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Further improve normal corrector in spiro expansion

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This commit is contained in:
be5invis 2021-04-18 19:46:05 -07:00
parent bb863cd4ff
commit 040b5fd487
7 changed files with 58 additions and 43 deletions
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5
font-src/support/parameters.js
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@ -87,8 +87,11 @@ function getBlendArg(blendArgs, style) {
function hiveBlend(hive, value) {
if (!hive || !hive.blend || value == null) return hive;
const generatedHive = {};
const block = hive.blend;
delete hive.blend;
const generatedHive = { ...hive };
let keys = new Set();
for (const grade in block) {
if (!isFinite(parseFloat(grade))) continue;

60
font-src/support/spiro-expand.js
View file

@ -1,6 +1,17 @@
const Transform = require("./transform");
const { linreg } = require("./utils");
class BiKnot {
constructor(type, x, y, d1, d2) {
this.type = type;
this.x = x;
this.y = y;
this.d1 = d1;
this.d2 = d2;
this.origTangent = null;
this.proposedNormal = null;
}
}
class SpiroExpansionContext1 {
constructor(gizmo) {
this.gizmo = gizmo;
@ -13,30 +24,22 @@ class SpiroExpansionContext1 {
moveTo(x, y, unimportant) {
if (unimportant) return;
if (!isFinite(x) || !isFinite(y)) throw new Error("NaN detected.");
this.controlKnots.push({
type: "g4",
d1: this.defaultD1,
d2: this.defaultD2,
...this.gizmo.apply({ x, y })
});
const tfZ = this.gizmo.apply({ x, y });
this.controlKnots.push(new BiKnot("g2", tfZ.x, tfZ.y, this.defaultD1, this.defaultD2));
}
arcTo(arc, x, y) {
if (!isFinite(x) || !isFinite(y)) throw new Error("NaN detected.");
const k0 = this.controlKnots[this.controlKnots.length - 1];
if (!k0) throw new Error("Unreachable: lineTo called before moveTo");
if (k0.normalAngle == null) {
const tfDerive0 = this.gizmo.applyOffset({ x: arc.deriveX0, y: arc.deriveY0 });
k0.normalAngle = Math.PI / 2 + Math.atan2(tfDerive0.y, tfDerive0.x);
if (k0.origTangent == null) {
k0.origTangent = this.gizmo.applyOffset({ x: arc.deriveX0, y: arc.deriveY0 });
}
{
const tfDerive1 = this.gizmo.applyOffset({ x: arc.deriveX1, y: arc.deriveY1 });
this.controlKnots.push({
type: "g4",
d1: k0.d1,
d2: k0.d2,
...this.gizmo.apply({ x, y }),
normalAngle: Math.PI / 2 + Math.atan2(tfDerive1.y, tfDerive1.x)
});
const tfZ = this.gizmo.apply({ x, y });
const bz = new BiKnot("g2", tfZ.x, tfZ.y, k0.d1, k0.d2);
bz.origTangent = tfDerive1;
this.controlKnots.push(bz);
}
}
setWidth(l, r) {
@ -87,8 +90,8 @@ class SpiroExpansionContext1 {
dx = knot.proposedNormal.x;
dy = knot.proposedNormal.y;
} else {
dx = normalX(knot.normalAngle, contrast);
dy = normalY(knot.normalAngle, contrast);
dx = normalX(knot.origTangent, contrast);
dy = normalY(knot.origTangent, contrast);
}
lhs[j] = {
type: knot.type,
@ -155,24 +158,27 @@ class SpiroExpansionContext2 {
}
arcTo(arc, x, y) {
if (this.nKnotsProcessed === 1) {
const angle = computeNormalAngle(this.gizmo, arc.deriveX0, arc.deriveY0);
if (isFinite(angle)) this.controlKnots[0].normalAngle = angle;
const d = this.gizmo.applyOffset({ x: arc.deriveX0, y: arc.deriveY0 });
if (isTangentValid(d)) this.controlKnots[0].origTangent = d;
else throw new Error("NaN angle detected.");
}
{
const angle = computeNormalAngle(this.gizmo, arc.deriveX1, arc.deriveY1);
if (isFinite(angle)) this.controlKnots[this.nKnotsProcessed].normalAngle = angle;
const d = this.gizmo.applyOffset({ x: arc.deriveX1, y: arc.deriveY1 });
if (isTangentValid(d)) this.controlKnots[this.nKnotsProcessed].origTangent = d;
else throw new Error("NaN angle detected.");
}
this.nKnotsProcessed += 1;
}
}
function normalX(angle, contrast) {
return Math.cos(angle) * contrast;
function isTangentValid(d) {
return isFinite(d.x) && isFinite(d.y);
}
function normalY(angle) {
return Math.sin(angle);
function normalX(tangent, contrast) {
return contrast * (-tangent.y / Math.hypot(tangent.x, tangent.y));
}
function normalY(tangent) {
return tangent.x / Math.hypot(tangent.x, tangent.y);
}
function reverseKnotType(ty) {
return ty === "left" ? "right" : ty === "right" ? "left" : ty;