## ----setup, include = FALSE---------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  eval = FALSE
)

## ----va-engine, echo = FALSE, results = "asis", eval = TRUE-------------------
cat("<script>\n", paste(readLines("va-engine.js"), collapse = "\n"), "\n</script>\n", sep = "")

## -----------------------------------------------------------------------------
# library(vectra)

## ----raster-to-points-anim, echo = FALSE, results = "asis", eval = TRUE-------
body <- "
var s=VA.setup('m2p-cv'); if(!s)return; var x=s.ctx,W=s.w,H=s.h,C=VA.C;
var GX=26,GY=72,COLS=8,ROWS=5,TW=50,TH=50,GW=COLS*TW,GH=ROWS*TH;
var N=COLS*ROWS;
var LX=GX+GW+70, LY=86, RH=15;
var seed=20260625;function rnd(){seed=(seed*1103515245+12345)&0x7fffffff;return seed/0x7fffffff;}
var V=[];for(var i=0;i<N;i++){V.push(VA.clamp(0.18+0.62*((i%COLS)/(COLS-1))+0.18*(rnd()-0.5),0,1));}
var PER=0.42, PERIOD=N*PER+1.8;
function cell(i){var c=i%COLS,r=Math.floor(i/COLS);return {c:c,r:r,cx:GX+c*TW+TW/2,cy:GY+r*TH+TH/2};}
function draw(tc){VA.bg(x,W,H);
  VA.title(x,'A raster read as one row per cell');
  var done=Math.min(Math.floor(tc/PER),N);
  for(var i=0;i<N;i++){var p=cell(i);var lit=i<done;
    x.fillStyle=lit?VA.A(C.green,(0.22+0.62*V[i]).toFixed(3)):C.off;
    x.fillRect(p.cx-TW/2+2,p.cy-TH/2+2,TW-4,TH-4);
    x.strokeStyle=C.grid;x.strokeRect(p.cx-TW/2+2,p.cy-TH/2+2,TW-4,TH-4);}
  if(done<N){var pc=cell(done);var f=(tc/PER)-done;
    x.strokeStyle=C.amber;x.lineWidth=2;x.strokeRect(pc.cx-TW/2+2,pc.cy-TH/2+2,TW-4,TH-4);x.lineWidth=1;
    var ty=LY+Math.min(done,15)*RH;
    var tx=VA.lerp(pc.cx,LX-12,VA.easeOut(f)),tyy=VA.lerp(pc.cy,ty,VA.easeOut(f));
    x.fillStyle=C.green;x.beginPath();x.arc(tx,tyy,4,0,6.2832);x.fill();}
  x.fillStyle=C.cyan;x.font=VA.F(12,true);x.textAlign='left';x.fillText('x     y     value',LX,LY-16);
  x.strokeStyle=C.grid;x.beginPath();x.moveTo(LX,LY-9);x.lineTo(W-16,LY-9);x.stroke();
  var show=Math.min(done,15);
  for(var k=0;k<show;k++){var idx=done-show+k;if(idx<0)continue;var p2=cell(idx);
    x.fillStyle=C.ink;x.font=VA.F(11);x.textAlign='left';
    x.fillText(p2.c+'     '+(ROWS-1-p2.r)+'     '+V[idx].toFixed(2),LX,LY+6+k*RH);}
  x.fillStyle=C.mut;x.font=VA.F(11);x.textAlign='left';x.fillText(done+' / '+N+' cells read',LX,H-18);
}
VA.run(draw,PERIOD,null,'m2p','m2p-cv');
"
cat(paste0(
  "<canvas id='m2p-cv' width='760' height='372' style='max-width:100%'></canvas>\n",
  "<script>\n(function(){\n", body, "\n})();\n</script>\n"))

## -----------------------------------------------------------------------------
# clim <- vec_open_raster("worldclim_bio.vec")
# 
# occ <- read.csv("occurrences.csv")          # species, x, y
# occ <- cbind(occ, vec_extract_points(clim, occ$x, occ$y))
# head(occ)

## ----select-by-location-anim, echo = FALSE, results = "asis", eval = TRUE-----
body <- "
var s=VA.setup('sbl-cv'); if(!s)return; var x=s.ctx,W=s.w,H=s.h,C=VA.C;
var PER=9.5,HOLD=2.0,PERIOD=PER+HOLD;
var poly=[[330,128],[470,116],[548,214],[472,322],[332,332],[262,216]];
var seed=77;function rnd(){seed=(seed*1103515245+12345)&0x7fffffff;return seed/0x7fffffff;}
var P=[];for(var i=0;i<56;i++){P.push([60+rnd()*(W-120),64+rnd()*(H-118)]);}
P.sort(function(a,b){return a[0]-b[0];});
function inPoly(px,py){var inside=false;for(var i=0,j=poly.length-1;i<poly.length;j=i++){var xi=poly[i][0],yi=poly[i][1],xj=poly[j][0],yj=poly[j][1];var hit=((yi>py)!=(yj>py))&&(px<(xj-xi)*(py-yi)/(yj-yi)+xi);if(hit)inside=!inside;}return inside;}
function drawPoly(){x.save();x.strokeStyle=C.amber;x.lineWidth=2;x.beginPath();x.moveTo(poly[0][0],poly[0][1]);for(var i=1;i<poly.length;i++)x.lineTo(poly[i][0],poly[i][1]);x.closePath();x.stroke();x.fillStyle=VA.A(C.amber,0.09);x.fill();x.restore();}
function draw(tc){VA.bg(x,W,H);
  VA.title(x,'Select by location');
  drawPoly();
  x.fillStyle=C.amber;x.font=VA.F(12,true);x.textAlign='center';x.fillText('study region',405,222);
  var sweep=VA.clamp(tc/PER,0,1)*W;
  var kept=0,seen=0;
  for(var i=0;i<P.length;i++){var px=P[i][0],py=P[i][1];var reached=px<=sweep;var ins=inPoly(px,py);
    if(reached){seen++;if(ins)kept++;}
    var col,a;
    if(!reached){col=C.mut;a=0.5;} else if(ins){col=C.green;a=1;} else {col=C.red;a=0.26;}
    x.globalAlpha=a;x.fillStyle=col;x.beginPath();x.arc(px,py,4.2,0,6.2832);x.fill();x.globalAlpha=1;}
  if(tc<PER){x.strokeStyle=C.cyan;x.lineWidth=2;x.beginPath();x.moveTo(sweep,46);x.lineTo(sweep,H-34);x.stroke();x.lineWidth=1;}
  x.fillStyle=C.green;x.font=VA.F(13,true);x.textAlign='left';x.fillText('kept '+kept,16,H-20);
  x.fillStyle=C.red;x.fillText('dropped '+(seen-kept),110,H-20);
  x.fillStyle=C.mut;x.font=VA.F(11);x.textAlign='right';x.fillText('spatial_filter(points, region)',W-16,H-18);
}
VA.run(draw,PERIOD,null,'sbl','sbl-cv');
"
cat(paste0(
  "<canvas id='sbl-cv' width='760' height='400' style='max-width:100%'></canvas>\n",
  "<script>\n(function(){\n", body, "\n})();\n</script>\n"))

## -----------------------------------------------------------------------------
# region <- sf::st_read("study_area.gpkg", quiet = TRUE)
# 
# inside <- tbl("occurrences.vtr") |>
#   spatial_filter(region, coords = c("x", "y"), crs = 4326)

## -----------------------------------------------------------------------------
# clipped <- tbl("rivers.vtr") |> spatial_clip(region, crs = 4326)

## -----------------------------------------------------------------------------
# tagged <- tbl("gbif_points.vtr") |>
#   spatial_join(tbl("countries.vtr"), coords = c("x", "y"),
#                crs = 4326, partition = grid(1))

## ----rasterize-anim, echo = FALSE, results = "asis", eval = TRUE--------------
body <- "
var s=VA.setup('rz-cv'); if(!s)return; var x=s.ctx,W=s.w,H=s.h,C=VA.C;
var GX=44,GW=W-88,COLS=16,ROWS=8,TW=GW/COLS,GY=128,TH=27,GH=ROWS*TH;
var PERIOD=14.0,FALL=0.9;
var seed=531;function rnd(){seed=(seed*1103515245+12345)&0x7fffffff;return seed/0x7fffffff;}
var D=[];var cxC=10.5,cyC=4.5;
for(var i=0;i<150;i++){var c=Math.round(VA.clamp(cxC+(rnd()-0.5)*9+(rnd()-0.5)*5,0,COLS-1));var r=Math.round(VA.clamp(cyC+(rnd()-0.5)*5+(rnd()-0.5)*3,0,ROWS-1));D.push([c,r,rnd()]);}
function draw(tc){VA.bg(x,W,H);
  VA.title(x,'Rasterize: points to a density grid');
  var cnt=new Array(COLS*ROWS).fill(0),maxc=1;
  for(var i=0;i<D.length;i++){var rt=D[i][2]*PERIOD*0.82;if(tc>=rt+FALL){var k=D[i][1]*COLS+D[i][0];cnt[k]++;if(cnt[k]>maxc)maxc=cnt[k];}}
  for(var r=0;r<ROWS;r++)for(var c=0;c<COLS;c++){var k=r*COLS+c;var v=cnt[k]/maxc;
    x.fillStyle=v>0?VA.A(C.cyan,(0.14+0.78*v).toFixed(3)):C.off;
    x.fillRect(GX+c*TW+1,GY+r*TH+1,TW-2,TH-2);}
  x.strokeStyle=C.grid;for(var c2=0;c2<=COLS;c2++){x.beginPath();x.moveTo(GX+c2*TW,GY);x.lineTo(GX+c2*TW,GY+GH);x.stroke();}
  for(var r2=0;r2<=ROWS;r2++){x.beginPath();x.moveTo(GX,GY+r2*TH);x.lineTo(GX+GW,GY+r2*TH);x.stroke();}
  for(var i=0;i<D.length;i++){var rt=D[i][2]*PERIOD*0.82;var fall=tc-rt;
    if(fall>=0&&fall<FALL){var f=fall/FALL;var tcx=GX+(D[i][0]+0.5)*TW,tcy=GY+(D[i][1]+0.5)*TH;var py=VA.lerp(62,tcy,VA.ease(f));
      x.fillStyle=C.green;x.globalAlpha=1-0.25*f;x.beginPath();x.arc(tcx,py,3.4,0,6.2832);x.fill();x.globalAlpha=1;}}
  x.fillStyle=C.cyan;x.font=VA.F(12,true);x.textAlign='right';x.fillText('brighter = more points per cell',W-16,GY-12);
  x.fillStyle=C.mut;x.font=VA.F(11);x.textAlign='left';x.fillText('one batch streams past; the grid stays resident',16,H-18);
}
VA.run(draw,PERIOD,null,'rz','rz-cv');
"
cat(paste0(
  "<canvas id='rz-cv' width='760' height='378' style='max-width:100%'></canvas>\n",
  "<script>\n(function(){\n", body, "\n})();\n</script>\n"))

## -----------------------------------------------------------------------------
# # Point density on a continental grid, streamed from a billion-row file.
# density <- tbl("gbif_points.vtr") |>
#   rasterize(extent = c(-180, -90, 180, 90), res = 0.1,
#             fun = "count", path = "density.vec")

## -----------------------------------------------------------------------------
# admin <- sf::st_read("regions.gpkg", quiet = TRUE)
# zonal(clim, admin, fun = c("mean", "sd"), zone_field = "region_id")

## -----------------------------------------------------------------------------
# terrain("dem.vec", v = c("slope", "aspect", "hillshade"),
#         path = "dem_derivatives.vec")

## -----------------------------------------------------------------------------
# warp("dem.vec", list(crs = 3035, res = 25),
#      method = "bilinear", path = "dem_laea.vec")

## -----------------------------------------------------------------------------
# habitat <- polygonize("landcover.vec")       # one polygon per class

## -----------------------------------------------------------------------------
# isolines <- contours("dem.vec", levels = seq(0, 3000, by = 200))

## -----------------------------------------------------------------------------
# study <- mask("dem.vec", region, path = "dem_study.vec")

## -----------------------------------------------------------------------------
# ndvi <- rast_calc(list(nir = "nir.vec", red = "red.vec"),
#                   (nir - red) / (nir + red), path = "ndvi.vec")

## -----------------------------------------------------------------------------
# tile_merge <- mosaic(list("n50.vec", "n51.vec", "n52.vec"), fun = "mean")

## -----------------------------------------------------------------------------
# dist_to_road <- proximity("roads.vec", path = "road_distance.vec")
# sea_distance <- proximity("landcover.vec", target = 0)   # 0 = water

## ----cost-tiers-anim, echo = FALSE, results = "asis", eval = TRUE-------------
body <- "
var s=VA.setup('ct-cv'); if(!s)return; var x=s.ctx,W=s.w,H=s.h,C=VA.C;
var PERIOD=12.0;
var rows=[
 {name:'monoid fold',sub:'spatial_filter, rasterize, zonal',col:'green',f:function(t){return 0.15+0.02*Math.sin(t*9);}},
 {name:'sort / partition',sub:'focal, terrain, warp, partitioned join',col:'amber',f:function(t){return 0.16+0.2*(0.5-0.5*Math.cos(t*6.5));}},
 {name:'all-to-all',sub:'self-overlay, voronoi, neighbour graphs',col:'red',f:function(t){return VA.clamp(t,0,1)*0.9+0.05;}}
];
var PX=310,PW=W-310-92,BH=56,GAP=36,TOP=74;
function draw(tc){VA.bg(x,W,H);
  VA.title(x,'Cost-model tiers: memory over a run');
  var t=tc/PERIOD;
  for(var i=0;i<3;i++){var y=TOP+i*(BH+GAP);var rw=rows[i];
    x.strokeStyle=C.red;x.setLineDash([5,4]);x.beginPath();x.moveTo(PX,y-7);x.lineTo(PX+PW,y-7);x.stroke();x.setLineDash([]);
    x.fillStyle=C.off;x.fillRect(PX,y,PW,BH);x.strokeStyle=C.grid;x.strokeRect(PX,y,PW,BH);
    var cursor=VA.ease(VA.clamp(t/0.98,0,1)),steps=Math.floor(cursor*PW);
    x.fillStyle=C[rw.col];x.globalAlpha=0.82;
    for(var px=0;px<steps;px++){var hv=VA.clamp(rw.f(px/PW),0,1);x.fillRect(PX+px,y+BH-hv*BH,1.4,hv*BH);}
    x.globalAlpha=1;
    if(cursor<1){var cx2=PX+steps;x.strokeStyle=C.cyan;x.beginPath();x.moveTo(cx2,y);x.lineTo(cx2,y+BH);x.stroke();}
    x.fillStyle=C[rw.col];x.font=VA.F(14,true);x.textAlign='right';x.fillText(rw.name,PX-14,y+24);
    x.fillStyle=C.mut;x.font=VA.F(9);x.fillText(rw.sub,PX-14,y+40);
    x.fillStyle=C.red;x.font=VA.F(10);x.textAlign='left';x.fillText('RAM',PX+PW+8,y-3);}
  x.fillStyle=C.mut;x.font=VA.F(11);x.textAlign='center';x.fillText('fold and partition stay under the RAM line; all-to-all reaches it',W/2,H-16);
}
VA.run(draw,PERIOD,null,'ct','ct-cv');
"
cat(paste0(
  "<canvas id='ct-cv' width='760' height='400' style='max-width:100%'></canvas>\n",
  "<script>\n(function(){\n", body, "\n})();\n</script>\n"))