120 lines
2.8 KiB
Go
120 lines
2.8 KiB
Go
package canvas
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import (
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"unsafe"
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"github.com/tfriedel6/lm"
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)
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func (cv *Canvas) BeginPath() {
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if cv.path == nil {
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cv.path = make([]pathPoint, 0, 100)
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}
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cv.path = cv.path[:0]
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}
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func (cv *Canvas) MoveTo(x, y float32) {
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cv.path = append(cv.path, pathPoint{pos: lm.Vec2{x, y}, move: true})
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}
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func (cv *Canvas) LineTo(x, y float32) {
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cv.path = append(cv.path, pathPoint{pos: lm.Vec2{x, y}, move: false})
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}
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func (cv *Canvas) ClosePath() {
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if len(cv.path) == 0 {
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return
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}
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cv.path = append(cv.path, pathPoint{pos: cv.path[0].pos, move: false})
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}
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func (cv *Canvas) Stroke() {
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if len(cv.path) == 0 {
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return
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}
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cv.activate()
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gli.Enable(gl_STENCIL_TEST)
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gli.ColorMask(false, false, false, false)
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gli.StencilFunc(gl_ALWAYS, 1, 0xFF)
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gli.StencilOp(gl_KEEP, gl_KEEP, gl_REPLACE)
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gli.StencilMask(0xFF)
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gli.Clear(gl_STENCIL_BUFFER_BIT)
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gli.UseProgram(sr.id)
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gli.Uniform4f(sr.color, cv.stroke.r, cv.stroke.g, cv.stroke.b, cv.stroke.a)
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gli.EnableVertexAttribArray(sr.vertex)
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gli.BindBuffer(gl_ARRAY_BUFFER, buf)
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var buf [1000]float32
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tris := buf[:0]
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tris = append(tris, -1, -1, -1, 1, 1, 1, -1, -1, 1, 1, 1, -1)
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p0 := cv.path[0].pos
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for _, p := range cv.path {
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if p.move {
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p0 = p.pos
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continue
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}
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p1 := p.pos
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v1 := p1.Sub(p0).Norm()
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v2 := lm.Vec2{v1[1], -v1[0]}.MulF(cv.stroke.lineWidth * 0.5)
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v1 = v1.MulF(cv.stroke.lineWidth * 0.5)
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x0f, y0f := cv.vecToGL(p0.Sub(v1).Add(v2))
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x1f, y1f := cv.vecToGL(p1.Add(v1).Add(v2))
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x2f, y2f := cv.vecToGL(p1.Add(v1).Sub(v2))
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x3f, y3f := cv.vecToGL(p0.Sub(v1).Sub(v2))
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tris = append(tris, x0f, y0f, x1f, y1f, x2f, y2f, x0f, y0f, x2f, y2f, x3f, y3f)
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p0 = p1
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}
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gli.BufferData(gl_ARRAY_BUFFER, len(tris)*4, unsafe.Pointer(&tris[0]), gl_STREAM_DRAW)
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gli.VertexAttribPointer(sr.vertex, 2, gl_FLOAT, false, 0, nil)
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gli.DrawArrays(gl_TRIANGLES, 6, int32(len(tris)/2-6))
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gli.ColorMask(true, true, true, true)
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gli.StencilFunc(gl_EQUAL, 1, 0xFF)
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gli.StencilMask(0)
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gli.DrawArrays(gl_TRIANGLE_FAN, 0, 6)
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gli.DisableVertexAttribArray(sr.vertex)
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gli.Disable(gl_STENCIL_TEST)
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}
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func (cv *Canvas) Fill() {
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if len(cv.path) < 3 {
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return
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}
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cv.activate()
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gli.UseProgram(sr.id)
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gli.Uniform4f(sr.color, cv.fill.r, cv.fill.g, cv.fill.b, cv.fill.a)
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gli.EnableVertexAttribArray(sr.vertex)
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gli.BindBuffer(gl_ARRAY_BUFFER, buf)
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var buf [1000]float32
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tris := buf[:0]
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tris = append(tris, -1, -1, -1, 1, 1, 1, -1, -1, 1, 1, 1, -1)
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tris = triangulatePath(cv.path, tris)
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total := len(tris)
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for i := 12; i < total; i += 2 {
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x, y := tris[i], tris[i+1]
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tris[i], tris[i+1] = cv.ptToGL(x, y)
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}
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gli.BufferData(gl_ARRAY_BUFFER, len(tris)*4, unsafe.Pointer(&tris[0]), gl_STREAM_DRAW)
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gli.VertexAttribPointer(sr.vertex, 2, gl_FLOAT, false, 0, nil)
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gli.DrawArrays(gl_TRIANGLES, 6, int32(len(tris)/2-6))
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gli.DisableVertexAttribArray(sr.vertex)
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}
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