c=document.body.children[0];h=t=150;L=w=c.width=800;u=D=50;H=[];R=Math.random;for($ in C=c.getContext('2d'))C[$[J=X=Y=0]+($[6]||'')]=C[$];setInterval("if(D)for(x=405,i=y=I=0;i<1e4;)L=H[i++]=i<9|L<w&R()<.3?w:R()*u+80|0;$=++t%99-u;$=$*$/8+20;y+=Y;x+=y-H[(x+X)/u|0]>9?0:X;j=H[o=x/u|0];Y=y<j|Y<0?Y+1:(y=j,J?-10:0);with(C){A=function(c,x,y,r){r&&a(x,y,r,0,7,0);fillStyle=c.P?c:'#'+'ceff99ff78f86eeaaffffd45333'.substr(c*3,3);f();ba()};for(D=Z=0;Z<21;Z++){Z<7&&A(Z%6,w/2,235,Z?250-15*Z:w);i=o-5+Z;S=x-i*u;B=S>9&S<41;ta(u-S,0);G=cL(0,T=H[i],0,T+9);T%6||(A(2,25,T-7,5),y^j||B&&(H[i]-=.1,I++));G.P=G.addColorStop;G.P(0,i%7?'#7e3':(i^o||y^T||(y=H[i]+=$/99),'#c7a'));G.P(1,'#ca6');i%4&&A(6,t/2%200,9,i%2?27:33);m(-6,h);qt(-6,T,3,T);l(47,T);qt(56,T,56,h);A(G);i%3?0:T<w?(A(G,33,T-15,10),fc(31,T-7,4,9)):(A(7,25,$,9),A(G,25,$,5),fc(24,$,2,h),D=B&y>$-9?1:D);ta(S-u,0)}A(6,u,y-9,11);A(5,M=u+X*.7,Q=y-9+Y/5,8);A(8,M,Q,5);fx(I+'¢',5,15)}D=y>h?1:D",u);onkeydown=onkeyup=function(e){E=e.type[5]?4:0;e=e.keyCode;J=e^38?J:E;X=e^37?e^39?X:E:-E}
// see http://marijn.haverbeke.nl/js1k.html for more context
// 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
}
