Merge pull request #71 from jmiskovic/add/space-stretch

A space-stretch locomotion example

examples/Locomotion/Space_Stretch/main.lua

@@ -0,0 +1,87 @@
+-- left grip + right grip: grab VR space and move / stretch / rotate
+-- left grip + right grip + right trigger: reset the view
+
+local motion = {
+  pose = lovr.math.newMat4(0,0,0, 1,1,1, 0, 0,1,0),
+  left_anchor_vr = lovr.math.newVec3(),
+  right_anchor_vr = lovr.math.newVec3(),
+}
+
+local palette = {0x0d2b45, 0x203c56, 0x544e68, 0x8d697a, 0xd08159, 0xffaa5e, 0xffd4a3, 0xffecd6}
+
+
+function lovr.update(dt)
+  local left_vr  = vec3(motion.pose:mul(lovr.headset.getPosition('hand/left')))
+  local right_vr = vec3(motion.pose:mul(lovr.headset.getPosition('hand/right')))
+  if lovr.headset.wasPressed('hand/left', 'grip') then
+    motion.left_anchor_vr:set(left_vr)
+  end
+  if lovr.headset.wasPressed('hand/right', 'grip') then
+    motion.right_anchor_vr:set(right_vr)
+  end
+  if lovr.headset.isDown('hand/left',  'grip') and
+     lovr.headset.isDown('hand/right', 'grip') then
+    local x, y, z, scale, _, _, angle, ax, ay, az = motion.pose:unpack()
+    -- Scale: get the ratio of distances between anchors over current controllers distance
+    local offset_scale = motion.left_anchor_vr:distance(motion.right_anchor_vr) / left_vr:distance(right_vr)
+    offset_scale = 1 + (offset_scale - 1)
+    scale = scale * offset_scale
+    -- the change of scale must also affect the viewpoint location
+    x, y, z = x * offset_scale, y * offset_scale, z * offset_scale
+    -- Position: the mid-point of anchors is compared to midpoint of current controllers position
+    local midpoint_anchor     = vec3(motion.left_anchor_vr):lerp(motion.right_anchor_vr, 0.5)
+    local midpoint_controller = vec3(left_vr):lerp(right_vr, 0.5)
+    local offset_position = vec3(midpoint_anchor):sub(midpoint_controller)
+    x, y, z = x + offset_position.x, y + offset_position.y, z + offset_position.z
+    motion.pose:set(x, y, z, scale, scale, scale, angle, ax, ay, az)  -- apply transition and scaling
+    -- Rotation: get angle between current controllers and anchors in XZ
+    local l_to_r_anchor = vec3(motion.right_anchor_vr):sub(motion.left_anchor_vr)
+    local l_to_r_controller = vec3(right_vr):sub(left_vr)
+    local sign = 1
+    if vec3(l_to_r_controller):cross(vec3(l_to_r_anchor)):dot(vec3(0, 1, 0)) < 0 then
+      sign = -1
+    end
+    l_to_r_anchor = l_to_r_anchor.xz:normalize()
+    l_to_r_controller = l_to_r_controller.xz:normalize()
+    local cos_angle = l_to_r_controller:dot(l_to_r_anchor)
+    cos_angle = math.max(-1, math.min(1, cos_angle))
+    local offset_rotation = math.acos(cos_angle) * sign
+    motion.pose:rotate(offset_rotation, 0,1,0) -- apply rotation
+    -- pose & anchor reset
+    if lovr.headset.isDown('hand/right', 'trigger') then
+      motion.pose:set()
+      motion.left_anchor_vr:set(left_vr)
+      motion.right_anchor_vr:set(right_vr)
+    end
+  end
+end
+
+
+function lovr.draw()
+  lovr.graphics.setBackgroundColor(palette[1])
+  lovr.graphics.transform(mat4(motion.pose):invert())
+  -- Render hands
+  for _, hand in ipairs(lovr.headset.getHands()) do
+    -- Whenever pose of hand or head is used, need to account for VR movement
+    local poseRW = mat4(lovr.headset.getPose(hand))
+    local poseVR = mat4(motion.pose):mul(poseRW)
+    if lovr.headset.isDown(hand, 'grip') then
+      lovr.graphics.setColor(palette[6])
+    else
+      lovr.graphics.setColor(palette[8])
+    end
+    poseVR:scale(0.02)
+    lovr.graphics.sphere(poseVR)
+  end
+  -- An example scene
+  local t = lovr.timer.getTime()
+  lovr.graphics.setCullingEnabled(true)
+  local step = 0.5
+  for x = -5, 5, step do
+    for z = -5, 5, step do
+      local y = 0.5 * math.sin(t * 0.2 + (x * 0.5)^2 + (z * 0.5)^2)
+      lovr.graphics.setColor(palette[2 + math.floor(y * 10) % (#palette - 1)])
+      lovr.graphics.sphere(x, y, z, step / 2)
+    end
+  end
+end

examples/init.lua

@@ -17,6 +17,7 @@ return {
   'Locomotion/Teleportation_Flat',
   'Locomotion/Teleportation_Colliders',
   'Locomotion/Walking_In_Place',
+  'Locomotion/Space_Stretch',
   'Environment/Grid',
   'Environment/Skybox',
   'Environment/Terrain_-_Heightmap',