openpencil/src/engine/vector.ts
Danila Poyarkov f741eaa296 Fix open paths rendering as closed
Only close a loop path when the last segment ends at the first
segment's start vertex.
2026-02-28 07:15:07 +03:00

309 lines
8.9 KiB
TypeScript

import type { CanvasKit, Path } from 'canvaskit-wasm'
import type { HandleMirroring, VectorNetwork, VectorRegion, VectorSegment, VectorVertex, WindingRule } from './scene-graph'
// --- vectorNetworkBlob binary format ---
// Header: [numVertices:u32, numSegments:u32, numRegions:u32] (12 bytes)
// Vertex: [styleOverrideIdx:u32, x:f32, y:f32] (12 bytes)
// Segment: [styleOverrideIdx:u32, start:u32, tsX:f32, tsY:f32, end:u32, teX:f32, teY:f32] (28 bytes)
// Region: [windingRule:u32, numLoops:u32, {numSegs:u32, segIdx...}... ] (variable)
interface StyleOverride {
styleID: number
handleMirroring?: string
}
export function decodeVectorNetworkBlob(
data: Uint8Array,
styleOverrideTable?: StyleOverride[]
): VectorNetwork {
const view = new DataView(data.buffer, data.byteOffset, data.byteLength)
let o = 0
const nV = view.getUint32(o, true); o += 4
const nS = view.getUint32(o, true); o += 4
const nR = view.getUint32(o, true); o += 4
const styleMap = new Map<number, StyleOverride>()
if (styleOverrideTable) {
for (const entry of styleOverrideTable) {
styleMap.set(entry.styleID, entry)
}
}
const vertices: VectorVertex[] = []
for (let i = 0; i < nV; i++) {
const styleIdx = view.getUint32(o, true); o += 4
const x = view.getFloat32(o, true); o += 4
const y = view.getFloat32(o, true); o += 4
const override = styleMap.get(styleIdx)
vertices.push({
x,
y,
handleMirroring: (override?.handleMirroring as HandleMirroring) ?? 'NONE'
})
}
const segments: VectorSegment[] = []
for (let i = 0; i < nS; i++) {
o += 4 // styleOverrideIdx (unused for segments currently)
const start = view.getUint32(o, true); o += 4
const tsX = view.getFloat32(o, true); o += 4
const tsY = view.getFloat32(o, true); o += 4
const end = view.getUint32(o, true); o += 4
const teX = view.getFloat32(o, true); o += 4
const teY = view.getFloat32(o, true); o += 4
segments.push({
start,
end,
tangentStart: { x: tsX, y: tsY },
tangentEnd: { x: teX, y: teY }
})
}
const regions: VectorRegion[] = []
for (let i = 0; i < nR; i++) {
const windingRuleU32 = view.getUint32(o, true); o += 4
const windingRule: WindingRule = windingRuleU32 === 0 ? 'EVENODD' : 'NONZERO'
const numLoops = view.getUint32(o, true); o += 4
const loops: number[][] = []
for (let j = 0; j < numLoops; j++) {
const numSegs = view.getUint32(o, true); o += 4
const loop: number[] = []
for (let k = 0; k < numSegs; k++) {
loop.push(view.getUint32(o, true)); o += 4
}
loops.push(loop)
}
regions.push({ windingRule, loops })
}
return { vertices, segments, regions }
}
export function encodeVectorNetworkBlob(network: VectorNetwork): Uint8Array {
const { vertices, segments, regions } = network
let regionBytes = 0
for (const region of regions) {
regionBytes += 8 // windingRule + numLoops
for (const loop of region.loops) {
regionBytes += 4 + loop.length * 4 // numSegs + indices
}
}
const totalBytes = 12 + vertices.length * 12 + segments.length * 28 + regionBytes
const buf = new ArrayBuffer(totalBytes)
const view = new DataView(buf)
let o = 0
view.setUint32(o, vertices.length, true); o += 4
view.setUint32(o, segments.length, true); o += 4
view.setUint32(o, regions.length, true); o += 4
for (const v of vertices) {
view.setUint32(o, 0, true); o += 4 // styleOverrideIdx (TODO: encode handleMirroring)
view.setFloat32(o, v.x, true); o += 4
view.setFloat32(o, v.y, true); o += 4
}
for (const seg of segments) {
view.setUint32(o, 0, true); o += 4 // styleOverrideIdx
view.setUint32(o, seg.start, true); o += 4
view.setFloat32(o, seg.tangentStart.x, true); o += 4
view.setFloat32(o, seg.tangentStart.y, true); o += 4
view.setUint32(o, seg.end, true); o += 4
view.setFloat32(o, seg.tangentEnd.x, true); o += 4
view.setFloat32(o, seg.tangentEnd.y, true); o += 4
}
for (const region of regions) {
view.setUint32(o, region.windingRule === 'EVENODD' ? 0 : 1, true); o += 4
view.setUint32(o, region.loops.length, true); o += 4
for (const loop of region.loops) {
view.setUint32(o, loop.length, true); o += 4
for (const segIdx of loop) {
view.setUint32(o, segIdx, true); o += 4
}
}
}
return new Uint8Array(buf)
}
export function vectorNetworkToPath(ck: CanvasKit, network: VectorNetwork): Path {
const path = new ck.Path()
const { vertices, segments, regions } = network
if (regions.length > 0) {
for (const region of regions) {
for (const loop of region.loops) {
addLoopToPath(path, loop, segments, vertices)
}
path.setFillType(
region.windingRule === 'EVENODD' ? ck.FillType.EvenOdd : ck.FillType.Winding
)
}
} else {
// No regions — draw all segments as open paths
const visited = new Set<number>()
const chains = buildChains(segments, vertices.length)
for (const chain of chains) {
if (chain.length === 0) continue
const firstSeg = segments[chain[0]]
path.moveTo(vertices[firstSeg.start].x, vertices[firstSeg.start].y)
for (const segIdx of chain) {
visited.add(segIdx)
addSegmentToPath(path, segments[segIdx], vertices)
}
}
// Any remaining disconnected segments
for (let i = 0; i < segments.length; i++) {
if (visited.has(i)) continue
const seg = segments[i]
path.moveTo(vertices[seg.start].x, vertices[seg.start].y)
addSegmentToPath(path, seg, vertices)
}
}
return path
}
function addLoopToPath(
path: Path,
loop: number[],
segments: VectorSegment[],
vertices: VectorVertex[]
): void {
if (loop.length === 0) return
const firstSeg = segments[loop[0]]
path.moveTo(vertices[firstSeg.start].x, vertices[firstSeg.start].y)
for (const segIdx of loop) {
addSegmentToPath(path, segments[segIdx], vertices)
}
const lastSeg = segments[loop[loop.length - 1]]
if (lastSeg.end === firstSeg.start) {
path.close()
}
}
function addSegmentToPath(
path: Path,
seg: VectorSegment,
vertices: VectorVertex[]
): void {
const start = vertices[seg.start]
const end = vertices[seg.end]
const ts = seg.tangentStart
const te = seg.tangentEnd
const isLine = ts.x === 0 && ts.y === 0 && te.x === 0 && te.y === 0
if (isLine) {
path.lineTo(end.x, end.y)
} else {
// Cubic bezier: control points are tangent offsets from start/end
path.cubicTo(
start.x + ts.x,
start.y + ts.y,
end.x + te.x,
end.y + te.y,
end.x,
end.y
)
}
}
function buildChains(segments: VectorSegment[], _vertexCount: number): number[][] {
if (segments.length === 0) return []
// Build adjacency: for each vertex, which segments connect to it
const adj = new Map<number, number[]>()
for (let i = 0; i < segments.length; i++) {
const s = segments[i]
if (!adj.has(s.start)) adj.set(s.start, [])
if (!adj.has(s.end)) adj.set(s.end, [])
adj.get(s.start)!.push(i)
adj.get(s.end)!.push(i)
}
const visited = new Set<number>()
const chains: number[][] = []
// Start from degree-1 vertices (endpoints) or any unvisited
const degree1 = [...adj.entries()]
.filter(([, segs]) => segs.length === 1)
.map(([v]) => v)
const startVertices = degree1.length > 0
? degree1
: [segments[0].start]
for (const startVertex of startVertices) {
let current = startVertex
const chain: number[] = []
while (true) {
const segs = adj.get(current)
if (!segs) break
const nextSeg = segs.find((s) => !visited.has(s))
if (nextSeg === undefined) break
visited.add(nextSeg)
chain.push(nextSeg)
const seg = segments[nextSeg]
current = seg.start === current ? seg.end : seg.start
}
if (chain.length > 0) chains.push(chain)
}
return chains
}
export function computeVectorBounds(
network: VectorNetwork
): { x: number; y: number; width: number; height: number } {
if (network.vertices.length === 0) {
return { x: 0, y: 0, width: 0, height: 0 }
}
let minX = Infinity
let minY = Infinity
let maxX = -Infinity
let maxY = -Infinity
for (const v of network.vertices) {
minX = Math.min(minX, v.x)
minY = Math.min(minY, v.y)
maxX = Math.max(maxX, v.x)
maxY = Math.max(maxY, v.y)
}
// Also consider bezier control points for tighter bounds
for (const seg of network.segments) {
const start = network.vertices[seg.start]
const end = network.vertices[seg.end]
const cp1x = start.x + seg.tangentStart.x
const cp1y = start.y + seg.tangentStart.y
const cp2x = end.x + seg.tangentEnd.x
const cp2y = end.y + seg.tangentEnd.y
minX = Math.min(minX, cp1x, cp2x)
minY = Math.min(minY, cp1y, cp2y)
maxX = Math.max(maxX, cp1x, cp2x)
maxY = Math.max(maxY, cp1y, cp2y)
}
return { x: minX, y: minY, width: maxX - minX, height: maxY - minY }
}