add video recording example (#152)

* don't create folder if not needed

* add example for recording a video

* remove old comment

* add more comments

* remove GL

* try our own tmpdir

* use GLWindow

examples/introduction/video_recording.jl

@@ -0,0 +1,47 @@
+using Colors, GLVisualize, GLAbstraction, GLWindow
+
+if !isdefined(:runtests)
+    window = glscreen()
+end
+description = """
+Example of how to record a video from GLVisualize
+"""
+kitty = visualize(loadasset("cat.obj"))
+_view(kitty, window)
+
+# save video to report dir, or in some tmp dir we'll delete later
+path = if haskey(ENV, "CI_REPORT_DIR")
+    ENV["CI_REPORT_DIR"] * "/videorecord.mkv"
+else
+    homedir()
+end
+name = ""
+while true # for some reason, folder retured by mktempdir isn't usable -.-
+    name = path * "/$(randstring()).mkv"
+    isfile(name) || break
+end
+
+# create a stream to which we can add frames
+io, buffer = GLVisualize.create_video_stream(name, window)
+for i=1:10 # record 10 frames
+    # do something
+    GLAbstraction.set_arg!(kitty, :color, RGBA{Float32}(1, 0, 1-(i/10), i/10))
+    #render current frame
+    # if you call @async renderloop(window) you can replace this part with yield
+    GLWindow.render_frame(window)
+    GLWindow.swapbuffers(window)
+    GLWindow.poll_reactive()
+
+    # add the frame from the current window
+    GLVisualize.add_frame!(io, window, buffer)
+end
+# closing the stream will trigger writing the video!
+close(io)
+
+if !isdefined(:runtests)
+    renderloop(window)
+end
+# clean up, only when we're not recording this!
+if !haskey(ENV, "CI_REPORT_DIR")
+    rm(name)
+end

test/test_static.jl

@@ -70,8 +70,10 @@ config = ExampleRunner.RunnerConfig(
 )
 window = config.window
 
-imgpath = joinpath(full_folder, "images")
-isdir(imgpath) || mkdir(imgpath)
+if recording
+    imgpath = joinpath(full_folder, "images")
+    isdir(imgpath) || mkdir(imgpath)
+end
 
 for path in config.files
     isopen(config.rootscreen) || break
@@ -117,7 +119,7 @@ end
 if recording
     open(joinpath(full_folder, "report.md"), "w") do io
         println(io, "### Test Images:")
-        create_mosaic(io, full_folder)
+        create_mosaic(io, imgpath)
         if !isempty(failures)
             println(io, "### Failures:")
             for (k, dict) in failures