added different line joint styles
This commit is contained in:
Thomas Friedel
parent
a8db8886c7
commit
f46b60da65
2 changed files with 78 additions and 35 deletions
18
canvas.go
18
canvas.go
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@ -42,6 +42,8 @@ type drawState struct {
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}
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font *Font
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fontSize float32
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lineJoin lineJoin
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lineEnd lineEnd
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/*
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The current transformation matrix.
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The current clipping region.
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@ -53,6 +55,17 @@ type drawState struct {
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*/
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}
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type lineJoin uint8
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type lineEnd uint8
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const (
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Miter = iota
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Bevel
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Round
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Square
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Butt
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)
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// New creates a new canvas with the given viewport coordinates.
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// While all functions on the canvas use the top left point as
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// the origin, since GL uses the bottom left coordinate, the
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@ -208,6 +221,11 @@ func (cv *Canvas) SetFont(font *Font, size float32) {
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cv.state.fontSize = size
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}
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// SetLineJoin sets the style of line joints for rendering a path with Stroke
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func (cv *Canvas) SetLineJoin(join lineJoin) {
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cv.state.lineJoin = join
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}
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// Save saves the current draw state to a stack
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func (cv *Canvas) Save() {
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cv.stateStack = append(cv.stateStack, cv.state)
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95
paths.go
95
paths.go
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@ -30,7 +30,6 @@ func (cv *Canvas) LineTo(x, y float32) {
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}
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func (cv *Canvas) Arc(x, y, radius, startAngle, endAngle float32, anticlockwise bool) {
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step := 6 / radius
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startAngle = fmath.Mod(startAngle, math.Pi*2)
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if startAngle < 0 {
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startAngle += math.Pi * 2
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@ -45,7 +44,7 @@ func (cv *Canvas) Arc(x, y, radius, startAngle, endAngle float32, anticlockwise
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startAngle += math.Pi * 2
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startAngle, endAngle = endAngle, startAngle
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}
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for a := startAngle; a < endAngle; a += step {
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for a := startAngle; a < endAngle; a += 0.1 {
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s, c := fmath.Sincos(a)
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cv.LineTo(x+radius*c, y+radius*s)
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}
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@ -112,40 +111,8 @@ func (cv *Canvas) Stroke() {
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l0x0f, l0y0f, l0x1f, l0y1f, l0x3f, l0y3f,
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l0x0f, l0y0f, l0x3f, l0y3f, l0x2f, l0y2f)
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// miter joints
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if p.attach {
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p2 := p.next
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v2 := p1.Sub(p2).Norm()
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v3 := lm.Vec2{v2[1], -v2[0]}.MulF(cv.state.stroke.lineWidth * 0.5)
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//v2 = v2.MulF(cv.state.stroke.lineWidth * 0.5)
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l1p0 := p2.Sub(v3)
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l1p1 := p1.Sub(v3)
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l1p2 := p2.Add(v3)
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l1p3 := p1.Add(v3)
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l1x1f, l1y1f := cv.vecToGL(l1p1)
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l1x3f, l1y3f := cv.vecToGL(l1p3)
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ip0 := lineIntersection(l0p0, l0p1, l1p1, l1p0)
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ip1 := lineIntersection(l0p2, l0p3, l1p3, l1p2)
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ix0f, iy0f := cv.vecToGL(ip0)
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ix1f, iy1f := cv.vecToGL(ip1)
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tris = append(tris,
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l0x1f, l0y1f, ix0f, iy0f, l1x1f, l1y1f,
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l0x1f, l0y1f, l1x1f, l1y1f, l1x3f, l1y3f,
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l0x1f, l0y1f, l1x3f, l1y3f, ix1f, iy1f,
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l0x1f, l0y1f, ix1f, iy1f, l0x3f, l0y3f)
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// todo this is an ugly hack...
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tris = append(tris,
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l0x1f, l0y1f, ix0f, iy0f, l1x1f, l1y1f,
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l0x1f, l0y1f, l1x1f, l1y1f, l0x3f, l0y3f,
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l0x1f, l0y1f, l0x3f, l0y3f, ix1f, iy1f,
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l0x1f, l0y1f, ix1f, iy1f, l1x3f, l1y3f)
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tris = cv.lineJoint(p, p0, p1, p.next, l0p0, l0p1, l0p2, l0p3, tris)
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}
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p0 = p1
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@ -169,6 +136,64 @@ func (cv *Canvas) Stroke() {
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gli.StencilFunc(gl_EQUAL, 0, 0xFF)
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}
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func (cv *Canvas) lineJoint(p pathPoint, p0, p1, p2, l0p0, l0p1, l0p2, l0p3 lm.Vec2, tris []float32) []float32 {
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v2 := p1.Sub(p2).Norm()
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v3 := lm.Vec2{v2[1], -v2[0]}.MulF(cv.state.stroke.lineWidth * 0.5)
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l0x1f, l0y1f := cv.vecToGL(l0p1)
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l0x3f, l0y3f := cv.vecToGL(l0p3)
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switch cv.state.lineJoin {
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case Miter:
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l1p0 := p2.Sub(v3)
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l1p1 := p1.Sub(v3)
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l1p2 := p2.Add(v3)
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l1p3 := p1.Add(v3)
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l1x1f, l1y1f := cv.vecToGL(l1p1)
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l1x3f, l1y3f := cv.vecToGL(l1p3)
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ip0 := lineIntersection(l0p0, l0p1, l1p1, l1p0)
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ip1 := lineIntersection(l0p2, l0p3, l1p3, l1p2)
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cxf, cyf := cv.vecToGL(p1)
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ix0f, iy0f := cv.vecToGL(ip0)
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ix1f, iy1f := cv.vecToGL(ip1)
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tris = append(tris,
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cxf, cyf, l0x1f, l0y1f, ix0f, iy0f,
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cxf, cyf, ix0f, iy0f, l1x1f, l1y1f,
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cxf, cyf, l1x3f, l1y3f, ix1f, iy1f,
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cxf, cyf, ix1f, iy1f, l0x3f, l0y3f)
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case Bevel:
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l1p1 := p1.Sub(v3)
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l1p3 := p1.Add(v3)
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l1x1f, l1y1f := cv.vecToGL(l1p1)
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l1x3f, l1y3f := cv.vecToGL(l1p3)
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cxf, cyf := cv.vecToGL(p1)
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tris = append(tris,
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cxf, cyf, l0x1f, l0y1f, l1x1f, l1y1f,
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cxf, cyf, l1x3f, l1y3f, l0x3f, l0y3f)
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case Round:
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cxf, cyf := cv.vecToGL(p1)
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radius := cv.state.stroke.lineWidth * 0.5
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step := 6 / radius
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p0x, p0y := cv.vecToGL(lm.Vec2{p1[0], p1[1] + radius})
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for angle := step; angle <= math.Pi*2+step; angle += 0.1 {
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s, c := fmath.Sincos(angle)
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p1x, p1y := cv.vecToGL(lm.Vec2{p1[0] + s*radius, p1[1] + c*radius})
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tris = append(tris, cxf, cyf, p0x, p0y, p1x, p1y)
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p0x, p0y = p1x, p1y
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}
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}
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return tris
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}
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func lineIntersection(a0, a1, b0, b1 lm.Vec2) lm.Vec2 {
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va := a1.Sub(a0)
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vb := b1.Sub(b0)
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