Add naive depth sorting for scatter & text (#3432)

* add naive depth sorting for scatter & text

* add depthsorting docs

* update news

GLMakie/src/drawing_primitives.jl

@@ -572,6 +572,7 @@ function draw_atomic(screen::Screen, scene::Scene,
         gl_attributes[:distancefield] = get_texture!(atlas)
         gl_attributes[:visible] = plot.visible
         gl_attributes[:fxaa] = get(plot, :fxaa, Observable(false))
+        gl_attributes[:depthsorting] = get(plot, :depthsorting, false)
         cam = scene.camera
         # gl_attributes[:preprojection] = Observable(Mat4f(I))
         gl_attributes[:preprojection] = lift(plot, space, markerspace, cam.projectionview, cam.resolution) do s, ms, pv, res

GLMakie/src/glshaders/particles.jl

@@ -176,6 +176,20 @@ function draw_scatter(screen, (marker, position), data)
     rot = vec2quaternion(rot)
     delete!(data, :rotation)
 
+    if to_value(pop!(data, :depthsorting, false))
+        data[:indices] = map(
+            data[:projectionview], data[:preprojection], data[:model],
+            position
+        ) do pv, pp, m, pos
+            T = pv * pp * m
+            depth_vals = map(pos) do p
+                p4d = T * to_ndim(Point4f, to_ndim(Point3f, p, 0f0), 1f0)
+                p4d[3] / p4d[4]
+            end
+            UInt32.(sortperm(depth_vals, rev = true) .- 1)
+        end |> indexbuffer
+    end
+
     @gen_defaults! data begin
         shape       = Cint(0)
         position    = position => GLBuffer
@@ -194,6 +208,7 @@ function draw_scatter(screen, (marker, position), data)
             return shape
         end
     end
+
     @gen_defaults! data begin
         quad_offset     = Vec2f(0) => GLBuffer
         intensity       = nothing => GLBuffer
@@ -226,6 +241,7 @@ function draw_scatter(screen, (marker, position), data)
         scale_primitive = true
         gl_primitive = GL_POINTS
     end
+
     # Exception for intensity, to make it possible to handle intensity with a
     # different length compared to position. Intensities will be interpolated in that case
     data[:intensity] = intensity_convert(intensity, position)

NEWS.md

@@ -2,6 +2,7 @@
 
 ## master
 
+- Add `depthsorting` as a hidden attribute for scatter plots in GLMakie as an alternative fix for outline artifacts. [#3432](https://github.com/MakieOrg/Makie.jl/pull/3432)
 - Disable SDF based anti-aliasing in scatter, text and lines plots when `fxaa = true` in GLMakie. This allows removing outline artifacts at the cost of quality. [#3408](https://github.com/MakieOrg/Makie.jl/pull/3408)
 - DataInspector Fixes: Fixed depth order, positional labels being in transformed space and `:inspector_clear` not getting called when moving from one plot to another. [#3454](https://github.com/MakieOrg/Makie.jl/pull/3454)
 - Fixed bug in GLMakie where the update from a (i, j) sized GPU buffer to a (j, i) sized buffer would fail [#3456](https://github.com/MakieOrg/Makie.jl/pull/3456).

docs/reference/plots/scatter.md

@@ -378,6 +378,7 @@ Currently there are a few ways to mitigate this problem, but they all come at a
 - `fxaa = true` will disable the native anti-aliasing of scatter markers and use fxaa instead. This results in less detailed markers, especially for thin markers like characters.
 - `transparency = true` will disable depth testing to a degree, resulting in all markers being rendered without artifacts. However with this markers always have some level of transparency
 - `overdraw = true` will disable depth testing entirely (read and write) for the plot, removing artifacts. This will however change the z-order of markers and allow plots rendered later to show up on top of the scatter plot
+- `depthsorting = true` will sort markers by depth before rendering to fix the issue. This only works within a plot call, so when other plots are involved the issue may reappear.
 
 \begin{examplefigure}{}
 ```julia
@@ -386,15 +387,22 @@ GLMakie.activate!() # hide
 
 ps = rand(Point3f, 500)
 cs = rand(500)
-f = Figure(size = (600, 650))
+f = Figure(size = (900, 650))
 Label(f[1, 1], "base", tellwidth = false)
 scatter(f[2, 1], ps, color = cs, markersize = 20, fxaa = false)
 Label(f[1, 2], "fxaa = true", tellwidth = false)
 scatter(f[2, 2], ps, color = cs, markersize = 20, fxaa = true)
+
 Label(f[3, 1], "transparency = true", tellwidth = false)
 scatter(f[4, 1], ps, color = cs, markersize = 20, transparency = true)
 Label(f[3, 2], "overdraw = true", tellwidth = false)
 scatter(f[4, 2], ps, color = cs, markersize = 20, overdraw = true)
+
+Label(f[1, 3], "depthsorting = true", tellwidth = false)
+scatter(f[2, 3], ps, color = cs, markersize = 20, depthsorting = true)
+Label(f[3, 3], "depthsorting = true", tellwidth = false)
+scatter(f[4, 3], ps, color = cs, markersize = 20, depthsorting = true)
+mesh!(Rect3f(Point3f(0), Vec3f(0.9, 0.9, 0.9)), color = :orange)
 f
 ```
 \end{examplefigure}