X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pages%2Fblog-0011.html-inc;h=706ea537074945bb91e1162b2494c72640b80ed3;hb=1d5d4d44a3acf89f7820195b5016f4ebc4489250;hp=8d5d72914e3327bf0ddbd588685560a9434552ff;hpb=769d193e7a4b5eeebd1f248a084ae4f2495df071;p=sdlgit%2FSDL-Site.git diff --git a/pages/blog-0011.html-inc b/pages/blog-0011.html-inc index 8d5d729..706ea53 100644 --- a/pages/blog-0011.html-inc +++ b/pages/blog-0011.html-inc @@ -1,6 +1,77 @@

-Thanks nothingmuch, and updates +SDL RC 2.5 decides to play with PDL

-
struggle,
live,
cease,
die

After a struggling with XS and opaque C structs in the experimental SDL::Rect for a long time. Nothingmuch comes along and solves my problem with this beautiful module XS::Object::Magic. So I will start moving my ugly XS to Magic Land.

SDL Perl Tutorials

This past week I have been working on the sorry state of SDL Perl tutorials. Currently I am working on a Tetris Clone. I am hoping to have it done by next Thrusday for TPM meeting. This tutorial is a mix of several tutorials I found online. Another Lunar Lander tutorial has been submitted by Nelson Ferraz.

If anyone has any really good tutorials for game development (regardless of language) or even request of tutorials. Send it my way I will look into them.

New SDL Perl site

Also we have begin work on a new site. It is still needs work. New Site.

--yapgh


\ 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