed possibilities assume extremely complex design.
The design itself becomes an <b>NP-complete</b> task, which is
impossible
to perceive by a human mind as impossible to perceive the infinity.</p></td></tr></tbody></table>
<h3>The Proposal<a name="toc0004"></a></h3>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>The
primary goal of <b><nobr>Anti-Grain</nobr> Geometry</b> is to break this
ancient as mammoth's manure
tradition and show you the beauty of stability, lightness,
flexibility, and freedom. The basic concepts can seem not very
conventional at the beginning, but they are very close to the ones
used in <b>STL</b>. But there's a big difference too. <b>STL</b> is a
general <b>C++</b> tool
while <b>AGG</b> is <b>C++</b> graphics. You usually use <b>STL</b> in
your applications directly
as a convenient toolkit. I wouldn't say it's a good idea to use <b>AGG</b>
in the
very same way. A good idea is to create a
lightweight, problem oriented wrapper over <b>AGG</b> to solve your
particular
tasks. How can that be different from that very GDI+ then? The first
thing is that you have total control upon that wrapper. <b><nobr>Anti-Grain</nobr>
Geometry</b> just provides
you a set of basic algorithms and flexible design with the minimum of
implicit
or explitit dependencies. You and only you define the interface,
conversion pipelines, and the form of output. You can even simulate a
part
of any existing graphical interface. For example, you can use <b>AGG</b>
rasterizer
to display graphics on the screen and direct Windows GDI calls for
printing,
incorporating it into a single API. Not convincing? Look at the quality
of
rendering in <b>GDI+</b> and <b>AGG</b>:
</p></td></tr></tbody></table><a name="GDIP_AGG_QUALITY"><b></b></a><table
width="640px"><tbody><tr><td><center><img
src="introduction.agdoc_files/qual_gdip_agg.gif" title="Quality of
Rendering" border="0"><br><i>Quality of Rendering</i></center></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>But
most of all, your applications become absolutely portable, if
your design is smart enough. <b>AGG</b> can be also a tool to combine
different
outputs in a uniform API. Particularly, you can use <b>AGG</b> to
generate
raster images on the server side in your Web-Based applications. And it
all
can be <b>cross-platform!</b></p></td></tr></tbody></table>
<a name="PAGE_ANTI_ALIASING"><b></b></a>
<h3>Anti-Aliasing and Subpixel Accuracy<a name="toc0005"></a></h3>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p><b><nobr>Anti-Aliasing</nobr></b>
is a very well known technique used to improve the visual quality of
images when displaying them on low resolution devices. It's based on the
properties
of the human vision. Look at the following picture and try to guess what
it means.
</p></td></tr></tbody></table><table width="640px"><tbody><tr><td><center><img
src="introduction.agdoc_files/stereo_enlarged.gif" title="" border="0"><br><i></i></center></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Well,
it's a word drawn with <b><nobr>Anti-Aliasing</nobr></b>. In terms of
Kotelnikov-Shannon's theorem,
the maximal frequency of the image is far above of the Shannon limit.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p><img
src="introduction.agdoc_files/stereo_small.gif" title=""
style="border-color: rgb(255, 255, 255);" align="left" border="4"><!---->
Now look at the same picture that has normal size and <b>within the
context</b>. You easily
recognize word <b>“stereo”</b>. However, the pictrures are exactly the
same. The first
one is just an enlarged version of the last one. This very property
allows us to
reconstruct missing information on the basis of accumulated experience. <b><nobr>Anti-Aliasing</nobr></b>
doesn't make you see better, it basically makes you brain work better
and reconstruct
missing details. The result is great. It allows us to draw much more
detailed maps for
example.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>But
the point is not only in <b><nobr>Anti-Aliasing</nobr></b> itself. The
point is we can draw primitives
with <b>Subpixel Accuracy</b>. It's especially important for the visual
thickness of the lines.
First, let us see that even with simple Bresenham line interpolator we
can achieve
a better result if we use <b>Subpixel Accuracy</b>. The following
picture shows enlarged
results of the simple Bresenham interpolator.
</p></td></tr></tbody></table><a name="SUBPIXEL_BRESENHAM"><b></b></a><table
width="640px"><tbody><tr><td><center><img
src="introduction.agdoc_files/subpixel_bresenham.gif" title="A Bresenham
Line Rendered with Subpixel Accuracy" border="0"><br><i>A Bresenham
Line Rendered with Subpixel Accuracy</i></center></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Consider
cases (2) and (3). The thin black lines are what we need to
interpolate.
If we use <b>Subpixel Accuracy</b> we will really have two different
sets of pixels
displayed, despite of the fact that the begins and ends of both lines
fall into
the same pixels. And the lines have really different tangents, which is
very important.
If we use a classical Bresenham, without considering the <b>Subpixel
Accuracy</b> we will see
result (1) in all cases. That's especially important to approximate
curves with short
line segments. But if we use <b><nobr>Anti-Aliasing</nobr></b> plus <b>Subpixel
Accuracy</b> we can do much better.
Look at that difference.
</p></td></tr></tbody></table><table width="640px"><tbody><tr><td
style="text-align: center;"><p>
<img src="introduction.agdoc_files/aliased_pix_accuracy.gif" title=""
border="0"><!---->
<img src="introduction.agdoc_files/aliased_subpix_accuracy.gif" title=""
border="0"><!---->
<img src="introduction.agdoc_files/anti_aliased.gif" title="" border="0"><!---->
</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Here
all three spirals are approximated with short straight line segments.
The left one is drawn using regular integer Bresenham, when the
coordinates
are rounded off to pixels (you will have a similar result if you use
Winwows GDI MoveTo/LineTo, for example). The one in the middle uses a
modified
integer Bresenham with precision of 1/256 of a pixel. And the right one
uses
the same 1/256 accuracy, but with <b><nobr>Anti-Aliasing</nobr></b>.
Note that it's very important
to have a possibility of real subpixel positioning of the line segments.
If we use regular pixel coordinates with <b><nobr>Anti-Aliasing</nobr></b>,
the spiral will look
smooth but still, as ugly as the one on the left.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>The <b>Subpixel
Accuracy</b> is even more important to control the visual thickness
of the lines. It's possible only if we have good algorithms of
<b><nobr>Anti-Aliasing</nobr></b>. On the other hand, there's no much
sense of <b><nobr>Anti-Aliasing</nobr></b>
if can set the line width with the discretness of one pixel only. <b><nobr>Anti-Aliasing</nobr></b>
and <b>Subpixel Accuracy</b> always work in cooperation.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Modern
displays have resolutions of at most 120 DPI, while <b>Subpixel
Accuracy</b>
is actual up to 300 DPI. The following picture shows lines with
thickness
starting from 0.3 pixels and increasing by 0.3 pixel.
</p></td></tr></tbody></table><a name="LINE_THICKNESS"><b></b></a><table
width="640px"><tbody><tr><td><center><img
src="introduction.agdoc_files/line_thickness.gif" title="Lines Rendered
with Anti-Aliasing and Subpixel Accuracy" border="0"><br><i>Lines
Rendered with Anti-Aliasing and Subpixel Accuracy</i></center></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>There
are two more examples of rendering with <b>Subpixel Accuracy</b>.</p></td></tr></tbody></table>
<a name="SUBPIXEL_ACCURACY1"><b></b></a><table width="640px"><tbody><tr><td><center><img
src="introduction.agdoc_files/subpixel_accuracy1.gif" title="Circles
Rendered with Anti-Aliasing and Subpixel Accuracy" border="0"><br><i>Circles
Rendered with Anti-Aliasing and Subpixel Accuracy</i></center></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>
<a name="SUBPIXEL_ACCURACY2"><b></b></a><table width="640px"><tbody><tr><td><center><img
src="introduction.agdoc_files/subpixel_accuracy2.gif" title="Cute
Lions" border="0"><br><i>Cute Lions</i></center></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Note
that the appearance of the small ones remains consistent
despite of lost details.
</p></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>
<br><h2>Basic Concepts<a name="toc0006"></a></h2>
<h3>Design of the Library<a name="toc0007"></a></h3>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p><b><nobr>Anti-Grain</nobr>
Geometry</b> is designed as a set of loosely coupled algorithms and
class templates
united with a common idea, so that all the components can be easily
combined.
Also, the template based design allows you to replace any part of the
library without the
necessity to modify a single byte in the existing code.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Also
<b>AGG</b> is designed keeping in mind extensibility and flexibility.
Basically I just wanted
to create a toolkit that would allow me (and anyone else) to add new
fancy
algorithms very easily.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p><b>AGG</b>
does not dictate you any style of its use, you are free to use any part
of it. However, <b>AGG</b> is often associated with a tool for rendering
images in memory.
That is not quite true, but it can be a good starting point in studying.
The tutorials describe the use of <b>AGG</b> starting from the low level
functionality that
deals with frame buffers and pixels.
Then you will gradually understand how to abstract different parts
of the library and how to use them separately. Remember, the raster
picture
is often not the only thing you want to obtain, you will probably want
to
print your graphics with highest possible quality and in this case you
can
easily combine the “vectorial” part of the library with some API like
Windows GDI,
having a common external interface.
If that API can render multi-polygons with non-zero and even-odd filling
rules
it's all you need to incorporate <b>AGG</b> into your application. For
example, Windows
API PolyPolygon perfectly fits these needs, except certain advanced
things like
gradient filling, Gouraud shading, image transformations, and so on. Or,
as
an alternative, you can use all <b>AGG</b> algorithms producing high
resolution pixel
images and then to send the result to the printer as a pixel map.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Below
is a typical brief scheme of the <b>AGG</b> rendering pipeline. <br>
<a name="TYPICAL_SCHEME"><b></b></a><table align="left"><tbody><tr><td><center><img
src="introduction.agdoc_files/typical_scheme.gif" title="Typical Scheme
of the Rendering Pipeline" border="0"></center></td></tr><tr><td><i><center>Typical
Scheme of the Rendering Pipeline</center></i></td></tr></tbody></table>
<br>
Please note that any component between the “Vertex Source” and
“Screen Output” is not mandatory. It all depends on your particular
needs. For example,
you can use your own rasterizer, based on Windows API. In this case you
won't need
the AGG rasterizer and renderers. Or, if you need to draw only lines,
you can use the
AGG <b>outline</b> rasterizer that has certain restrictions but works
faster. The number of
possibilities is endless.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Here:
</p><ul type="disc">
<li><b>Vertex Source</b> is some object that produces polygons or
polylines as
a set of consecutive 2D vertices with commands like “MoveTo”,
“LineTo”.
It can be a container or some other object that generates vertices on
demand.</li>
<li><b>Coordinate conversion pipeline</b> consists of a number of
coordinate converters.
It always works with vectorial data (X,Y) represented as floating
point numbers
<nobr>(double)</nobr>. For example, it can contain an affine
transformer, outline (stroke)
generator, some marker generator (like arrowheads/arrowtails), dashed
lines
generator, and so on. The pipeline can have branches and you also can
have any
number of different pipelines. You also can write your own converter
and include
it into the pipeline.</li>
<li><b>Scanline Rasterizer</b> converts vectorial data into a number of
horizontal scanlines.
The scanlines usually (but not obligatory) carry information about <b><nobr>Anti-Aliasing</nobr></b>
as
“coverage” values. </li>
<li><b>Renderers</b> render scanlines, sorry for the tautology. The
simplest example is
solid filling. The renderer just adds a color to the scanline and
writes the result
into the rendering buffer. More complex renderers can produce
multi-color result,
like gradients, Gouraud shading, image transformations, patterns, and
so on.</li>
<li><b>Rendering Buffer</b> is a buffer in memory that will be displayed
afterwards. Usually
but not obligatory it contains pixels in format that fits your video
system. For example,
24 bits <nobr>B-G-R</nobr>, 32 bits <nobr>B-G-R-A</nobr>, or 15 bits <nobr>R-G-B-555</nobr>
for Windows.
But in general, there're no restrictions on pixel formats or color
space if
you write your own low level class that supports that format.</li></ul><p></p></td></tr></tbody></table>
<h3>Colors, Color Spaces, and Pixel Formats<a name="toc0008"></a></h3>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Colors
in <b>AGG</b> appear only in renderers, that is, when you actually put
some data
to the rendering buffer. In general, there's no general purpose
structure or
class like <b>“color”</b>, instead, <b>AGG</b> always operates with
concrete color space.
There are plenty of color spaces in the world, like RGB, HSV, CMYK,
etc., and
all of them have certain restrictions. For example, the RGB color space
is just a
poor subset of colors that a human eye can recognize. If you look at the
full <a href="http://www.efg2.com/Lab/Graphics/Colors/Chromaticity.htm"><img
src="introduction.agdoc_files/link.gif" border="0"><b>CIE Chromaticity
Diagram</b></a>, you will see that
the RGB triangle is just a little part of it.
</p></td></tr></tbody></table><a name="CIE_1931"><b></b></a><table
width="640px"><tbody><tr><td><center><img
src="introduction.agdoc_files/cie_1931.jpg" title="CIE Chromaticity
Diagram and the RGB Gamut" border="0"><br><i>CIE Chromaticity Diagram
and the RGB Gamut</i></center></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>In
other words there are plenty
of colors in the real world that cannot be reproduced with RGB, CMYK,
HSV, etc.
Any color space except the one existing in Nature is restrictive.
Thus, it was decided not to introduce such an object like <b>“color”</b>
in order
not to restrict the possibilities in advance. Instead, there are objects
that
operate with concrete color spaces. Currently there are agg::<a
href="http://www.antigrain.com/__code/include/agg_color_rgba.h.html#rgba">rgba</a>
and agg::<a
href="http://www.antigrain.com/__code/include/agg_color_rgba.h.html#rgba8">rgba8</a>
that operate with the most popular <b>RGB</b> color space (strictly
speaking there's
RGB plus Alpha). The RGB color space is used with different pixel
formats, like
<nobr>24-bit</nobr> RGB or <nobr>32-bit</nobr> RGBA with different order
of color components.
But the common property of all of them is that they are essentially RGB.
Although, <b>AGG</b> doesn't explicitly support any other color spaces,
there is at
least a potential possibility of adding them. It means that all class
and
function templates that depend on the <b>“color”</b> type are
parameterized with the
<b>“ColorT”</b> argument.</p></td></tr></tbody></table>
<h3>Coordinate Units<a name="toc0009"></a></h3>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Basically,
<b>AGG</b> operates with coordinates of the output device.
On your screen there are pixels. But unlike many other libraries and
APIs
<b>AGG</b> initially supports <b>Subpixel Accuracy</b>. It means that
the coordinates are represented as
<b>doubles</b>, where fractional values actually take effect.
<b>AGG</b> doesn't have an embedded conversion mechanism from <u>world</u>
to <u>screen</u>
coordinates in order not to restrict your freedom. It's very important
where and when
you do that conversion, so, different applications can require different
approaches.
<b>AGG</b> just provides you a transformer of that kind, namely,
that can convert your own <u>view port</u> to the <u>device</u> one. And
it's your responsibility
to include it into the proper place of the pipeline. You can also write
your own
very simple class that will allow you to operate with millimeters,
inches, or any
other physical units.</p></td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>Internally,
the rasterizers use integer coordinates of the format
24.8 bits, that is, 24 bits for the integer part and 8 bits for the
fractional one. In other words, all the internal coordinates are
multiplied
by 256. If you intend to use <b>AGG</b> in some embedded system that has
inefficient
floating point processing, you still can use the rasterizers with their
integer
interfaces. Although, you won't be able to use the floating point
coordinate pipelines
in this case.</p></td></tr></tbody></table>
<h3>AGG Building and Coding Notes<a name="toc0010"></a></h3>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p><b><nobr>Anti-Grain</nobr>
Geometry</b> doesn't have any rich and automated environvents to build.
<b>AGG</b> mantra is
<b>“It just compiles and works”</b>. It doesn't have any installation
packages either. Maybe it's not very good from the point of view of
automated
configuring and making of applications (like it's commonly used on
Unix),
but all you need to do is just add <b>AGG</b> source files into your
distribution
package as if they were your files.
As a benefit of this approach, you won't have any problems
with configuration files and endless <b>#ifdef…#elif…#endif</b>. This is
possible because <b>AGG</b> has absolute minimum of external
dependencies. For Unix
there are the simplest possible <b>Makefiles</b> to build the <b>.a</b>
library, for
Windows there's no library created at all. All the demo examples just
include
the necessary source files. This practice allows for more convenient
debugging
process; in fact, almost all the examples are actually used to implement
and debug the algorithms. It also advantages stability of the library,
because all
the algorithms suffer very deep testing in the conditions near to
operational.
</p></td></tr></tbody></table><table class="note" width="640px"><tbody><tr><td><b>NOTE</b><br>
If you want to use <b>AGG</b> in Windows Visual C++ environment, please
note that
there's no <b>“stdafx.h”</b> file used. It's <a
href="http://www.microsoft.com/"><img
src="introduction.agdoc_files/link.gif" border="0"><b>Microsoft</b></a>
specific and not
a part of C/C++ standard libraries, but <a
href="http://www.microsoft.com/"><img
src="introduction.agdoc_files/link.gif" border="0"><b>Microsoft</b></a>
just enforces to use it.
To successfully use <b>AGG</b> in Visual C++ projects don't forget to
turn off the
<b>“Precompiled Headers”</b> option for all <b>AGG</b> source files.
Besides, if you
link <b>AGG</b> with static <b>MFC</b> you will probably have
duplicating <code>new</code> and <code>delete</code>
operators when linking. It's not because of <b>AGG</b>, it's because of <b>MFC</b>.
You will have the very same problem when you try to use any other <b>C++</b>
code that calls <code>new/delete</code> and doesn't include <b><nobr>stdafx.h</nobr></b>.
To resolve this situation follow the
<a
href="http://support.microsoft.com/default.aspx?scid=kb;en-us;q148652"><img
src="introduction.agdoc_files/link.gif" border="0"><b>Microsoft
recommendations</b></a> or just search in <a
href="http://www.google.com/"><img
src="introduction.agdoc_files/link.gif" border="0"><b>Google</b></a> for
<b>“<nobr>148652 LNK2005</nobr>”</b>.
</td></tr></tbody></table>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>As
it was mentioned above, <b>AGG</b> uses <b>C++</b> template mechanism
very actively.
However, it uses only well known and proven language constructions. A
good compatibility
is one of the primary aspirations. <b>C++</b> gurus can be suprised that
<b>AGG</b> doesn't use <b>STL</b>,
for example. It's done intentionally, in order not to have extra
dependencies
where the necessity of <b>STL</b> containers is very little. Of course,
it doesn't
prevent you from using <b>STL</b> or any other popular tools in a higher
level.
<b>AGG</b> is designed to have absolute minumum of potential conflicts
with existing <b>C++</b>
libraties, tools and technologies.</p></td></tr></tbody></table>
<br><h2>About this Manual<a name="toc0011"></a></h2>
<table width="640px"><tbody><tr><td style="text-align: justify;"><p>As
it was said before <b>AGG</b> provides many different levels of
functionality, so
that you can use it in many different ways. For example, you may want to
use
<b>AGG</b> rasterizers without the scanline renderers. But for the sake
of
consistency and graduality we will start from the very beginning and
describe
all the functionality with examples. This approach might be slower than
some
“Quick Start”, but it will allow you to understand the conceps of the
design.
It is really useful because you will know how to replace certain classes
and
algorithms with your own, or how to extend the library. Particularly,
the
scanline renderers are platform independent, but not the fastest. You
may want
to write your own, optimized ones, but oriented to some hardware
archtecture, like SSE2.</p></td></tr></tbody></table>
<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>
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