mstar/canvas
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added line end styles

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This commit is contained in:
Thomas Friedel 2018-01-31 21:37:47 +01:00
parent f46b60da65
commit d9854d540e
2 changed files with 46 additions and 12 deletions
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5
canvas.go
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@ -226,6 +226,11 @@ func (cv *Canvas) SetLineJoin(join lineJoin) {
cv.state.lineJoin = join
}
// SetLineEnd sets the style of line endings for rendering a path with Stroke
func (cv *Canvas) SetLineEnd(end lineEnd) {
cv.state.lineEnd = end
}
// Save saves the current draw state to a stack
func (cv *Canvas) Save() {
cv.stateStack = append(cv.stateStack, cv.state)

53
paths.go
View file

@ -85,23 +85,49 @@ func (cv *Canvas) Stroke() {
tris := buf[:0]
tris = append(tris, -1, -1, -1, 1, 1, 1, -1, -1, 1, 1, 1, -1)
start := true
var p0 lm.Vec2
for _, p := range cv.path {
if p.move {
p0 = p.pos
start = true
continue
}
p1 := p.pos
v0 := p1.Sub(p0).Norm()
v1 := lm.Vec2{v0[1], -v0[0]}.MulF(cv.state.stroke.lineWidth * 0.5)
//v0 = v0.MulF(cv.state.stroke.lineWidth * 0.5)
v0 = v0.MulF(cv.state.stroke.lineWidth * 0.5)
l0p0 := p0.Add(v1)
l0p1 := p1.Add(v1)
l0p2 := p0.Sub(v1)
l0p3 := p1.Sub(v1)
if start {
switch cv.state.lineEnd {
case Butt:
// no need to do anything
case Square:
l0p0 = l0p0.Sub(v0)
l0p2 = l0p2.Sub(v0)
case Round:
tris = cv.addCircleTris(p0, cv.state.stroke.lineWidth*0.5, tris)
}
}
if !p.attach {
switch cv.state.lineEnd {
case Butt:
// no need to do anything
case Square:
l0p1 = l0p1.Add(v0)
l0p3 = l0p3.Add(v0)
case Round:
tris = cv.addCircleTris(p1, cv.state.stroke.lineWidth*0.5, tris)
}
}
l0x0f, l0y0f := cv.vecToGL(l0p0)
l0x1f, l0y1f := cv.vecToGL(l0p1)
l0x2f, l0y2f := cv.vecToGL(l0p2)
@ -116,6 +142,7 @@ func (cv *Canvas) Stroke() {
}
p0 = p1
start = false
}
gli.BufferData(gl_ARRAY_BUFFER, len(tris)*4, unsafe.Pointer(&tris[0]), gl_STREAM_DRAW)
@ -178,22 +205,24 @@ func (cv *Canvas) lineJoint(p pathPoint, p0, p1, p2, l0p0, l0p1, l0p2, l0p3 lm.V
cxf, cyf, l0x1f, l0y1f, l1x1f, l1y1f,
cxf, cyf, l1x3f, l1y3f, l0x3f, l0y3f)
case Round:
cxf, cyf := cv.vecToGL(p1)
radius := cv.state.stroke.lineWidth * 0.5
step := 6 / radius
p0x, p0y := cv.vecToGL(lm.Vec2{p1[0], p1[1] + radius})
for angle := step; angle <= math.Pi*2+step; angle += 0.1 {
s, c := fmath.Sincos(angle)
p1x, p1y := cv.vecToGL(lm.Vec2{p1[0] + s*radius, p1[1] + c*radius})
tris = append(tris, cxf, cyf, p0x, p0y, p1x, p1y)
p0x, p0y = p1x, p1y
}
tris = cv.addCircleTris(p1, cv.state.stroke.lineWidth*0.5, tris)
}
return tris
}
func (cv *Canvas) addCircleTris(p lm.Vec2, radius float32, tris []float32) []float32 {
cxf, cyf := cv.vecToGL(p)
p0x, p0y := cv.vecToGL(lm.Vec2{p[0], p[1] + radius})
for angle := float32(0.1); angle <= math.Pi*2+0.1; angle += 0.1 {
s, c := fmath.Sincos(angle)
p1x, p1y := cv.vecToGL(lm.Vec2{p[0] + s*radius, p[1] + c*radius})
tris = append(tris, cxf, cyf, p0x, p0y, p1x, p1y)
p0x, p0y = p1x, p1y
}
return tris
}
func lineIntersection(a0, a1, b0, b1 lm.Vec2) lm.Vec2 {
va := a1.Sub(a0)
vb := b1.Sub(b0)