# Space Stretch

SourceEdit
``````-- 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}
lovr.graphics.setBackgroundColor(palette[1])

function lovr.update(dt)
motion.left_anchor_vr:set(left_vr)
end
motion.right_anchor_vr:set(right_vr)
end
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
motion.pose:set()
motion.left_anchor_vr:set(left_vr)
motion.right_anchor_vr:set(right_vr)
end
end
end

function lovr.draw(pass)
pass: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 poseVR = mat4(motion.pose):mul(poseRW)
pass:setColor(palette[6])
else
pass:setColor(palette[8])
end
poseVR:scale(0.02)
pass:sphere(poseVR)
end
-- An example scene
local t = lovr.timer.getTime()
pass:setCullMode('back')
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)
pass:setColor(palette[2 + math.floor(y * 10) % (#palette - 1)])
pass:sphere(x, y, z, step / 2)
end
end
end
``````