Add example that detects thumbs up hand shape;

examples/Interaction/Hand_Gesture/main.lua

@@ -0,0 +1,100 @@
+lovr.filesystem.watch()
+
+local function getJointDirection(skeleton, joint)
+  return quat(unpack(skeleton[joint], 5)):direction()
+end
+
+local function getCurl(skeleton, finger)
+  local fingers = { thumb = 4, index = 8, middle = 13, ring = 18, pinky = 23 }
+  local jointCount = finger == 'thumb' and 2 or 3
+  local directions = {}
+
+  repeat
+    local orientation = quat(unpack(skeleton[fingers[finger] + #directions], 5))
+    table.insert(directions, orientation:direction())
+  until #directions == jointCount
+
+  local straightness = 0
+
+  for i = 2, jointCount do
+    straightness = straightness + math.max(directions[i]:dot(directions[i - 1]), 0)
+  end
+
+  local curliness = 1 - (straightness / (jointCount - 1))
+
+  return curliness
+end
+
+local function isThumbsUp(skeleton)
+  return skeleton and
+    getCurl(skeleton, 'thumb') < .1 and
+    getCurl(skeleton, 'index') > .6 and
+    getCurl(skeleton, 'middle') > .6 and
+    getCurl(skeleton, 'ring') > .6 and
+    getCurl(skeleton, 'pinky') > .6
+end
+
+function lovr.load()
+  hands = {
+    left = {},
+    right = {}
+  }
+end
+
+function lovr.update(dt)
+  for device, hand in pairs(hands) do
+    hand.skeleton = lovr.headset.getSkeleton(device)
+    hand.thumbsup = isThumbsUp(hand.skeleton)
+  end
+end
+
+local function drawSkeleton(pass, skeleton)
+  if not skeleton then return end
+
+  pass:setColor(0xf0f0f0)
+
+  for i, joint in ipairs(skeleton) do
+    pass:sphere(vec3(unpack(joint)), .01)
+  end
+
+  pass:setColor(0xb0b0b0)
+
+  for f = 1, 5 do
+    local base = ({ 3, 7, 12, 17, 22 })[f]
+    local length = f == 1 and 3 or 4
+    for j = 1, length do
+      local from = vec3(unpack(skeleton[base + j - 1]))
+      local to = vec3(unpack(skeleton[base + j - 0]))
+      pass:capsule(from, to, .002)
+    end
+  end
+end
+
+local function drawCurls(pass, skeleton, x)
+  if not skeleton then return end
+
+  pass:push()
+  pass:translate(x, 0, 0)
+  local str = 'curls:'
+  for i, finger in ipairs({ 'thumb', 'index', 'middle', 'ring', 'pinky' }) do
+    str = str .. ('\n%s: %.2f'):format(finger, getCurl(skeleton, finger))
+  end
+  pass:text(str, 0, 1.7, -2, .1)
+  pass:pop()
+end
+
+function lovr.draw(pass)
+  local str = 'Detecting thumbs up gesture..\n'
+
+  if hands.left.thumbsup or hands.right.thumbsup then
+    str = str .. 'Good job!'
+  end
+
+  pass:text(str, 0, 1.7, -2, .2)
+
+  drawSkeleton(pass, hands.left.skeleton)
+  drawSkeleton(pass, hands.right.skeleton)
+
+  drawCurls(pass, hands.left.skeleton, -2)
+  drawCurls(pass, hands.right.skeleton, 2)
+end