c3bb096b5b
Samples an animation at time t. Wraps t for loops. Finds the keyframe segment containing t and linearly interpolates per-bone angles. Returns frame with angles in degrees (intuitive for tests and callers; internal storage uses radians). Edge cases handled: - t = 0 returns first-keyframe values - t = duration returns last-keyframe values (no overshoot) - t > duration with loop=true wraps via modulo - Keyframes with disjoint bone-sets: each bone interpolated where available, snapped where only one side has it.
236 lines
8.4 KiB
Lua
236 lines
8.4 KiB
Lua
-- lib-core.puppet v0.1.0
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-- Skeletal animation: skeleton + bones + tracks + rest + keyframe
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-- + procedural + look-at constraint. No footplant in v0.1.
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local M = {}
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-- ====================================================================
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-- Module state (lib-singleton)
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-- ====================================================================
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local all_puppets = {} -- {[handle] = puppet_instance}
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local next_handle = 1
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-- ====================================================================
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-- Utility helpers
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-- ====================================================================
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local function deep_copy(t)
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if type(t) ~= "table" then return t end
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local copy = {}
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for k, v in pairs(t) do copy[k] = deep_copy(v) end
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return copy
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end
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local function clamp_angle_rad(a)
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-- Normalize to [-pi, pi]
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local pi = math.pi
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while a > pi do a = a - 2 * pi end
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while a < -pi do a = a + 2 * pi end
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return a
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end
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-- Subsequent tasks add: sample_animation,
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-- spawn, despawn, update, render, set_look_target, clear_look_target,
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-- bone_angle, set_procedural, clear_procedural, write_bone, play, stop,
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-- stop_all, is_playing, position, facing, move_to, register_animation,
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-- load_rig, load_animation.
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-- ====================================================================
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-- Rig validation + build
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-- ====================================================================
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function M.build_rig(rig_table)
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if type(rig_table) ~= "table" then
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error("puppet.build_rig: rig_table must be a table")
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end
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if type(rig_table.bones) ~= "table" or #rig_table.bones == 0 then
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error("puppet.build_rig: rig.bones must be a non-empty array")
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end
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if type(rig_table.tracks) ~= "table" then
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error("puppet.build_rig: rig.tracks must be an array")
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end
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-- Build bones_by_id with shallow copies of rest pose.
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local bones_by_id = {}
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for _, b in ipairs(rig_table.bones) do
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if type(b.id) ~= "string" then
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error("puppet.build_rig: bone.id must be string")
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end
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if bones_by_id[b.id] ~= nil then
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error("puppet.build_rig: duplicate bone id: " .. b.id)
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end
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bones_by_id[b.id] = {
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id = b.id,
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parent = nil, -- resolved below
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rest = {
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x = b.rest.x, y = b.rest.y,
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-- JSON angles in degrees; convert to radians once.
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angle = math.rad(b.rest.angle or 0),
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},
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look_at = (b.look_at == true),
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color = b.color or { 200, 200, 200 },
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}
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end
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-- Resolve parents (object references).
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for _, b_src in ipairs(rig_table.bones) do
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local b = bones_by_id[b_src.id]
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if b_src.parent ~= nil then
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local parent_obj = bones_by_id[b_src.parent]
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if parent_obj == nil then
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error("puppet.build_rig: parent '" .. tostring(b_src.parent)
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.. "' of bone '" .. b.id .. "' not found")
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end
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b.parent = parent_obj
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end
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end
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-- Build tracks + validate each bone is in EXACTLY ONE track.
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local bone_to_track = {}
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local tracks_by_id = {}
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for _, t in ipairs(rig_table.tracks) do
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if type(t.id) ~= "string" then
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error("puppet.build_rig: track.id must be string")
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end
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if tracks_by_id[t.id] ~= nil then
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error("puppet.build_rig: duplicate track id: " .. t.id)
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end
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local bones_in_track = {}
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for _, bid in ipairs(t.bones) do
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if bones_by_id[bid] == nil then
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error("puppet.build_rig: track '" .. t.id
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.. "' references unknown bone '" .. bid .. "'")
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end
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if bone_to_track[bid] ~= nil then
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error("puppet.build_rig: bone '" .. bid
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.. "' assigned to multiple tracks ('"
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.. bone_to_track[bid] .. "' and '" .. t.id .. "')")
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end
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bone_to_track[bid] = t.id
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bones_in_track[#bones_in_track + 1] = bid
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end
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tracks_by_id[t.id] = { id = t.id, bones = bones_in_track }
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end
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return {
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id = rig_table.id or "anonymous",
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bones = rig_table.bones, -- keep original-order array
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bones_by_id = bones_by_id,
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tracks_by_id = tracks_by_id,
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bone_to_track = bone_to_track,
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}
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end
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-- ====================================================================
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-- Animation validation + build
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-- ====================================================================
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function M.build_animation(anim_table, rig)
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if type(anim_table) ~= "table" then
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error("puppet.build_animation: anim_table must be a table")
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end
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if type(anim_table.track) ~= "string" then
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error("puppet.build_animation: animation.track must be string")
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end
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if rig.tracks_by_id[anim_table.track] == nil then
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error("puppet.build_animation: animation.track '"
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.. anim_table.track .. "' not found in rig")
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end
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if type(anim_table.duration) ~= "number" or anim_table.duration <= 0 then
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error("puppet.build_animation: animation.duration must be positive number")
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end
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if type(anim_table.keyframes) ~= "table" or #anim_table.keyframes == 0 then
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error("puppet.build_animation: animation.keyframes must be non-empty array")
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end
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-- Validate each keyframe: t in [0, duration], bones referenced are in this animation's track.
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local track_bones = {}
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for _, bid in ipairs(rig.tracks_by_id[anim_table.track].bones) do
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track_bones[bid] = true
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end
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local keyframes = {}
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for i, kf in ipairs(anim_table.keyframes) do
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if type(kf.t) ~= "number" or kf.t < 0 or kf.t > anim_table.duration + 1e-9 then
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error("puppet.build_animation: keyframe[" .. i .. "].t out of [0, duration]")
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end
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local cooked = { t = kf.t, bones = {} }
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for k, v in pairs(kf) do
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if k ~= "t" then
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if rig.bones_by_id[k] == nil then
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error("puppet.build_animation: keyframe references unknown bone '" .. k .. "'")
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end
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if not track_bones[k] then
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error("puppet.build_animation: keyframe writes bone '" .. k
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.. "' which is not in animation's track '" .. anim_table.track .. "'")
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end
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cooked.bones[k] = {
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angle = math.rad(v.angle or 0), -- JSON degrees → radians
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}
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end
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end
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keyframes[i] = cooked
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end
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return {
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id = anim_table.id or "anonymous",
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track = anim_table.track,
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duration = anim_table.duration,
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loop = (anim_table.loop == true),
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keyframes = keyframes,
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}
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end
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-- ====================================================================
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-- Animation sampling
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-- ====================================================================
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function M.sample_animation(anim, t)
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-- Wrap t for loops.
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if anim.loop and t > anim.duration then
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t = t % anim.duration
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end
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if t < 0 then t = 0 end
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if t > anim.duration then t = anim.duration end
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local kfs = anim.keyframes
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-- Find segment [kf_i, kf_{i+1}] containing t.
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local prev_kf, next_kf = kfs[1], kfs[1]
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for i = 1, #kfs - 1 do
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if t >= kfs[i].t and t <= kfs[i + 1].t then
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prev_kf = kfs[i]
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next_kf = kfs[i + 1]
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break
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end
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end
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-- If t equals last keyframe's t (or beyond and not looping), snap to last.
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if t >= kfs[#kfs].t then
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prev_kf = kfs[#kfs]
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next_kf = kfs[#kfs]
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end
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-- Linear interpolation per bone present in either keyframe.
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local frame = {}
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local span = next_kf.t - prev_kf.t
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local alpha = (span > 0) and ((t - prev_kf.t) / span) or 0
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local all_bones = {}
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for bid, _ in pairs(prev_kf.bones) do all_bones[bid] = true end
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for bid, _ in pairs(next_kf.bones) do all_bones[bid] = true end
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for bid, _ in pairs(all_bones) do
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local prev_v = prev_kf.bones[bid]
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local next_v = next_kf.bones[bid]
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if prev_v and next_v then
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frame[bid] = {
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angle = math.deg(prev_v.angle * (1 - alpha) + next_v.angle * alpha),
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}
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elseif prev_v then
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frame[bid] = { angle = math.deg(prev_v.angle) }
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elseif next_v then
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frame[bid] = { angle = math.deg(next_v.angle) }
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end
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end
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return frame
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end
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return M
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