Define CrossSection; simplify plotting.jl accordingly

Author: wsshin

Diff for: src/planar/cross_section.jl

@@ -0,0 +1,47 @@
+export CrossSection
+
+mutable struct CrossSection{S<:Shape3} <: Shape2
+    shp::S  # 3D shape
+    p::S²Float{3,9}  # projection matrix to cross-sectional coordinates; must be orthonormal; 3rd entry of projection is along normal axis
+    c::Float  # intercept on axis normal to cross section
+end
+
+CrossSection(shp::S,
+             n::SReal{3},
+             c::Real
+             ) where {S<:Shape3} =
+    (n̂ = normalize(n); CrossSection{S}(shp, [orthoaxes(n̂)... n̂]', c))
+
+CrossSection(shp::Shape3, n::AbsVecReal, c::Real) = CrossSection(shp, SVec{3}(n), c)
+
+function (shp::Shape3)(ax::Symbol, c::Real)
+    ax==:x || ax==:y || ax==:z || @error "ax = $(ax) should be :x or :y or :z."
+
+    ind_n̂ = (ax==:x) + 2(ax==:y) + 3(ax==:z)  # ind_n̂ = 1, 2, 3 for ax = :x, :y, :z
+    n̂ = SVec(ntuple(identity,Val(3))) .== ind_n̂
+
+    return CrossSection(shp, n̂, c)
+end
+
+coord3d(x::SReal{2}, s::CrossSection) = (y = SFloat{3}(x.data..., s.c); s.p' * y)
+
+level(x::SReal{2}, s::CrossSection) = level(coord3d(x,s), s.shp)
+
+function surfpt_nearby(x::SReal{2}, s::CrossSection)
+    pt, nout = surfpt_nearby(coord3d(x,s), s.shp)
+
+    uv = SVec(1,2)
+    pt2 = (s.p * pt)[uv]
+    nout2 = normalize((s.p * nout)[uv])
+
+    return pt2, nout2
+end
+
+translate(s::CrossSection, ∆::SReal{2}) = CrossSection(translate(s.shp, coord3d(∆)), s.p, s.c)
+
+# This does not create the tightest bounds.  For the tightest bounds, this function should
+# be implemented for CrossSection{S} for each S<:Shape3.
+function bounds(s::CrossSection)
+    bₙ, bₚ = bounds(s.shp)
+    return s.p * bₙ, s.p * bₚ
+end

Diff for: src/planar/planar.jl

@@ -1,3 +1,4 @@
+include("cross_section.jl")
 include("polygon.jl")
 include("special.jl")
 include("sector.jl")

Diff for: src/util/plotting.jl

@@ -30,29 +30,6 @@ function Makie.plot!(ds::DrawShape{<:Tuple{Shape2}})
     return ds
 end
 
-# Implement drawshape!() for 3D shapes.
-function Makie.plot!(ds::DrawShape{<:Tuple{Shape3,Tuple{Symbol,Real}}})
-    res₀ = ds.res.val  # fields found by examining typeof(ds) and fieldnames(typeof(ds)), etc
-    hres = ds.hres.val
-    vres = ds.vres.val
-
-    # If hres and vres are set to valid values, use them; otherwise use res₀.
-    hres≤1 && (hres = res₀)
-    vres≥1 && (vres = res₀)
-
-    hres>1 || @error "hres = $hres should at least 2."
-    vres>1 || @error "vres = $vres should at least 2."
-
-    shp = ds[1]
-    cs = ds[2]
-    res = (hres, vres)
-
-    # Makie.convert_arguments() defined below handles this new signature.
-    contour!(ds, shp, cs, res, levels=SVec(0.0); ds.attributes...)
-
-    return ds
-end
-
 # Define the new signature of contour!() used in drawshape!() for 2D shapes.
 function Makie.convert_arguments(P::SurfaceLike, shp::Shape2, res::Tuple2{Integer})
     lower, upper = bounds(shp)
@@ -66,30 +43,3 @@ function Makie.convert_arguments(P::SurfaceLike, shp::Shape2, res::Tuple2{Intege
 
     return convert_arguments(P, xs, ys, lvs)
 end
-
-# Define the new signature of contour!() used in drawshape!() for 3D shapes.
-function Makie.convert_arguments(P::SurfaceLike, shp::Shape3,
-                                 cs::Tuple{Symbol,Real},  # (:x or :y or :z, intercept): cross section spec
-                                 res::Tuple2{Integer})
-    ax, cept = cs  # axis normal to cross section, intercept
-
-    ax==:x || ax==:y || ax==:z || @error "cs[1] = $(cs[1]) should be :x or :y or :z."
-    nw = (ax==:x) + 2(ax==:y) + 3(ax==:z)  # nw = 1, 2, 3 for ax = :x, :y, :z
-    nu, nv = mod1(nw+1,3), mod1(nw+2,3)
-
-    # Set the unit vectors along the u-, v-, w-axes.
-    û = SVec(ntuple(identity,Val(3))) .== nu
-    v̂ = SVec(ntuple(identity,Val(3))) .== nv
-    ŵ = SVec(ntuple(identity,Val(3))) .== nw
-
-    lower, upper = bounds(shp)
-    ∆ = upper - lower
-
-    ϵrel = EPS_REL
-    us = range(lower[nu] - ϵrel*∆[nu], upper[nu] + ϵrel*∆[nu], length=res[1])
-    vs = range(lower[nv] - ϵrel*∆[nv], upper[nv] + ϵrel*∆[nv], length=res[2])
-
-    lvs = [level(u*û + v*v̂ + cept*ŵ, shp) for u = us, v = vs]
-
-    return convert_arguments(P, us, vs, lvs)
-end