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vector: lazy point calculation

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This is a preparation for #2884.

Updates #2884
This commit is contained in:
Hajime Hoshi 2024-08-10 03:06:31 +09:00
parent 361da49887
commit 38b8ba5677
1 changed files with 132 additions and 61 deletions
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191
vector/path.go
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@ -31,6 +31,23 @@ const (
CounterClockwise
)
type opType int
const (
opTypeMoveTo opType = iota
opTypeLineTo
opTypeQuadTo
opTypeCubicTo
opTypeClose
)
type op struct {
typ opType
p1 point
p2 point
p3 point
}
func abs(x float32) float32 {
if x < 0 {
return -x
@ -48,16 +65,6 @@ type subpath struct {
closed bool
}
func (s *subpath) currentPosition() (point, bool) {
if len(s.points) == 0 {
return point{}, false
}
if s.closed {
return point{}, false
}
return s.points[len(s.points)-1], true
}
func (s *subpath) pointCount() int {
return len(s.points)
}
@ -91,15 +98,51 @@ func (s *subpath) close() {
// Path represents a collection of path subpathments.
type Path struct {
ops []op
subpaths []*subpath
}
func (p *Path) ensureSubpaths() []*subpath {
// TODO: Probably it is better to avoid returning a slice since allocation is heavy.
// What about walkSubpaths(func(*subpath))?
if len(p.subpaths) > 0 || len(p.ops) == 0 {
return p.subpaths
}
var cur point
for _, op := range p.ops {
switch op.typ {
case opTypeMoveTo:
p.subpaths = append(p.subpaths, &subpath{
points: []point{op.p1},
})
cur = op.p1
case opTypeLineTo:
p.lineTo(op.p1)
cur = op.p1
case opTypeQuadTo:
p.quadTo(cur, op.p1, op.p2, 0)
cur = op.p2
case opTypeCubicTo:
p.cubicTo(cur, op.p1, op.p2, op.p3, 0)
cur = op.p3
case opTypeClose:
p.close()
cur = point{}
}
}
return p.subpaths
}
// MoveTo starts a new subpath with the given position (x, y) without adding a subpath,
func (p *Path) MoveTo(x, y float32) {
p.subpaths = append(p.subpaths, &subpath{
points: []point{
{x: x, y: y},
},
p.subpaths = p.subpaths[:0]
p.ops = append(p.ops, op{
typ: opTypeMoveTo,
p1: point{x: x, y: y},
})
}
@ -107,22 +150,54 @@ func (p *Path) MoveTo(x, y float32) {
// and ends to the given position (x, y).
// If p doesn't have any subpaths or the last subpath is closed, LineTo sets (x, y) as the start position of a new subpath.
func (p *Path) LineTo(x, y float32) {
if len(p.subpaths) == 0 || p.subpaths[len(p.subpaths)-1].closed {
p.subpaths = append(p.subpaths, &subpath{
points: []point{
{x: x, y: y},
},
p.subpaths = p.subpaths[:0]
p.ops = append(p.ops, op{
typ: opTypeLineTo,
p1: point{x: x, y: y},
})
return
}
p.subpaths[len(p.subpaths)-1].appendPoint(point{x: x, y: y})
}
// QuadTo adds a quadratic Bézier curve to the path.
// (x1, y1) is the control point, and (x2, y2) is the destination.
func (p *Path) QuadTo(x1, y1, x2, y2 float32) {
p.quadTo(point{x: x1, y: y1}, point{x: x2, y: y2}, 0)
p.subpaths = p.subpaths[:0]
p.ops = append(p.ops, op{
typ: opTypeQuadTo,
p1: point{x: x1, y: y1},
p2: point{x: x2, y: y2},
})
}
// CubicTo adds a cubic Bézier curve to the path.
// (x1, y1) and (x2, y2) are the control points, and (x3, y3) is the destination.
func (p *Path) CubicTo(x1, y1, x2, y2, x3, y3 float32) {
p.subpaths = p.subpaths[:0]
p.ops = append(p.ops, op{
typ: opTypeCubicTo,
p1: point{x: x1, y: y1},
p2: point{x: x2, y: y2},
p3: point{x: x3, y: y3},
})
}
// Close adds a new line from the last position of the current subpath to the first position of the current subpath,
// and marks the current subpath closed.
// Following operations for this path will start with a new subpath.
func (p *Path) Close() {
p.subpaths = p.subpaths[:0]
p.ops = append(p.ops, op{
typ: opTypeClose,
})
}
func (p *Path) lineTo(pt point) {
if len(p.subpaths) == 0 || p.subpaths[len(p.subpaths)-1].closed {
p.subpaths = append(p.subpaths, &subpath{
points: []point{pt},
})
return
}
p.subpaths[len(p.subpaths)-1].appendPoint(pt)
}
// lineForTwoPoints returns parameters for a line passing through p0 and p1.
@ -154,24 +229,13 @@ func crossingPointForTwoLines(p00, p01, p10, p11 point) point {
}
}
func (p *Path) currentPosition() (point, bool) {
if len(p.subpaths) == 0 {
return point{}, false
}
return p.subpaths[len(p.subpaths)-1].currentPosition()
}
func (p *Path) quadTo(p1, p2 point, level int) {
func (p *Path) quadTo(p0, p1, p2 point, level int) {
if level > 10 {
return
}
p0, ok := p.currentPosition()
if !ok {
p0 = p1
}
if isPointCloseToSegment(p1, p0, p2, 0.5) {
p.LineTo(p2.x, p2.y)
p.lineTo(p2)
return
}
@ -187,27 +251,17 @@ func (p *Path) quadTo(p1, p2 point, level int) {
x: (p01.x + p12.x) / 2,
y: (p01.y + p12.y) / 2,
}
p.quadTo(p01, p012, level+1)
p.quadTo(p12, p2, level+1)
p.quadTo(p0, p01, p012, level+1)
p.quadTo(p012, p12, p2, level+1)
}
// CubicTo adds a cubic Bézier curve to the path.
// (x1, y1) and (x2, y2) are the control points, and (x3, y3) is the destination.
func (p *Path) CubicTo(x1, y1, x2, y2, x3, y3 float32) {
p.cubicTo(point{x: x1, y: y1}, point{x: x2, y: y2}, point{x: x3, y: y3}, 0)
}
func (p *Path) cubicTo(p1, p2, p3 point, level int) {
func (p *Path) cubicTo(p0, p1, p2, p3 point, level int) {
if level > 10 {
return
}
p0, ok := p.currentPosition()
if !ok {
p0 = p1
}
if isPointCloseToSegment(p1, p0, p3, 0.5) && isPointCloseToSegment(p2, p0, p3, 0.5) {
p.LineTo(p3.x, p3.y)
p.lineTo(p3)
return
}
@ -235,8 +289,8 @@ func (p *Path) cubicTo(p1, p2, p3 point, level int) {
x: (p012.x + p123.x) / 2,
y: (p012.y + p123.y) / 2,
}
p.cubicTo(p01, p012, p0123, level+1)
p.cubicTo(p123, p23, p3, level+1)
p.cubicTo(p0, p01, p012, p0123, level+1)
p.cubicTo(p0123, p123, p23, p3, level+1)
}
func normalize(p point) point {
@ -248,6 +302,26 @@ func cross(p0, p1 point) float32 {
return p0.x*p1.y - p1.x*p0.y
}
func (p *Path) currentPosition() (point, bool) {
if len(p.ops) == 0 {
return point{}, false
}
op := p.ops[len(p.ops)-1]
switch op.typ {
case opTypeMoveTo:
return op.p1, true
case opTypeLineTo:
return op.p1, true
case opTypeQuadTo:
return op.p2, true
case opTypeCubicTo:
return op.p3, true
case opTypeClose:
return point{}, false
}
return point{}, false
}
// ArcTo adds an arc curve to the path.
// (x1, y1) is the first control point, and (x2, y2) is the second control point.
func (p *Path) ArcTo(x1, y1, x2, y2, radius float32) {
@ -362,7 +436,7 @@ func (p *Path) Arc(x, y, radius, startAngle, endAngle float32, dir Direction) {
p.LineTo(x0, y0)
// Calculate the control points for an approximated Bézier curve.
// See https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/curves/beziers.
// See https://learn.microsoft.com/en-us/previous-versions/xamarin/xamarin-forms/user-interface/graphics/skiasharp/curves/beziers.
l := radius * float32(math.Tan(da/4)*4/3)
var cx0, cy0, cx1, cy1 float32
if dir == Clockwise {
@ -379,10 +453,7 @@ func (p *Path) Arc(x, y, radius, startAngle, endAngle float32, dir Direction) {
p.CubicTo(cx0, cy0, cx1, cy1, x1, y1)
}
// Close adds a new line from the last position of the current subpath to the first position of the current subpath,
// and marks the current subpath closed.
// Following operations for this path will start with a new subpath.
func (p *Path) Close() {
func (p *Path) close() {
if len(p.subpaths) == 0 {
return
}
@ -405,7 +476,7 @@ func (p *Path) AppendVerticesAndIndicesForFilling(vertices []ebiten.Vertex, indi
// TODO: Add tests.
base := uint16(len(vertices))
for _, subpath := range p.subpaths {
for _, subpath := range p.ensureSubpaths() {
if subpath.pointCount() < 3 {
continue
}
@ -486,7 +557,7 @@ func (p *Path) AppendVerticesAndIndicesForStroke(vertices []ebiten.Vertex, indic
return vertices, indices
}
for _, subpath := range p.subpaths {
for _, subpath := range p.ensureSubpaths() {
if subpath.pointCount() < 2 {
continue
}