gl2d/math/miter.js

2D graphics package for WebGL

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
var vec2_1 = require("../struct/vec2");
/**
 * Measures the miter vector needed to join the two specified lines. Assumes the lines are measured from points listed in CCW order.
 * @param line1 The nonzero vector from the start of the first line to the end of the first line. Will not be modified.
 * @param line2 The nonzero vector from the start of the second line to the end of the second line. Will not be modified.
 * @param lineWidth The width of the second line (or half the width, if joining at the center of the lines).
 * @param miterLimit The maximum allowable miter length before a bevel is applied. Usually some multiple of lineWidth.
 */
function measureMiter(line1, line2, lineWidth, miterLimit) {
    // Measure the ortho norm of the previous vector and the next vector.
    var n1 = vec2_1.Vec2.create(line1);
    n1.normalize();
    n1.rotateRight();
    var n2 = vec2_1.Vec2.create(line2);
    n2.normalize();
    n2.rotateRight();
    // Average the ortho norms to get the miter vector.
    var miter = vec2_1.Vec2.create(n1);
    miter.add(n2);
    miter.normalize();
    // Measure the length of the miter by projecting it onto one of the ortho norms and inverting it.
    var length = lineWidth / miter.dot(n2);
    // Ensure length does not exceed miter limit
    if (length > miterLimit) {
        length = miterLimit;
    }
    // Scale vector to the measured length
    miter.mulScalar(length);
    return miter;
}
exports.measureMiter = measureMiter;
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