diff --git a/README.md b/README.md
index 177bb34..f7a969f 100644
--- a/README.md
+++ b/README.md
@@ -16,15 +16,29 @@ scripting.
 In more practical terms, reanimate is a library for turning code like this:
 
 ```haskell
-main = reanimate $ docEnv $ playThenReverseA $ mkAnimation duration $ \t ->
-  partialSvg t $ pathify $ mkCircle radius
-  where duration = 2; radius = screenHeight/3
+main = reanimate $ docEnv $ playThenReverseA drawCircle
 ```
 
 ... into animations like this:
 
-![Draw Circle](docs/gifs/doc_playThenReverseA.gif)
+[![Draw Circle](https://i.imgur.com/C02hPw8.gif)](examples/doc_playThenReverseA.hs)
 
+# What is reanimate good at?
+
+## Vector graphics and math
+[![Tangent/Normal](https://i.imgur.com/w6gEkbl.gif)](examples/demo_tangent.hs)
+[![Fourier](https://i.imgur.com/pX4YRa4.gif)](examples/tut_glue_fourier.hs)
+
+## Mapping and tracing
+[![Geo JSON](https://i.imgur.com/OrKiOqF.gif)](videos/map-projection/gif.hs)
+[![Object tracing](https://i.imgur.com/Y6NsPWF.gif)](examples/tut_glue_potrace.hs)
+
+## Mathematical typesetting
+[![LaTeX](https://i.imgur.com/e6oO4wz.gif)](examples/tut_glue_latex.hs)
+
+## 2D physics and 3D graphics
+[![2D Physics](https://i.imgur.com/ZHUfWdp.gif)](examples/tut_glue_physics.hs)
+[![3D graphics](https://i.imgur.com/4wdtuJw.gif)](examples/tut_glue_povray.hs)
 
 # Prerequisites
 
@@ -62,22 +76,6 @@ animation source code, the browser window will automatically reload and show the
  * Design overview: https://reanimate.readthedocs.io/en/latest/glue_tut/
  * Gallery with source code: https://reanimate.readthedocs.io/en/latest/gallery/
 
-# Examples
-
-The example gifs are displayed at 25 fps.
-
-![Map projections](gifs/map.gif)
-![LaTeX wheel](gifs/latex_wheel.gif)
-![Sunflower](gifs/sunflower.gif)
-![Tangent](gifs/tangent.gif)
-![Goo](gifs/goo.gif)
-![Drawing LaTeX equations](gifs/latex_draw.gif)
-![Bounding boxes](gifs/bbox.gif)
-![Colorful LaTeX](gifs/latex_color.gif)
-![Bezier curves](gifs/bezier.gif)
-![Valentine's Day](gifs/valentine.gif)
-![Basic LaTeX](gifs/latex_basic.gif)
-
 # Authors
 
   * David Himmelstrup.
@@ -104,4 +102,4 @@ means.
 
 Completed animations are uploaded to the [Reanimated Science](https://www.youtube.com/channel/UCbZujyI7i6JbI-I0shPvDgg) channel.
 
-Animation snippets are uploaded to the [Reanimated Science Playground](https://www.youtube.com/channel/UCL7MwXLtQbhJeb6Ts3_HooA) channel.
+Animation snippets are uploaded to the [Reanimated Science Shorts](https://www.youtube.com/channel/UCL7MwXLtQbhJeb6Ts3_HooA) channel.
diff --git a/examples/demo_tangent.hs b/examples/demo_tangent.hs
new file mode 100755
index 0000000..ada6c79
--- /dev/null
+++ b/examples/demo_tangent.hs
@@ -0,0 +1,110 @@
+#!/usr/bin/env stack
+-- stack runghc --package reanimate
+{-# LANGUAGE OverloadedStrings #-}
+module Main(main) where
+
+import           Control.Lens                    ((^.))
+import           Control.Monad.State
+import qualified Data.Vector.Unboxed             as V
+import           Geom2D.CubicBezier              (AnyBezier (..), Point (..),
+                                                  evalBezierDeriv)
+import           Graphics.SvgTree                (Coord, Tree (..), mapTree,
+                                                  pathDefinition)
+import           Linear.Metric
+import           Linear.V2                       (V2 (..))
+import           Linear.Vector
+import           Reanimate
+import           Reanimate.Builtin.Documentation
+
+main :: IO ()
+main = reanimate $ docEnv $ mkAnimation 30 $ \t ->
+  let piSvg = pathify $ lowerTransformations $ center $ scale 10 $ latex "s" in
+  mkGroup
+  [ mkBackgroundPixel rtfdBackgroundColor
+  , piSvg
+  , drawTangent t piSvg ]
+
+drawTangent :: Double -> SVG -> SVG
+drawTangent alpha | alpha >= 1 = id
+drawTangent alpha = mapTree worker
+  where
+    worker (PathTree path) =
+      let (V2 posX posY, tangent) =
+            atPartial alpha $ toLineCommands $ path^.pathDefinition
+          normed@(V2 tangentX tangentY) = normalize tangent ^* 4
+          V2 midX midY = lerp 0.5 0 normed
+          V2 normVectX normVectY = normalize tangent ^* (svgWidth normalTxt*1.1)
+          tangentSvg =
+            translate (posX) (posY) $
+            rotate (unangle normed/pi*180 + 180) $
+            translate 0 (svgHeight tangentTxt/2) $
+            tangentTxt
+          normalSvg =
+            translate (posX) (posY) $
+            rotate (unangle normed/pi*180 + 90) $
+            translate (svgWidth normalTxt/2*1.1) (svgHeight normalTxt/2*1.3) $
+            normalTxt
+      in mkGroup
+      [ withStrokeWidth (defaultStrokeWidth) $
+        withStrokeColor "black" $
+        translate (posX-midX) (posY-midY) $
+        mkLine (0, 0) (tangentX, tangentY)
+      , withStrokeWidth (defaultStrokeWidth) $
+        withStrokeColor "black" $
+        translate (posX) (posY) $
+        mkLine (0, 0) (-normVectY, normVectX)
+      , withStrokeWidth (defaultStrokeWidth*2) $
+        withStrokeColor "white" $
+        tangentSvg
+      , withFillOpacity 1 $ withFillColor "black" $ withStrokeWidth 0 $
+        tangentSvg
+      , withStrokeWidth (defaultStrokeWidth*2) $
+        withStrokeColor "white" $
+        normalSvg
+      , withFillOpacity 1 $ withFillColor "black" $ withStrokeWidth 0 $
+        normalSvg
+      ]
+    worker t = t
+    tangentTxt = scale 1.1 $ center $ latex "tangent"
+    normalTxt = scale 1.1 $ center $ latex "normal"
+
+atPartial :: Double -> [LineCommand] -> (V2 Double, V2 Double)
+atPartial alpha cmds = evalState (worker 0 cmds) zero
+  where
+    worker _d [] = pure (0, 0)
+    worker d (cmd:xs) = do
+      from <- get
+      len <- lineLength cmd
+      let frac = (targetLen-d) / len
+      if len == 0 || frac >= 1
+        then worker (d+len) xs
+        else do
+          let bezier = lineCommandToBezier from cmd
+              (pos, tangent) = evalBezierDeriv bezier frac
+          pure $ (fromPoint pos, fromPoint tangent)
+    totalLen = evalState (sum <$> mapM lineLength cmds) zero
+    targetLen = totalLen * alpha
+
+lineCommandToBezier :: V2 Coord -> LineCommand -> AnyBezier Coord
+lineCommandToBezier from line =
+  case line of
+    LineBezier [a] ->
+      AnyBezier $ V.fromList [toTuple from, toTuple a]
+    LineBezier [a,b] ->
+      AnyBezier $ V.fromList [toTuple from, toTuple a, toTuple b]
+    LineBezier [a,b,c] ->
+      AnyBezier $ V.fromList [toTuple from, toTuple a, toTuple b, toTuple c]
+    _ -> error (show line)
+
+fromPoint :: Point a -> V2 a
+fromPoint (Point x y) = V2 x y
+
+toTuple :: V2 a -> (a,a)
+toTuple (V2 x y) = (x, y)
+
+unangle :: (Floating a, Ord a) => V2 a -> a
+unangle a@(V2 ax ay) =
+  let alpha = asin $ ay / norm a
+  in if ax < 0
+       then pi - alpha
+       else alpha
diff --git a/examples/tut_glue_fourier.hs b/examples/tut_glue_fourier.hs
index 3dbe5b7..0b4f15b 100755
--- a/examples/tut_glue_fourier.hs
+++ b/examples/tut_glue_fourier.hs
@@ -12,8 +12,9 @@ import           Codec.Picture
 
 -- layer 3
 main :: IO ()
-main = reanimate $ parA bg $ sceneAnimation $ do
-    play $ fourierA (fromToS 0 15)      -- Rotate 15 times
+main = reanimate $ setDuration 30 $ sceneAnimation $ do
+    _ <- newSpriteSVG $ mkBackgroundPixel (PixelRGBA8 252 252 252 0xFF)
+    play $ fourierA (fromToS 0 5)      -- Rotate 15 times
       # setDuration 50
       # signalA (reverseS . powerS 2 . reverseS) -- Start fast, end slow
       # pauseAtEnd 2
@@ -22,8 +23,6 @@ main = reanimate $ parA bg $ sceneAnimation $ do
       # reverseA
       # signalA (powerS 2)                       -- Start slow, end fast
       # pauseAtEnd 2
-  where
-    bg = animate $ const $ mkBackgroundPixel (PixelRGBA8 252 252 252 0xFF)
 
 -- layer 2
 fourierA :: (Double -> Double) -> Animation
diff --git a/examples/tut_glue_latex.hs b/examples/tut_glue_latex.hs
index 9565b3e..427b80c 100755
--- a/examples/tut_glue_latex.hs
+++ b/examples/tut_glue_latex.hs
@@ -25,7 +25,7 @@ latexExample = sceneAnimation $ do
     -- Draw equation
     play $ drawAnimation strokedSvg
     sprites <- forM glyphs $ \(fn, _, elt) ->
-      newSpriteA $ animate $ const $ fn elt
+      newSpriteSVG $ fn elt
     -- Yoink each glyph
     forM_ (reverse sprites) $ \sprite -> do
       spriteE sprite (overBeginning 1 $ aroundCenterE $ highlightE)
diff --git a/examples/tut_glue_potrace.hs b/examples/tut_glue_potrace.hs
index 9baac61..b3433a9 100755
--- a/examples/tut_glue_potrace.hs
+++ b/examples/tut_glue_potrace.hs
@@ -18,13 +18,10 @@ main = reanimate $ parA bg $ sceneAnimation $ do
     xRot <- newVar (-45)
     yRot <- newVar 220
     wf <- newSprite $ wireframe <$> unVar xRot <*> unVar yRot
-    tweenVar yRot spinDur (\t v -> fromToS v (v+60*3) $ curveS 2 (t/spinDur))
+    fork $ tweenVar yRot spinDur $ \v -> fromToS v (v+60*3) . curveS 2
     replicateM_ wobbles $ do
-      tweenVar xRot (wobbleDur/2) (\t v -> fromToS v (v+90) $ curveS 2 (t/(wobbleDur/2)))
-      fork $ do
-        wait (wobbleDur/2)
-        tweenVar xRot (wobbleDur/2) (\t v -> fromToS v (v-90) $ curveS 2 (t/(wobbleDur/2)))
-      wait wobbleDur
+      tweenVar xRot (wobbleDur/2) $ \v -> fromToS v (v+90) . curveS 2
+      tweenVar xRot (wobbleDur/2) $ \v -> fromToS v (v-90) . curveS 2
     destroySprite wf
     play $ mkAnimation drawDuration (\t -> partialSvg t (wireframe (-45) 220))
       # reverseA
diff --git a/examples/tut_glue_povray.hs b/examples/tut_glue_povray.hs
index a3ff75d..5e11a39 100755
--- a/examples/tut_glue_povray.hs
+++ b/examples/tut_glue_povray.hs
@@ -22,7 +22,8 @@ import           System.Random.Shuffle
 
 
 main :: IO ()
-main = reanimate $ parA bg $ sceneAnimation $ do
+main = reanimate $ sceneAnimation $ do
+    newSpriteSVG $ mkBackgroundPixel $ PixelRGBA8 252 252 252 0xFF
     zPos <- newVar 0
     xRot <- newVar 0
     zRot <- newVar 0
@@ -41,8 +42,6 @@ main = reanimate $ parA bg $ sceneAnimation $ do
     fork $ tweenVar zRot 9 $ \v -> fromToS v 360 . curveS 2
     wait 10
     tweenVar zPos 2 $ \v -> fromToS v 0 . curveS 3
-  where
-    bg = animate $ const $ mkBackgroundPixel $ PixelRGBA8 252 252 252 0xFF
 
 texture :: Double -> SVG
 texture t = frameAt (t*duration latexExample) latexExample
@@ -92,7 +91,7 @@ latexExample = sceneAnimation $ do
     -- Draw equation
     play $ drawAnimation strokedSvg
     sprites <- forM glyphs $ \(fn, _, elt) ->
-      newSpriteA $ animate $ const $ fn elt
+      newSpriteSVG $ fn elt
     -- Yoink each glyph
     forM_ (reverse sprites) $ \sprite -> do
       spriteE sprite (overBeginning 1 $ aroundCenterE $ highlightE)
diff --git a/misc/01_cube.py b/misc/01_cube.py
deleted file mode 100644
index 37914b9..0000000
--- a/misc/01_cube.py
+++ /dev/null
@@ -1,53 +0,0 @@
-# blender --background --python 01_cube.py -- </path/to/output/image> <resolution_percentage>
-
-import bpy
-import os
-import sys
-import math
-
-sys.path.append(os.path.dirname(os.path.abspath(__file__)))
-import utils
-
-
-def get_output_file_path() -> str:
-    return str(sys.argv[sys.argv.index('--') + 1]) 
-
-
-def get_resolution_percentage() -> int:
-    return int(sys.argv[sys.argv.index('--') + 2])
-
-
-if __name__ == "__main__":
-    # Args
-    output_file_path = get_output_file_path()
-    resolution_percentage = get_resolution_percentage()
-
-    # Setting
-    default_scene = bpy.context.scene
-    default_camera_object = bpy.data.objects["Camera"]
-
-    bpy.ops.object.empty_add(location=(0.0, 0, 0.0))
-    focus_target = bpy.context.object
-    bpy.ops.object.select_all(action='DESELECT')
-    default_camera_object.select_set(True)
-    focus_target.select_set(True)
-    bpy.ops.object.parent_set()
-    focus_target.rotation_mode = 'XYZ'
-    focus_target.rotation_euler = (0,0,0)
-    focus_target.keyframe_insert(data_path='rotation_euler', frame=1)
-    focus_target.rotation_euler = (0,0,math.pi*2)
-    focus_target.keyframe_insert(data_path='rotation_euler', frame=120)
-
-    for k in focus_target.animation_data.action.fcurves.find('rotation_euler', index=2).keyframe_points:
-        k.interpolation = 'LINEAR'
-    
-
-    num_samples = 32
-
-    utils.set_animation(default_scene, fps=60, frame_start=1, frame_end=120)
-
-    utils.set_cycles_renderer(default_scene, resolution_percentage, output_file_path, default_camera_object,
-                              num_samples, use_denoising=True)
-
-    # Rendering
-    bpy.ops.render.render(animation=True, write_still=True)
diff --git a/misc/bend.py b/misc/bend.py
deleted file mode 100644
index 29616fd..0000000
--- a/misc/bend.py
+++ /dev/null
@@ -1,45 +0,0 @@
-import os
-import math
-
-import bpy
-
-cam = bpy.data.objects['Camera']
-origin = bpy.data.objects['Cube']
-
-bpy.ops.object.select_all(action='DESELECT')
-origin.select_set(True)
-bpy.ops.object.delete()
-
-#bpy.ops.mesh.primitive_ico_sphere_add(subdivisions=4)
-#bpy.ops.mesh.primitive_uv_sphere_add()
-x = 0.9
-bpy.ops.mesh.primitive_plane_add()
-plane = bpy.context.object
-plane.scale = (1,1.778,1)
-plane.scale = (1,2,1)
-bpy.ops.object.shade_smooth()
-modifier = plane.modifiers.new(name='Subsurf', type='SUBSURF')
-modifier.levels = 5
-modifier.render_levels = 5
-modifier.subdivision_type = 'SIMPLE'
-
-bpy.ops.object.empty_add(type='ARROWS',rotation=(math.pi/2,0,0))
-empty = bpy.context.object
-
-bendUp = plane.modifiers.new(name='Bend up', type='SIMPLE_DEFORM')
-bendUp.deform_method = 'BEND'
-bendUp.origin = empty
-bendUp.deform_axis = 'Z'
-bendUp.factor = math.pi*x
-
-bendAround = plane.modifiers.new(name='Bend up', type='SIMPLE_DEFORM')
-bendAround.deform_method = 'BEND'
-bendAround.origin = empty
-bendAround.deform_axis = 'X'
-bendAround.factor = math.pi*2*x
-
-scn = bpy.context.scene
-# scn.render.engine = 'CYCLES'
-scn.render.film_transparent = True
-
-bpy.ops.render.render( write_still=True )
diff --git a/misc/test.py b/misc/test.py
deleted file mode 100644
index 1289cc1..0000000
--- a/misc/test.py
+++ /dev/null
@@ -1,43 +0,0 @@
-import os
-
-import bpy
-
-cam = bpy.data.objects['Camera']
-origin = bpy.data.objects['Cube']
-
-bpy.ops.object.select_all(action='DESELECT')
-origin.select_set(True)
-bpy.ops.object.delete()
-
-#bpy.ops.mesh.primitive_ico_sphere_add(subdivisions=4)
-bpy.ops.mesh.primitive_uv_sphere_add()
-bpy.ops.object.shade_smooth()
-
-# bpy.data.materials.new('Prog mat')
-bpy.context.object.active_material = bpy.data.materials['Material']
-mat = bpy.context.object.active_material
-image_node = mat.node_tree.nodes.new('ShaderNodeTexImage')
-texture = mat.node_tree.nodes['Principled BSDF']
-texture.inputs['Roughness'].default_value = 1
-mat.node_tree.links.new(image_node.outputs['Color'], texture.inputs['Base Color'])
-
-bpy.ops.image.open(filepath='/home/lemmih/Downloads/earth.jpg')
-image_node.image = bpy.data.images['earth.jpg']
-
-
-
-# image_node.image = bpy.data.images['earth.jpg']
-# bpy.ops.image.open(filepath='/home/lemmih/Downloads/earth.jpg')
-# image_node = mat.node_tree.nodes.new('ShaderNodeTexImage')
-# image_node = mat.node_tree.nodes[1]
-# texture = mat.node_tree.nodes[2]
-# mat.node_tree.links.new(image_node.outputs[0], texture.inputs[0])
-# bpy.data.materials.new('Prog mat')
-# bpy.context.object.active_material = bpy.data.materials['Prog mat']
-
-scn = bpy.context.scene
-# scn.render.engine = 'CYCLES'
-scn.render.film_transparent = True
-
-bpy.data.scenes["Scene"].render.filepath = '/tmp/blender.png'
-bpy.ops.render.render( write_still=True )
diff --git a/reanimate.cabal b/reanimate.cabal
index 979a761..5003632 100644
--- a/reanimate.cabal
+++ b/reanimate.cabal
@@ -91,7 +91,7 @@ library
                        JuicyPixels, attoparsec, parallel,
                        cubicbezier, websockets,
                        hashable, fsnotify, open-browser, random-shuffle, base64-bytestring,
-                       vector, colour, cassava, ansi-wl-pprint, here, temporary,
+                       vector >= 0.12.0.0, colour, cassava, ansi-wl-pprint, here, temporary,
                        optparse-applicative, chiphunk >= 0.1.2.1,
                        geojson, aeson >= 1.3.0.0
   ghc-options: -Wall
diff --git a/src/Reanimate/Builtin/Documentation.hs b/src/Reanimate/Builtin/Documentation.hs
index 8946e40..d2793c9 100644
--- a/src/Reanimate/Builtin/Documentation.hs
+++ b/src/Reanimate/Builtin/Documentation.hs
@@ -48,3 +48,6 @@ showColorMap f = center $ scaleToSize screenWidth screenHeight $ embedImage img
     height = 1
     img = generateImage pixelRenderer width height
     pixelRenderer x _y = f (fromIntegral x / fromIntegral (width-1))
+
+rtfdBackgroundColor :: PixelRGBA8
+rtfdBackgroundColor = PixelRGBA8 252 252 252 0xFF
diff --git a/stack.yaml b/stack.yaml
index 4b92e50..bc05ef6 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-13.14
+resolver: lts-13.19
 
 allow-newer: false
 
diff --git a/stack.yaml.lock b/stack.yaml.lock
index 9172026..de2ee5f 100644
--- a/stack.yaml.lock
+++ b/stack.yaml.lock
@@ -41,7 +41,7 @@ packages:
     hackage: matrices-0.5.0@sha256:b2761813f6a61c84224559619cc60a16a858ac671c8436bbac8ec89e85473058
 snapshots:
 - completed:
-    size: 497078
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/13/14.yaml
-    sha256: 9e5ba48e5188aeb52bb0df9bc65dbd858a12c33f5b8d495a3eb588dc9ffcb15a
-  original: lts-13.14
+    size: 498155
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/13/19.yaml
+    sha256: b9367a80d4393d02e58a46b8a9fdfbd7bc19f59c0c2bbf90034ba15cf52cf213
+  original: lts-13.19
diff --git a/videos/map-projection/gif.hs b/videos/map-projection/gif.hs
index b638840..e12030f 100644
--- a/videos/map-projection/gif.hs
+++ b/videos/map-projection/gif.hs
@@ -14,6 +14,7 @@ import           Reanimate
 import           Reanimate.Animation
 import           Reanimate.Scene
 import           Reanimate.GeoProjection
+import           Reanimate.Builtin.Documentation
 import           System.IO.Unsafe
 import           Data.Geospatial         hiding (LonLat)
 import           Data.LinearRing
@@ -27,8 +28,8 @@ import           Control.Lens            ((^.))
 
 
 main :: IO ()
-main = seq equirectangular $ reanimate $ sceneAnimation $ do
-    newSpriteSVG $ mkBackground "white"
+main = reanimate $ sceneAnimation $ do
+    newSpriteSVG $ mkBackgroundPixel rtfdBackgroundColor
     prevProj <- newVar equirectangularP
     let push label proj = do
           prev <- readVar prevProj
@@ -43,24 +44,24 @@ main = seq equirectangular $ reanimate $ sceneAnimation $ do
     --   [ grid equirectangularP ]
 
     -- push "Lambert" lambertP
-    push "Web Mercator" mercatorP
+    --push "Web Mercator" mercatorP
     push "Mollweide" mollweideP
-    -- push "Bottomley 30\\degree" (bottomleyP (toRads 30))
+    push "Bottomley 30\\degree" (bottomleyP (toRads 30))
     -- 4
-    -- pushInterp "Werner" wernerP
+    push "Werner" wernerP
     -- 5
-    -- pushInterp "Bonne 45\\degree" (bonneP (toRads 45))
+    -- push "Bonne 45\\degree" (bonneP (toRads 45))
     -- pushT
     --   (\t -> "Bonne " <> T.pack (show $ round $ fromToS 45 0 t) <> "\\degree")
     --   (bonneP . toRads . fromToS 45 0)
     -- 6
-    -- pushInterp "Eckert I" eckert1P
-    -- pushInterp "Eckert III" eckert3P
-    -- pushInterp "Eckert IV" eckert5P
+    -- push "Eckert I" eckert1P
+    -- push "Eckert III" eckert3P
+    -- push "Eckert IV" eckert5P
     -- 7
     -- push "Fahey" faheyP
     -- 8
-    push "August" augustP
+    -- push "August" augustP
     -- 9
     push "Foucaut" foucautP
     -- 10
@@ -70,17 +71,9 @@ main = seq equirectangular $ reanimate $ sceneAnimation $ do
     play $ signalA (curveS 2) $
       mkAnimation morphT $ grid . mergeP prev equirectangularP
   where
-    src = equirectangular
     waitT = 0
     morphT = 1
 
-equirectangular :: Image PixelRGB8
-equirectangular = unsafePerformIO $ do
-  dat <- BS.readFile "earth.jpg"
-  case decodeJpeg dat of
-    Left err  -> error err
-    Right img -> return $ convertRGB8 img
-
 toRads :: Double -> Double
 toRads dec = dec/180 * pi