diff --git a/contents/flood_fill/code/javascript/flood_fill.js b/contents/flood_fill/code/javascript/flood_fill.js new file mode 100644 index 000000000..8180869ab --- /dev/null +++ b/contents/flood_fill/code/javascript/flood_fill.js @@ -0,0 +1,101 @@ +// This is a p5.js sketch. +// https://p5js.org + +function isInBounds(x, y) { + return (x >= 0) && (x < width) && (y >= 0) && (y < height) +} + +function isColor(x, y, color) { + const index = (x + y * width) * 4 + return pixels[index] == red(color) && + pixels[index + 1] == green(color) && + pixels[index + 2] == blue(color) && + pixels[index + 3] == alpha(color) +} + +function recolorPixel(x, y, oldColor, newColor) { + const index = (x + y * width) * 4 + pixels[index] = red(newColor) + pixels[index + 1] = green(newColor) + pixels[index + 2] = blue(newColor) + pixels[index + 3] = alpha(newColor) +} + +function findNeighbors(x, y, oldColor) { + const allNeighbors = [ + [x, y - 1], // North + [x + 1, y], // East + [x, y + 1], // South + [x - 1, y] // West + ] + + return allNeighbors + .filter(loc => isInBounds(...loc)) + .filter(loc => isColor(...loc, oldColor)) +} + +function stackFill(x, y, oldColor, newColor) { + const stack = [ + [x, y] + ] + + while (stack.length > 0) { + const currentLoc = stack.pop() + recolorPixel(...currentLoc, oldColor, newColor) + + for (const n of findNeighbors(...currentLoc, oldColor)) + stack.push(n) + } +} + +function queueFill(x, y, oldColor, newColor) { + const queue = [ + [x, y] + ] + + while (queue.length > 0) { + const currentLoc = queue.shift() + recolorPixel(...currentLoc, oldColor, newColor) + + for (const n of findNeighbors(...currentLoc, oldColor)) { + // Color neighbor pixel before enqueuing to prevent + // it from being colored multiple times + recolorPixel(...n, oldColor, newColor) + queue.push(n) + } + } +} + +function recursiveFill(x, y, oldColor, newColor) { + recolorPixel(x, y, oldColor, newColor) + + for (const n of findNeighbors(x, y, oldColor)) + recursiveFill(...n, oldColor, newColor) +} + +function setup() { + createCanvas(600, 200); + noLoop() +} + +function draw() { + const bgColor = color(0, 0, 0, 0) + background(bgColor); + + noFill() + stroke(0) + strokeWeight(3) + triangle(80, 80, 160, 100, 100, 140) + triangle(340, 30, 380, 170, 230, 120) + triangle(480, 40, 580, 140, 430, 160) + + loadPixels() + + // recursiveFill tends to blow up the stack for large + // areas so it gets a smaller triangle + recursiveFill(100, 100, bgColor, color(30, 245, 250)) + stackFill(300, 100, bgColor, color(130, 50, 180)) + queueFill(500, 100, bgColor, color(50, 255, 225)) + + updatePixels() +} \ No newline at end of file diff --git a/contents/flood_fill/flood_fill.md b/contents/flood_fill/flood_fill.md index 836f86897..07a0c727e 100644 --- a/contents/flood_fill/flood_fill.md +++ b/contents/flood_fill/flood_fill.md @@ -90,6 +90,8 @@ In code, this might look like this: [import:37-55, lang:"julia"](code/julia/flood_fill.jl) {% sample lang="c" %} [import:34-52, lang:"c"](code/c/flood_fill.c) +{% sample lang="js" %} +[import:24-35, lang:"javascript"](code/javascript/flood_fill.js) {% endmethod %} @@ -106,15 +108,8 @@ In code, it might look like this: [import:106-118, lang:"julia"](code/julia/flood_fill.jl) {% sample lang="c" %} [import:180-195, lang:"c"](code/c/flood_fill.c) -{% endmethod %} - -All code snippets for this chapter rely on an exterior `color` function, defined as - -{% method %} -{% sample lang="jl" %} -[import:23-35, lang:"julia"](code/julia/flood_fill.jl) -{% sample lang="c" %} -[import:28-32, lang:"c"](code/c/flood_fill.c) +{% sample lang="js" %} +[import:69-74, lang:"javascript"](code/javascript/flood_fill.js) {% endmethod %} The above code continues recursing through available neighbors as long as neighbors exist, and this should work so long as we are adding the correct set of neighbors. @@ -126,6 +121,8 @@ Additionally, it is possible to do the same type of traversal by managing a stac [import:57-77, lang:"julia"](code/julia/flood_fill.jl) {% sample lang="c" %} [import:85-108, lang:"c"](code/c/flood_fill.c) +{% sample lang="js" %} +[import:37-49, lang:"javascript"](code/javascript/flood_fill.js) {% endmethod %} This is ultimately the same method of traversal as before; however, because we are managing our own data structure, there are a few distinct differences: @@ -165,6 +162,8 @@ The code would look something like this: [import:80-104, lang:"julia"](code/julia/flood_fill.jl) {% sample lang="c" %} [import:155-178, lang:"c"](code/c/flood_fill.c) +{% sample lang="js" %} +[import:51-67, lang:"javascript"](code/javascript/flood_fill.js) {% endmethod %} Now, there is a small trick in this code that must be considered to make sure it runs optimally. @@ -243,6 +242,8 @@ After, we will fill in the left-hand side of the array to be all ones by choosin [import, lang:"julia"](code/julia/flood_fill.jl) {% sample lang="c" %} [import, lang:"c"](code/c/flood_fill.c) +{% sample lang="js" %} +[import, lang:"javascript"](code/javascript/flood_fill.js) {% endmethod %}