-Getting people to use SDL Perl: Docs, API, and Distribution +Providing direct memory access to SDL_Surface's pixels
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-Things have been busy but fruitful. Our two core modules are getting to be a bit more stable. Alien::SDL 1.405 is behaving well. This foundational stability will start to show results in SDL too I believe. Most excitingly the main developer of frozen-bubble is reviewing our Games::FrozenBubble port to CPAN. All good and well, but to keep this project going we need to improve.
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-After a long chat with a new SDL user on #sdl today, I realize we still have some way to go. Currently it seems we are lacking in a few areas. We can definitely use some feedback and help in these areas.
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-API sweetness
+ return sv; //make a modifiable reference using u_ptr's place as the memory :)
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+
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+
+
+Distribution
+my $green = pack 'b*', '11111111000000000000000000000000';
+substr( $surf32_matrix->[0][0], 0, 8 * 4, $green); #no change
+#substr( $surf32_matrix->[0][0], 0, 8 * 4, 0xFF000000); segfault
+substr( ${$surf32_matrix->[0][0]}, 0, 8 * 4, 0xFF000000); #no change
+#$surf32_matrix->[0][0] = $green; SEGFAULT's cannot write to memory
+${$surf32_matrix->[0][0]} = $green; #no change
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The road so far
-Things have been busy but fruitful. Our two core modules are getting to be a bit more stable. Alien::SDL 1.405 is behaving well. This foundational stability will start to show results in SDL too I believe. Most excitingly the main developer of frozen-bubble is reviewing our Games::FrozenBubble port to CPAN. All good and well, but to keep this project going we need to improve.
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-
Getting people to use SDL Perl
-After a long chat with a new SDL user on #sdl today, I realize we still have some way to go. Currently it seems we are lacking in a few areas. We can definitely use some feedback and help in these areas.
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- Tutorials/Documentation
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+
In an attempt to make pixel access easier on SDL_Surface pixels. I have started work on SDLx::Surface. So far I have only start on the 32 bpp surfaces.
+
The general idea is to make Pointer Values (PV) of each pixel in the surface and place them into a 2D matrix. First I make pointer values like this:
+
SV * get_pixel32 (SDL_Surface *surface, int x, int y) +{ + //Convert the pixels to 32 bit + Uint32 *pixels = (Uint32 *)surface->pixels; + + //Get the requested pixel + Uint32* u_ptr = pixels + ( y * surface->w ) + x ; -
- We have more docs now on http://sdl.perl.org but they suck -
- What type of tutorials do you think will be good for beginners? + SV* sv = newSVpv("a",1); //Make a temp SV* value on the go + SvCUR_set(sv, sizeof(Uint32)); //Specify the new CUR length + SvLEN_set(sv, sizeof(Uint32)); //Specify the LEN length + SvPV_set(sv,(char*)u_ptr); // set the actual pixel's pointer as the memory space to use -
- A project start to finish? -
- Individual tutorials for various topics? -
- What needs to go in SDL::CookBook? -
- SDL Perl depends on distinct C libraries +} +
+
Next I loop through all the pixels and put them in a 2D array format, shown below:
AV * construct_p_matrix ( SDL_Surface *surface ) +{ + AV * matrix = newAV(); + int i, j; + for( i =0 ; i < surface->w; i++) + { + AV * matrix_row = newAV(); + for( j =0 ; j < surface->h; j++) + { + av_push(matrix_row, get_pixel32(surface, i,j) ); + } + av_push(matrix, newRV_noinc((SV*) matrix_row) ); + } + + return matrix; +} +
+
You can see the complete here.
+
In Perl I can do a get access on this pixel using:
+
+
my $surf32_matrix = SDLx::Surface::pixel_array($screen_surface); + print unpack 'b*', $surf32_matrix->[0][0]; # pixel value at x = 0 and y =0 +#OUTPUT: +# 11111111000000000000000000000000 +
+
The structure of the PV is using Devel::Peek is :
+
print Dump $surf32_matrix->[0][0]; +#OUTPUT: +#SV = PV(0xed0dbc) at 0xeb5344 +# REFCNT = 1 +# FLAGS = (POK,pPOK) +# PV = 0x9e04ac "\0\0\377\0" +# CUR = 4 +# LEN = 4 +
+
The problem is in setting the value of this pointer value. I have tried the following things with no success:
+
if ( SDL::Video::MUSTLOCK($screen_surface) ) { + return if ( SDL::Video::lock_surface($screen_surface) < 0 ); #required for pixel operations +} -
- This makes naming conventions, data formats different the SDL:: namespaces -
- How do people design this stuff? +#USING pack -
- We are hackers and we just go do stuff but I think this needs some prior thought -
- Any takers? -
- If SDL scripts can be packaged up simply for game developers to distribute their games it will be a big plus -
- One way is a Wx::Perl::Packer clone -
- Another is a CPAN/Steam clone that game devs can upload games too and people can point and click download games? -
If anyone wants to help in these areas please talk to us on sdl-devel@perl.org.
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