The avatar for @robinhouston
Robin Houston
Public
Edited
Apr 24, 2022
Fork of Building a circle
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WIDTH = Math.min(600, width)
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HEIGHT = WIDTH
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A = [50, HEIGHT/2]
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α = 1
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X = 100
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θ = t * Math.PI/2
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g = Math.tan(θ)
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{
const ct = canvas.ct;
const { sin, cos } = Math;

ct.clearRect(0, 0, WIDTH, HEIGHT);

// Draw the X indicator
ct.beginPath();
ct.moveTo(X, 0);
ct.lineTo(X, HEIGHT);
ct.lineWidth = 1;
ct.strokeStyle = "#ccc";
ct.stroke();

// Draw the two lines
ct.beginPath();
ct.moveTo(A[0], A[1]);
ct.lineTo(WIDTH, A[1] + g * (WIDTH - A[0]));

ct.moveTo(A[0], A[1]);
ct.lineTo(WIDTH, A[1] + (g + α) * (WIDTH - A[0]));

ct.lineWidth = 1;
ct.strokeStyle = "blue";
ct.stroke();

// Draw the constant-height line segment
ct.beginPath();
ct.moveTo(X, A[1] + g * (X - A[0]));
ct.lineTo(X, A[1] + (g + α) * (X - A[0]));

ct.lineWidth = 2;
ct.strokeStyle = "red";
ct.stroke();

return this || html`(<i>the drawing function</i>)`;
}
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