-SDL RC 2.5 decides to play with PDL +Introducing SDLx::Controller::Object, with our good friend Mario!
-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
+ Hi Folks
+This past week I have been working on making interfacing physics with SDL rendering a lot easier. The idea was to provide the user a callback to describe the acceleration of their object in the X, Y axis and Rotation. Using this idea I have completed a preliminary work for SDLx::Controller::Object. The demo below shows an example that was made with it. The SDLx* code is available at http://github.com/kthakore/SDL_perl and demo code is available at http://github.com/kthakore/scroller.
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-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.
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-First lets get the right modules.
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-Suppose you want a surface of size (200,400) and 32 bit (RGBA).
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-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;
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-Create a normal $piddle with zeros, byte format and the Bpp x width x height dimensions.
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-Here is where we get the acutal data the piddle is pointing to. We will have SDL create a new surface from this function.
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-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.
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-Finally make sure that the surface acutally has the correct dimensions we gave.
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-NOTE: $surface->format->BytesPerPixel must return 1,2,3,4. !!
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-Now you can blit and use the surface as needed; and do PDL operations as required.
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-To make sure SDL is in sync with the data. You must call SDL::Video::lock before doing PDL operations on the piddle.
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-After that you can unlock the surface to blit.
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-When blitting the new surface check for the return value to see if there has been a problem.
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-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.
-
-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
+ Hi Folks
+This past week I have been working on making interfacing physics with SDL rendering a lot easier. The idea was to provide the user a callback to describe the acceleration of their object in the X, Y axis and Rotation. Using this idea I have completed a preliminary work for SDLx::Controller::Object. The demo below shows an example that was made with it. The SDLx* code is available at http://github.com/kthakore/SDL_perl and demo code is available at http://github.com/kthakore/scroller.
-
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;
-
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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.
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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.
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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.
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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: $surface->format->BytesPerPixel must return 1,2,3,4. !!
-
-Now you can blit and use the surface as needed; and do PDL operations as required.
-
-
Operating on the Surface safely
-To make sure SDL is in sync with the data. You must call SDL::Video::lock before doing PDL operations on the piddle.
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SDL::Video::lock_surface($surface); - - $piddle ( :, 0 : rand(400), 0 : rand(200) ) .= pdl( rand(225), rand(225), rand(255), 255 ); -
-After that you can unlock the surface to blit.
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SDL::Video::unlock_surface($surface); -
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Errors due to BPP at blitting
-When blitting the new surface check for the return value to see if there has been a problem.
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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.
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