Graphics::GVG - Game Vector Graphics
my $SCRIPT = <<'END'; %color = #FF33FFFF; line( %color, 0.0, 0.0, 1.0, 1.1 ); glow { circle( %color, 0, 0, 0.9 ); rect( %color, 0, 1, 0.7, 0.4 ); } END my $gvg = Graphics::GVG->new; my $ast = $gvg->parse( $SCRIPT );
Parses scripts that describe vectors used for gaming graphics. The script is parsed into an Abstract Syntax Tree (AST), which can then be transformed into different forms. For example, Graphics::GVG::OpenGLRender generates Perl code that can be compiled and called inside a larger Perl/OpenGL program.
Compared to SVG, GVG scripts are very simple. They look like a series of C function calls, with blocks that generate various effects. Each statement is ended by a semicolon.
The coordinate space follows general OpenGL conventions, where x/y coords are floating point numbers between -1.0 and 1.0, using the right-hand rule.
Comments start with '//' and go to the end of the line
There aren't any.
There aren't any. I said this was a simple language, remember?
GVG functions can take several data types:
Integer -- a series of digits with no decimal point, like 1234.
1234
Float -- a series of digits, which can contain a decimal point, like 1.234. While you can specify as many digits as you want, note that these are ultimately limited to double-precision IEEE floats.
1.234
Color -- starts with a '#', and then is followed by 8 hexidecimal digits, in RGBA form, like #5cd2bbff. Hex digits can be upper or lower case.
#5cd2bbff
Integers and floats can both use '-' to indicate a negative number.
The type system is both static and strong; you can't assign an integer to a color parameter.
Data types can be saved in variables, which each data type getting its own sigal.
&x = 2; // Integer $y = 1.23; // Float %color = #ff33aaff; // Color poly( %color, 0, $y, 4.3, &x, 30.2 );
Variables can be redefined at any time:
%color = #ff33aaff; line( %color, 0, 1, 1, 0 ); %color = #aabbaaff; line( %color, 1, 0, 1, 1 );
Meta info is general things that renderers may need to work with, and are usually dependent on a larger context. For instance, you might put in a !size = "small";, which might be sized relative to tiny, medium, large, huge, etc. objects in the rest of the system.
!size = "small";
Meta statements start with ! and are followed by a name and a value. The value can be a float, integer, or a string (surrounded by double quotes).
!
!name = "flying thing"; !size = "small"; !side = 1;
There are several drawing functions for defining vectors.
line( %color, $x1, $y1, $x2, $y2 );
A line of the given %color, going from coordinates $x1,$y1 to $x2,$y2.
%color
$x1,$y1
$x2,$y2
circle( %color, $cx, $cy, $r );
A circle of the given %color, centered at $cx,$cy, with radius $r.
$cx,$cy
$r
rect( %color, $x, $y, $width, $height );
A rectangle of the given %color, starting at $x,$y, and then going to $x + $width and $y + $height.
$x,$y
$x + $width
$y + $height
ellipse( %color, $cx, $cy, $rx, $ry );
An ellipse of the given %color, centered at $cx,$cy, with respective radii $rx and $ry.
$rx
$ry
point( %color, $x, $y, $size );
A point of the given %color, at $x,$y, with size $size.
$size
poly( %color, $cx, $cy, $r, &sides, $rotate );
A regular polygon of the given %color, centered at $cx,$cy, rotated $rotate degrees, with radius $r, and &sides number of sides.
$rotate
&sides
Effects can be applied to drawing functions by enclosing them in a block (inside {...} characters) named for a certain effect.
{...}
For example, a glow effect can be set on lines with:
glow { circle( %color, 0, 0, 0.9 ); rect( %color, 0, 1, 0.7, 0.4 ); }
How this is rendered is dependent on the renderer. An OpenGL renderer may show an actual neon glow effect, while a renderer for a physics library may ignore it entirely.
The parse results in an Abstract Syntax Tree, which is represented with Perl objects. Developers writing renderers will need to take the AST and walk it to generate their desired output. See Graphics::GVG::AST for a description of the tree objects.
Takes a GVG script as input. On success, returns an abstract syntax tree. Otherwise, throws a fatal error.
Copyright (c) 2016 Timm Murray All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
To install Graphics::GVG, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Graphics::GVG
CPAN shell
perl -MCPAN -e shell install Graphics::GVG
For more information on module installation, please visit the detailed CPAN module installation guide.