X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pages%2Fblog-0008.html-inc;h=706ea537074945bb91e1162b2494c72640b80ed3;hb=a05e5d4499fb58198e463162d0385e8a156e1f03;hp=63b22df87d29a10218a76761e96245907fa08420;hpb=d502f71f4cb7e6073e2629cdba69f20e7001b721;p=sdlgit%2FSDL-Site.git diff --git a/pages/blog-0008.html-inc b/pages/blog-0008.html-inc index 63b22df..706ea53 100644 --- a/pages/blog-0008.html-inc +++ b/pages/blog-0008.html-inc @@ -1,6 +1,77 @@

-Development Update +SDL RC 2.5 decides to play with PDL

-

A stoic stone will sit idle,
but will some effort,
A rolling rock will run!


In the past week the SDL Perl team has been busy! This is what we have accomplished


Commitment to Testing!

In an effort to focus on continuing our focus on testing we have setup a Smolder site for the SDL redesign process. Currently we have two platforms (linux, windows32) regularly tested on here. If there are more people following the redesign process and would like to share their test results; contact us at sdl-devel@perl.org and we will provide access to you.

SDL::Video

For the core development most of the focus has been on redesigning around the Video category of the SDL perl API. As of now we are 50% done. 19 functions out of 38 functions have been implemented and tested.


Site Redesign + Migration

On the end of the spectrum, Froggs has been hard at work on the graphical design of the site. More over with mst's help we will soon be migrating to http://sdl.perl.org.



Documentation

Moreover this week we have seen an increase effort from magnet on the SDL docs. Kudos!


SWIG Experimentation

Finally Katrina has begun looking into SWIG as alternative for SDL in the future.
\ No newline at end of file +PDL provides great number crunching capabilities to Perl and SDL provides game-developer quality real-time bitmapping and sound.
+You can use PDL and SDL together to create real-time,
+responsive animations and simulations.
+In this section we will go through the pleasures and pitfalls of working with both powerhouse libraries. -- David Mertnes
+
+
+

Creating a SDL Surface piddle


+PDL's core type is a piddle.
+Once a piddle is provided to PDL it can go do a numerous amounts of things.
+Please see the example in 'examples/cookbook/pdl.pl' in github.
+
+

Creating a simple piddle


+First lets get the right modules.
+
+
  use PDL;
+  use SDL::Rect;
+  use SDL::Video;
+  use SDL::Surface;
+  use SDL::PixelFormat;
+

+Suppose you want a surface of size (200,400) and 32 bit (RGBA).
+
+
my ( $bytes_per_pixel, $width, $height ) = ( 4, 200, 400 );
+

+Define the $width, $height and $bytes_per_pixel. Your $bytes_per_pixel is the number of bits (in this case 32) divided by 8 bits per byte. Therefore for our 32 bpp we have 4 Bpp;
+
+
my $piddle  = zeros( byte, $bytes_per_pixel, $width, $height );
+

+Create a normal $piddle with zeros, byte format and the Bpp x width x height dimensions.
+
+
my $pointer = $piddle->get_dataref();
+

+Here is where we get the acutal data the piddle is pointing to. We will have SDL create a new surface from this function.
+
+
my $surface = SDL::Surface->new_from( $pointer, $width, $height, 32,
+        $width * $bytes_per_pixel );
+

+Using the same dimensions we create the surface using SDL::Surface->new_form(). The $width * $Bpp is the scanline (pitch) of the surface in bytes.
+
+
warn "Made surface of $width, $height and ". $surface->format->BytesPerPixel;
+   return ( $piddle, $surface );
+

+Finally make sure that the surface acutally has the correct dimensions we gave.
+
+NOTE: $surface->format->BytesPerPixel must return 1,2,3,4. !!
+
+Now you can blit and use the surface as needed; and do PDL operations as required.
+
+

Operating on the Surface safely


+To make sure SDL is in sync with the data. You must call SDL::Video::lock before doing PDL operations on the piddle.
+
+
SDL::Video::lock_surface($surface);
+ 
+    $piddle ( :, 0 : rand(400), 0 : rand(200) ) .=   pdl( rand(225), rand(225), rand(255), 255 );
+

+After that you can unlock the surface to blit.
+
+
SDL::Video::unlock_surface($surface);
+

+

Errors due to BPP at blitting


+When blitting the new surface check for the return value to see if there has been a problem.
+
+
my $b = SDL::Video::blit_surface(
+        $surface,  SDL::Rect->new( 0, 0, $surface->w, $surface->h ),
+        $app, SDL::Rect->new(  ( $app->w - $surface->w ) / 2, ( $app->h - $surface->h ) / 2, $app->w, $app->h )
+       );
+ 
+    die "Could not blit: " . SDL::get_error() if ( $b == -1 );
+

+If the error message is 'Blit combination not supported' that means that the BPP is incorrect or incosistent with the dimensions. After that a simple update_rect will so your new surface on the screen.
+


+

\ No newline at end of file