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La potencia de JavaScript en un 1Kb.

sin comentarios, faltaría plus, venga haz el tuyo pinchando aquí que esto tiene premio seguro!

Impresionante es lo que podemos ver y tocar en la “1K” donde se celebra el concurso de “demos técnicas” realizadas en y cuya premisa es que no superen un KA.

Hay de todo y muchas de ellas son excelentes, incluso un de ajedrez y un de plataformas estilo Mario, entrañable personaje videojuegil que ayer cumplió 25 años, todas estas demos están metidas en tan sólo 1Kb. de memoria.

Parece increíble, aunque amigos… no quisiera yo contar la historia de cuando antes de jugar me cascaba ochenta y pico líneas de código Basic a pelo, porque no existían pendrives ni discos duros ni siquiera disquettes o unidades de cassete en aquel venerable Sinclair ZX81 de exactamente 1Kb. de memoria y eso sin contar que la teclas que tenía eran duras, duras, planas con un sistema de membrana con sonido de rana… que tiempos!

¿Así que, a qué esperas para alucinar? http://js1k.com/demos

Por si fuera poco la visita de ese enlace os copypasteamos a continuación el código del juego de plataformas que hemos comentado, eso sí, para un mayor entendimiento os lo mosstramos sin comprimir y comentado, es decir ocupa más de una KA, es una long version ideal para aquellos que ven en el JavaScript el lenguaje de las videoconsolas del futuro, es decir, de las PlayStation 4 parriba… 😉 :

canvas=document.body.children[0];
screen_height=time=150;
last_height=screen_width=canvas.width=800;
unit=dead=50;
heights=[];

// The abbreviation loop, initializing the variabled needed by the key-handlers on the side.
for(prop in context=canvas.getContext('2d'))
  context[prop[jump=speed_x=speed_y=0]+(prop[6]||'')]=context[prop];

setInterval(function(){
  if(dead)
    // initialize the player position, score, and heightmap
    for(x=405,i=y=score=0;i<1e4;)
      // (screen_width is reused as the off-the-screen height of gap blocks)

      // a block can be a gap if its index is <9, or if the last block was no gap. after this test,
      // a random number is compared to .3 to determine whether an actual gap is generated, or a
      // regular random height.
      last_height=heights[i++]=
        i<9|last_height<screen_width&Math.random()<.3?screen_width:Math.random()*unit+80|0;

  // silly formula to create parabolic movement based on the time
  plant_pos=++time%99-unit;plant_pos=plant_pos*plant_pos/8+20;

  y+=speed_y;
  // only move horizontally if that doesn't take us deep underground (x/unit|0 fetches the index of
  // the block below an x coordinate)
  x+=y-heights[(x+speed_x)/unit|0]>9?0:speed_x;
  // compute final player height index, and ground level under it
  ground=heights[player_index=x/unit|0];
  // adjust y and speed_y based on whether we are on the ground or not
  speed_y=y<ground|speed_y<0?speed_y+1:(y=ground,jump?-10:0);

  // we'll need the context a lot
  with(context){
    A=function(color,x,y,radius){
      // a is the abbreviated form of arc
      radius&&a(x,y,radius,0,7,0);
      // if color is not a gradient object (we set a P property in gradient objects), it is an index
      // into a set of colors
      fillStyle=color.P?color:'#'+'ceff99ff78f86eeaaffffd45333'.substr(color*3,3);
      // f for fill, ba for beginPath
      f(); ba();
    };

    // now loop over visible, or close to visible, blocks, and draw them and their clouds
    for(dead=i=0;i<21;i++){
      // this loop is reused for drawing the background/rainbow, which consists of seven concentric
      // circles. there's no good reason why interleaving clearing the screen with drawing the
      // screen's contents should work, but in this case it does
      i<7&&A(i%6,screen_width/2,235,i?250-15*i:screen_width);

      // we start drawing 5 units in front of the player (first four will be off-screen, needed just
      // for clouds)
      height_index=player_index-5+i;

      scroll_pos=x-height_index*unit;
      // since player screen position is fixed, we can use scroll position for collision detection.
      // this variable indicates whether the player is in the 'middle' of the current block
      player_in_middle=scroll_pos>9&scroll_pos<41;

      // ta for translate. move to start of block to make other drawing commands shorter
      ta(unit-scroll_pos,0);
      // cL for createLinearGradient, for the ground/grass gradient
      gradient=cL(0,height=heights[height_index],0,height+9);
      // if height is divisible by 6, there's a coin here. draw it. if the player is standing on the
      // ground, in the middle of this unit, pick up the coin
      height%6||(A(2,25,height-7,5),y^ground||player_in_middle&&(heights[height_index]-=.1,score++));

      // abbreviate, since we need this twice (and use it again to test whether a value passed to A
      // is a gradient)
      gradient.P=gradient.addColorStop;
      // this implements sinky terrain---when the index is divisible by 7, we use a different color,
      // and do the sinking if the player is standing here
      gradient.P(0,height_index%7?'#5e1':(height_index^player_index||y^height||
                                          (y=heights[height_index]+=plant_pos/99),'#a59'));
      // brown earth color for the bottom of the gradient
      gradient.P(1,'#b93');

      // this draws the clouds
      height_index%4&&A(6,time/2%200,9,height_index%2?27:33);

      // draws the terrain block. m is moveTo, qt is quadraticCurveTo, l is lineTo
      m(-6,screen_height);qt(-6,height,3,height);l(47,height);qt(56,height,56,screen_height);A(gradient);

      // draw deco trees or piranha plant (height==screen_width for gap blocks), check for collision
      // with plant
      height_index%3?0:height<screen_width
        ?(A(gradient,33,height-15,10),fc(31,height-7,4,9))
        :(A(7,25,plant_pos,9),A(3,25,plant_pos,5),fc(24,plant_pos,2,screen_height),
          dead=player_in_middle&y>plant_pos-9?1:dead);

      // undo block-local translation
      ta(scroll_pos-unit,0)
    }

    // draws the player, using the speed to adjust the position of the iris
    A(6,unit,y-9,11);
    A(5,iris_x=unit+speed_x*.7,iris_y=y-9+speed_y/5,8);
    A(8,iris_x,iris_y,5);

    // color is already dark from eye pupil, draw score with this color
    fx(score+'¢',5,15)
  }

  // check whether the player has fallen off the screen
  dead=y>screen_height?1:dead
},unit);

onkeydown=onkeyup=function(e){
  // if this is a keydown event, new_val gets the value 4, otherwise 0
  new_val=e.type[5]?4:0;
  e=e.keyCode;

  // give jump a truthy value if up was pressed, falsy if up was released
  jump=e^38?jump:new_val;

  // similar for speed_x, inverting new_val if left is pressed
  speed_x=e^37?e^39?speed_x:new_val:-new_val
}
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Escrito por un tal uvedobles.com

September 14th, 2010 a las 7:32 am

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