initial

CwJ/makie-demos/bezier.jl

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+using AbstractPlotting
+using AbstractPlotting.MakieLayout
+using GLMakie
+
+using LinearAlgebra
+
+
+function bezier()
+descr = """
+Bezier Curves: B(t) = ∑(binomial(n,i) * tⁱ * (1-t)⁽ⁿ⁻¹⁾ * Pᵢ)
+"""
+
+## From http://juliaplots.org/MakieReferenceImages/gallery//edit_polygon/index.html:
+function add_move!(scene, points, pplot)
+    idx = Ref(0); dragstart = Ref(false); startpos = Base.RefValue(Point2f0(0))
+    on(events(scene).mousedrag) do drag
+        if ispressed(scene, Mouse.left)
+            if drag == Mouse.down
+                plot, _idx = mouse_selection(scene)
+                if plot == pplot
+                    idx[] = _idx; dragstart[] = true
+                    startpos[] = to_world(scene, Point2f0(scene.events.mouseposition[]))
+                end
+            elseif drag == Mouse.pressed && dragstart[] && checkbounds(Bool, points[], idx[])
+                pos = to_world(scene, Point2f0(scene.events.mouseposition[]))
+
+                # very wierd, but we work with components
+                # not vector
+                z = zero(eltype(pos))
+                x,y = pos
+
+                ptidx = idx[]
+
+                x = clamp(x, -1, 1)
+                y = clamp(y, -1, 1)
+                
+                points[][idx[]] = [x,y]
+                points[] = points[]
+            end
+        else
+            dragstart[] = false
+        end
+        return
+    end
+end
+
+upperpoints = Point2f0[(0,0), (5, 0), (5, 5), (0,5)]
+lowerpoints = (Point2f0[(0,0), (5, 0), (5, -5), (0,-5)])
+
+points = Node(Point2f0[(1, 4), (3, 0), (4,-4.0)])
+
+# where we lay our scene:
+scene, layout = layoutscene()
+layout.halign = :left
+layout.valign = :top
+
+
+p = layout[1, 1:2] = LScene(scene)
+rowsize!(layout, 1, Auto(1))
+colsize!(layout, 1, Auto(1))
+colsize!(layout, 2, Auto(1))
+
+npts = layout[2,1:2] = LSlider(scene, range=3:12, startvalue=4)
+layout[3,1:2] = LText(scene, chomp(descr))
+
+# points = Node(Point2f0[(-1/2, -1/2),
+#                        (-1/2, 1/2),
+#                        (1/2, 1/2),
+#                        (1/2, -1/2)])
+
+#npts = 6
+#ts = range(3pi/2, -pi/2, length=npts+2)
+#points = Node(Point2f0[(cos(t),sin(t)) for t in ts[2:end-1]])
+
+points = lift(npts.value) do val
+    ts = range(3pi/2, -pi/2, length=val+2)
+    Point2f0[(cos(t),sin(t)) for t in ts[2:end-1]]
+end
+    
+
+
+
+
+
+bcurve = lift(points) do pts
+    n = length(pts) - 1
+    B = t -> begin
+        tot = 0.0
+        for (i′, Pᵢ) in enumerate(pts)
+            i = i′ - 1
+            tot += binomial(n, i) * t^i * (1-t)^(n-i) * Pᵢ
+        end
+        tot
+    end
+    ts = range(0, 1, length=200)
+    Point2f0[B(t) for t in ts]
+end
+
+
+
+lines!(p.scene, bcurve, strokecolor=:black, strokewidth=15)
+lines!(p.scene, points, strokecolor=:gray90, strokewidth=5, linestyle=:dash)
+scatter!(p.scene, points)
+xlims!(p.scene, (-1,1))
+ylims!(p.scene, (-1,1))
+add_move!(p.scene, points, p.scene[end])
+
+
+
+scene
+
+end