1SDL::Cookbook::PDL(3) User Contributed Perl DocumentationSDL::Cookbook::PDL(3)
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NAME

6       SDL::CookBook::PDL -- CookBook for SDL + PDL
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8       PDL provides great number crunching capabilities to Perl and SDL
9       provides game-developer quality real-time bitmapping and sound.  You
10       can use PDL and SDL ''together'' to create real-time, responsive
11       animations and simulations.  In this section we will go through the
12       pleasures and pitfalls of working with both powerhouse libraries.
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14   CATEGORY
15       Cookbook
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Creating a SDL Surface piddle

18       PDL's core type is a piddle. Once a piddle is provided to PDL it can go
19       do a numerous amounts of things. Please see the example in
20       'examples/cookbook/pdl.pl' that came with this module.
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22   Creating a simple piddle
23       First lets get the right modules.
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25         use PDL;
26         use SDL::Rect;
27         use SDL::Video;
28         use SDL::Surface;
29         use SDL::PixelFormat;
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31       Suppose you want a surface of size (200,400) and 32 bit (RGBA).
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33          my ( $bytes_per_pixel, $width, $height ) = ( 4, 200, 400 );
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35       Define the $width, $height and $bytes_per_pixel. Your $bytes_per_pixel
36       is the number of bits (in this case 32) divided by 8 bits per byte.
37       Therefore for our 32 bpp we have 4 Bpp;
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39          my $piddle  = zeros( byte, $bytes_per_pixel, $width, $height );
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41       Create a normal $piddle with zeros, byte format and the Bpp x width x
42       height dimensions.
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44          my $pointer = $piddle->get_dataref();
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46       Here is where we get the actual data the piddle is pointing to. We will
47       have SDL create a new surface from this function.
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49          my $surface = SDL::Surface->new_from( $pointer, $width, $height, 32,
50               $width * $bytes_per_pixel );
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52       Using the same dimensions we create the surface using new_form. The
53       width *  Bpp is the scanline (pitch) of the surface in bytes.
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55          warn "Made surface of $width, $height and ". $surface->format->BytesPerPixel;
56          return ( $piddle, $surface );
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58       Finally make sure that the surface actually has the correct dimensions
59       we gave.
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61       NOTE: $surface->format->BytesPerPixel must return 1,2,3,4. !!
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63       Now you can blit and use the surface as needed; and do PDL operations
64       as required.
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66   Operating on the Surface safely
67       To make sure SDL is in sync with the data. You must call
68       SDL::Video::lock before doing PDL operations on the piddle.
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70           SDL::Video::lock_surface($surface);
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72           $piddle->mslice( 'X', [ rand(400), rand(400), 1 ], [ rand(200), rand(200), 1 ] )
73               .= pdl( rand(225), rand(225), rand(255), 255 );
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75       After that you can unlock the surface to blit.
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77           SDL::Video::unlock_surface($surface);
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79   Error due to BPP at blitting
80       When blitting the new surface check for the return value to see if
81       there has been a problem.
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83           my $b = SDL::Video::blit_surface(
84               $surface,  SDL::Rect->new( 0, 0, $surface->w, $surface->h ),
85               $app, SDL::Rect->new(  ( $app->w - $surface->w ) / 2, ( $app->h - $surface->h ) / 2, $app->w, $app->h )
86              );
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88           die "Could not blit: " . SDL::get_error() if ( $b == -1 );
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90       If the error message is 'Blit combination not supported' that means
91       that the BPP is incorrect or inconsistent with the dimensions.  After
92       that a simple update_rect will so your new surface on the screen.
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AUTHORS

95       See "AUTHORS" in SDL.
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99perl v5.30.1                      2020-01-30             SDL::Cookbook::PDL(3)
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