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vector: Better line joints

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Bug: #842
This commit is contained in:
Hajime Hoshi 2019-04-14 15:48:17 +09:00
parent 66cfe104ab
commit edbb5b4e0d
2 changed files with 51 additions and 55 deletions
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33
examples/vector/main.go
View File

@ -29,25 +29,20 @@ const (
screenHeight = 480
)
func update(screen *ebiten.Image) error {
if ebiten.IsDrawingSkipped() {
return nil
}
func drawEbitenText(screen *ebiten.Image) {
var path vector.Path
// E
path.MoveTo(20, 20)
path.MoveTo(60, 20)
path.LineTo(20, 20)
path.LineTo(20, 60)
path.MoveTo(20, 20)
path.LineTo(60, 20)
path.LineTo(60, 60)
path.MoveTo(20, 40)
path.LineTo(60, 40)
path.MoveTo(20, 60)
path.LineTo(60, 60)
// B
path.MoveTo(80, 20)
path.MoveTo(110, 20)
path.LineTo(80, 20)
path.LineTo(80, 60)
path.LineTo(110, 60)
path.LineTo(120, 50)
@ -69,14 +64,12 @@ func update(screen *ebiten.Image) error {
path.LineTo(180, 60)
// E
path.MoveTo(220, 20)
path.MoveTo(260, 20)
path.LineTo(220, 20)
path.LineTo(220, 60)
path.MoveTo(220, 20)
path.LineTo(260, 20)
path.LineTo(260, 60)
path.MoveTo(220, 40)
path.LineTo(260, 40)
path.MoveTo(220, 60)
path.LineTo(260, 60)
// N
path.MoveTo(280, 60)
@ -85,10 +78,16 @@ func update(screen *ebiten.Image) error {
path.LineTo(320, 20)
op := &vector.DrawPathOptions{}
op.LineWidth = 4
op.LineWidth = 8
op.StrokeColor = color.RGBA{0xdb, 0x56, 0x20, 0xff}
path.Draw(screen, op)
}
func update(screen *ebiten.Image) error {
if ebiten.IsDrawingSkipped() {
return nil
}
drawEbitenText(screen)
return nil
}

73
vector/path.go
View File

@ -19,9 +19,9 @@ package vector
import (
"image/color"
"math"
"github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/ebiten/vector/internal/math"
)
var emptyImage *ebiten.Image
@ -36,44 +36,30 @@ func init() {
emptyImage.ReplacePixels(pix)
}
type point struct {
x float32
y float32
}
type segment struct {
p0 point
p1 point
}
func (s *segment) atan2() float64 {
return math.Atan2(float64(s.p1.y-s.p0.y), float64(s.p1.x-s.p0.x))
}
// Path represents a collection of paths.
type Path struct {
segs [][]segment
cur point
segs [][]math.Segment
cur math.Point
}
// MoveTo skips the current position of the path to the given position (x, y) without adding any strokes.
func (p *Path) MoveTo(x, y float32) {
p.cur = point{x, y}
p.cur = math.Point{x, y}
if len(p.segs) > 0 && len(p.segs[len(p.segs)-1]) == 0 {
return
}
p.segs = append(p.segs, []segment{})
p.segs = append(p.segs, []math.Segment{})
}
// LineTo adds a segment to the path, which starts from the current position and ends to the given position (x, y).
// LineTo adds a math.Segment to the path, which starts from the current position and ends to the given position (x, y).
//
// LineTo updates the current position to (x, y).
func (p *Path) LineTo(x, y float32) {
if len(p.segs) == 0 {
p.segs = append(p.segs, []segment{})
p.segs = append(p.segs, []math.Segment{})
}
p.segs[len(p.segs)-1] = append(p.segs[len(p.segs)-1], segment{p.cur, point{x, y}})
p.cur = point{x, y}
p.segs[len(p.segs)-1] = append(p.segs[len(p.segs)-1], math.Segment{p.cur, math.Point{x, y}})
p.cur = math.Point{x, y}
}
func (p *Path) strokeVertices(lineWidth float32, clr color.Color) (vertices []ebiten.Vertex, indices []uint16) {
@ -86,18 +72,29 @@ func (p *Path) strokeVertices(lineWidth float32, clr color.Color) (vertices []eb
rf, gf, bf, af := float32(r)/0xffff, float32(g)/0xffff, float32(b)/0xffff, float32(a)/0xffff
idx := uint16(0)
for _, ss := range p.segs {
for _, s := range ss {
si, co := math.Sincos(s.atan2() + math.Pi/2)
dx, dy := float32(co)*lineWidth/2, float32(si)*lineWidth/2
v0 := point{s.p0.x + dx, s.p0.y + dy}
v1 := point{s.p0.x - dx, s.p0.y - dy}
v2 := point{s.p1.x + dx, s.p1.y + dy}
v3 := point{s.p1.x - dx, s.p1.y - dy}
for i, s := range ss {
s0 := s.Translate(-lineWidth / 2)
s1 := s.Translate(lineWidth / 2)
v0 := s0.P0
v1 := s1.P0
v2 := s0.P1
v3 := s1.P1
if i != 0 {
ps := ss[i-1]
v0 = ps.Translate(-lineWidth / 2).IntersectionAsLines(s0)
v1 = ps.Translate(lineWidth / 2).IntersectionAsLines(s1)
}
if i != len(ss)-1 {
ns := ss[i+1]
v2 = ns.Translate(-lineWidth / 2).IntersectionAsLines(s0)
v3 = ns.Translate(lineWidth / 2).IntersectionAsLines(s1)
}
vertices = append(vertices,
ebiten.Vertex{
DstX: v0.x,
DstY: v0.y,
DstX: v0.X,
DstY: v0.Y,
SrcX: 0,
SrcY: 0,
ColorR: rf,
@ -106,8 +103,8 @@ func (p *Path) strokeVertices(lineWidth float32, clr color.Color) (vertices []eb
ColorA: af,
},
ebiten.Vertex{
DstX: v1.x,
DstY: v1.y,
DstX: v1.X,
DstY: v1.Y,
SrcX: float32(sw),
SrcY: 0,
ColorR: rf,
@ -116,8 +113,8 @@ func (p *Path) strokeVertices(lineWidth float32, clr color.Color) (vertices []eb
ColorA: af,
},
ebiten.Vertex{
DstX: v2.x,
DstY: v2.y,
DstX: v2.X,
DstY: v2.Y,
SrcX: 0,
SrcY: float32(sh),
ColorR: rf,
@ -126,8 +123,8 @@ func (p *Path) strokeVertices(lineWidth float32, clr color.Color) (vertices []eb
ColorA: af,
},
ebiten.Vertex{
DstX: v3.x,
DstY: v3.y,
DstX: v3.X,
DstY: v3.Y,
SrcX: float32(sw),
SrcY: float32(sh),
ColorR: rf,