boids/draw.mjs

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JavaScript
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import Vector from './vector.mjs';
const boidShape = [
new Vector(2, 0),
new Vector(-1, 1),
new Vector(-1, -1),
new Vector(2, 0),
];
const boidShapeSize = boidShape.length;
const transformed = new Vector(0, 0);
export const boids = (activeBoids, params, ctx, width, height, center) =>
{
const boidsSize = activeBoids.length;
ctx.clearRect(0, 0, width, height);
// // Draw each boids visibility and proximity zones
// ctx.beginPath();
// ctx.fillStyle = '#BBEE94';
// for (let boid of activeBoids)
// {
// const trans = boid.pos.add(center);
// ctx.moveTo(
// trans.x + params.visibleDist,
// trans.y
// );
// ctx.arc(
// trans.x, trans.y,
// params.visibleDist,
// 0, 2 * Math.PI
// );
// }
// ctx.fill();
// ctx.stroke();
// ctx.beginPath();
// ctx.fillStyle = '#EE9495';
// for (let boid of activeBoids)
// {
// const trans = boid.pos.add(center);
// ctx.moveTo(
// trans.x + params.closeDist,
// trans.y
// );
// ctx.arc(
// trans.x, trans.y,
// params.closeDist,
// 0, 2 * Math.PI
// );
// }
// ctx.fill();
// ctx.stroke();
// // Draw each boids velocity vector
// ctx.beginPath();
// ctx.strokeStyle = 'rgba(0, 0, 0, 0.5)';
// for (let boid of activeBoids)
// {
// const start = boid.pos.add(center);
// const end = start.add(boid.vel.mul(0.25));
// ctx.moveTo(start.x, start.y);
// ctx.lineTo(end.x, end.y);
// }
// ctx.stroke();
// Draw each boids head following the angle of its course
ctx.beginPath();
ctx.fillStyle = 'black';
for (let i = 0; i < boidsSize; ++i)
{
const boid = activeBoids[i];
const angle = boid.vel.angle();
let isFirst = true;
for (let j = 0; j < boidShapeSize; ++j)
{
transformed.x = boidShape[j].x;
transformed.y = boidShape[j].y;
transformed
.rotate(angle)
.mul(params.radius)
.add(center)
.add(boid.pos);
if (isFirst)
{
ctx.moveTo(transformed.x, transformed.y);
isFirst = false;
}
else
{
ctx.lineTo(transformed.x, transformed.y);
}
}
}
ctx.fill();
};