build/postprocessing.esm.js
function calculateDiagonalAreaForPixel(p1, p2, pX, pY) {

	let a;
	let x, y;
	let offsetX, offsetY;

	for(a = 0, y = 0; y < DIAGONAL_SAMPLES; ++y) {

		for(x = 0; x < DIAGONAL_SAMPLES; ++x) {

			offsetX = x / (DIAGONAL_SAMPLES - 1.0);
			offsetY = y / (DIAGONAL_SAMPLES - 1.0);

			if(isInsideArea(p1, p2, pX + offsetX, pY + offsetY)) {

				++a;

			}

		}

	}

	return a / (DIAGONAL_SAMPLES * DIAGONAL_SAMPLES);

}
function calculateDiagonalAreaForPixel(p1, p2, pX, pY) {

	let a;
	let x, y;
	let offsetX, offsetY;

	for(a = 0, y = 0; y < DIAGONAL_SAMPLES; ++y) {

		for(x = 0; x < DIAGONAL_SAMPLES; ++x) {

			offsetX = x / (DIAGONAL_SAMPLES - 1.0);
			offsetY = y / (DIAGONAL_SAMPLES - 1.0);

			if(isInsideArea(p1, p2, pX + offsetX, pY + offsetY)) {

				++a;

			}

		}

	}

	return a / (DIAGONAL_SAMPLES * DIAGONAL_SAMPLES);

}
Calculates the area under the line p1 -> p2 for the pixel p using brute force
sampling.

@private
@param {Vector2} p1 - The lower bounds of the area.
@param {Vector2} p2 - The upper bounds of the area.
@param {Number} pX - The X-coordinates.
@param {Number} pY - The Y-coordinates.
@return {Number} The amount of pixels inside the area relative to the total amount of sampled pixels.