Use gifs to improve documentation. (#21)

Former-commit-id: 40e5ccedcf5d1ca8f0d5cc373ba3b3c4cc2d6c6a

docs/gen_doc_gifs.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+ROOT=`stack path --project-root`
+
+for src in $ROOT/examples/doc_*.hs; do
+  BASE=`basename $src .hs`
+  DST=$ROOT/docs/gifs/$BASE.gif
+  if [[ "$src" -nt "$DST" ]]; then
+    echo stack $src render -o $DST
+    stack $src render -o $DST
+  fi
+done

docs/gen_gallery.sh

@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
 
+ROOT=`stack path --project-root`
 EXAMPLES='boundingbox colormaps goo latex_basic latex_color latex_draw
           latex_wheel raster sphere sunflower tangent_and_normal vector_field'
 
@@ -7,18 +8,18 @@ WIDTH=640
 HEIGHT=$((WIDTH*9/16))
 FPS=30
 
-SRC_DIR=examples
-DST_DIR=docs/rendered
+SRC_DIR=$ROOT/examples
+DST_DIR=$ROOT/docs/rendered
 OPTS='--fps $FPS --width $WIDTH --height $HEIGHT'
 
-cat << EOF > docs/gallery.md
+cat << EOF > $ROOT/docs/gallery.md
 # Gallery
 This file is auto-generated by docs/render_all.sh. DO NOT EDIT.
 
 EOF
 
 for e in $EXAMPLES; do
-  cat << EOF >> docs/gallery.md
+  cat << EOF >> $ROOT/docs/gallery.md
 ## $e
 
 <details>