pods::...k::PDL(3pm)

💖 NAME 💖

okay bestie, welcome to SDL::CookBook::PDL — the CookBook for SDL + PDL. This page comes from the User Contributed Perl Documentation and its page name is pods::...k::PDL(3pm). ✨

PDL is literally the number-crunching queen for Perl, and SDL serves up game-developer-quality real-time bitmapping and sound. 🎮✨ You can use PDL and SDL ''together'' to make real-time, responsive animations and simulations — yes, both powerhouse libraries in one vibe. slay. In this section we’re gonna go through the pleasures and the pitfalls of working with both powerhouse libraries. No gatekeeping. 💅

🍓 CATEGORY 🍓

Cookbook. periodt. 📚

🌸 Creating a SDL Surface piddle 🌸

PDL’s core type is a piddle. Once you hand a piddle to PDL, it can go do a numerous amounts of things. 🫶 Please see the example in 'examples/cookbook/pdl.pl' that came with this module. 🔍

🎀 Creating a simple piddle 🎀

First, let’s 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 actual 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 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 actually has the correct dimensions we gave. 👀

NOTE: $surface->format->BytesPerPixel must return 1, 2, 3, 4. !! No cap, this one matters. 💀

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->mslice( 'X', [ rand(400), rand(400), 1 ], [ rand(200), rand(200), 1 ] )
    .= pdl( rand(225), rand(225), rand(255), 255 );

After that you can unlock the surface to blit. 🔓

SDL::Video::unlock_surface($surface);

🔥 Error due to BPP at blitting 🔥

When blitting the new surface, check 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 inconsistent with the dimensions. Danger zone, bestie. 💀 After that a simple update_rect will so your new surface on the screen. 🖥️✨

👑 AUTHORS 👑

See "AUTHORS" in SDL.

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okay bye bestie 💅 mwah! This page is from perl v5.42.0, dated 2024-05-01, and it’s the pods::...k::PDL(3pm) page. Stay slay, keep your piddles safe, and don’t forget to unlock your surface. 🫶✨