Simplify reading of page

[rbdr/r.bdr.sh] / jekyll / js / breadsticks.js

// App Config

const kEntrypoint = "breadsticks";
const kGap = 50;
const kDrawDelay = 100;
const kDarkDrawingColor = '#fff';
const kLightDrawingColor = '#000';

/***********************************************
 * Breadstick generates a matrix of points
 * and assigns a vector to each entry
 * and then draws them
 ***********************************************/

/*
 * Generate field of points in which to draw
 */

// Updates the field object using a canvas

const updateFieldFromCanvas = (field, canvas) => {
  updateFieldFromRect(field, canvas.getBoundingClientRect());

  canvas.width = window.innerWidth;
  canvas.height = window.innerHeight;

  window.addEventListener('resize', () => {
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
    updateFieldFromRect(field, canvas.getBoundingClientRect());
  });
};

// Updates a field object using a rect

const updateFieldFromRect = (field, rect) => {
  field.width = rect.width;
  field.height = rect.height;
}

/*
 * Generate the matrix of vectors
 */

// Updates a matrix for a given field using the mouse


const updateFieldMatrixFromMouse = (field, matrix, gap = 50) => {
  const mousePosition = {
    x: 0,
    y: 0
  };

  fillMatrix(matrix, mousePosition.x, mousePosition.y, field.width, field.height, gap);

  const updateMousePosition = document.addEventListener('mousemove', (event) => {
    mousePosition.x = event.offsetX;
    mousePosition.y = event.offsetY;
    fillMatrix(matrix, mousePosition.x, mousePosition.y, field.width, field.height, gap);
  });
};

// Gets a matrix by calculating the offset between position and field.

const fillMatrix = (matrix, x, y, w, h, gap = 50) => {
  for (let i = 0; i < w / gap; ++i) {
    matrix[i] = [];
    for (let j = 0; j < h / gap; ++j) {
      let targetX = i * gap;
      let targetY = j * gap;
      matrix[i][j] = calculateOffsetVector(x, y, targetX, targetY, w, h);
    }
  }
};

// Calculates the offset vector of a point
const calculateOffsetVector = (sourceX, sourceY, targetX, targetY, w, h) => {
  const xOffset = targetX - sourceX;
  const yOffset = targetY - sourceY;

  return {
    position: {
      x: targetX,
      y: targetY
    },
    angle: Math.atan2(xOffset, yOffset),
    magnitude: Math.sqrt(Math.pow(xOffset, 2) + Math.pow(yOffset, 2))
  };
};


/*
 * Drawing
 */

// draw a vector from center
const drawVector = (context, i, j, vector) => {
  const origin = {
    x: context.canvas.width  / 2,
    y: context.canvas.height / 2
  };
  const x = origin.x - vector.magnitude * Math.cos(vector.angle);
  const y = origin.y - vector.magnitude * Math.sin(vector.angle);
  context.beginPath();
  context.moveTo(vector.position.x, vector.position.y);
  context.lineTo(Math.round(x), Math.round(y));
  context.stroke();
};

// Gets the color depending on the team

const getColor = () => {
  if (window.matchMedia('(prefers-color-scheme: dark)').matches) {
    return kDarkDrawingColor;
  }

  return kLightDrawingColor;
};


// Draws field on canvas

const drawFieldMatrixOnCanvas = (matrix, context) => {

  context.strokeStyle = getColor();
  context.clearRect(0, 0, context.canvas.width, context.canvas.height);

  for (let i = 0; i < matrix.length; ++i) {
    const row = matrix[i];
    for (let j = 0; j < row.length; ++j) {
      const vector = row[j]

      if (vector) {
        drawVector(context, i, j, vector);
      }
    }
  }
};

/*
 * Entrypoint
 */

const run = () => {

  const field = {
    width: 0,
    height: 0
  };
  const canvas = document.getElementById(kEntrypoint);

  updateFieldFromCanvas(field, canvas);

  const matrix = [[]];
  updateFieldMatrixFromMouse(field, matrix, kGap);

  const context = canvas.getContext('2d');
  const drawFunction = () => {
    drawFieldMatrixOnCanvas(matrix, context);
    setTimeout(drawFunction, kDrawDelay);
  }

  setTimeout(drawFunction, 0);
};

window.addEventListener('load', run);