tiny.rig.JointClip

1pub const JointClip = struct {2    /// Keys per second.3    rate: f32,4    /// Keys in every channel that is not constant.5    frames: u32,6    interpolation: Interpolation = .linear,7    channels: []const Channel,8    rotations: []const Quat = &.{},9    translations: []const Vec3 = &.{},10    part_channels: []const PartChannel = &.{},11    choices: []const u8 = &.{},1213    /// Checks every channel against the key slices and the joint and slot14    /// counts it will be sampled into. Sampling assumes a clip that passed.15    pub fn check(clip: JointClip, joint_count: usize, slot_count: usize) Error!void {16        if (!std.math.isFinite(clip.rate) or !(clip.rate > 0)) return error.InvalidRate;17        if (clip.frames == 0) return error.InvalidFrames;18        for (clip.channels) |channel| {19            if (channel.joint >= joint_count) return error.InvalidTarget;20            const keys = switch (channel.target) {21                .rotation => clip.rotations.len,22                .translation => clip.translations.len,23            };24            try checkKeys(clip.frames, channel.first, channel.count, keys);25        }26        for (clip.part_channels) |channel| {27            if (channel.slot >= slot_count) return error.InvalidTarget;28            try checkKeys(clip.frames, channel.first, channel.count, clip.choices.len);29        }30    }3132    /// Seconds from the first key to the first key again, for a loop.33    pub fn period(clip: JointClip) f64 {34        return @as(f64, @floatFromInt(clip.frames)) / clip.rate;35    }3637    /// Seconds from the first key to the last.38    pub fn span(clip: JointClip) f64 {39        return @as(f64, @floatFromInt(clip.frames - 1)) / clip.rate;40    }4142    /// The keys on either side of `time`. A time within43    /// `time.boundary_tolerance` of a key counts as on it, so sampling at44    /// `k / rate` returns key `k` exactly.45    pub fn position(clip: JointClip, time: f64, loop: bool) Position {46        assert(clip.frames > 0);47        assert(std.math.isFinite(time));48        const frames: f64 = @floatFromInt(clip.frames);49        var key = time * clip.rate;50        var base: f64 = undefined;51        if (loop) {52            key = @mod(key, frames);53            base = time_position.floorSnapped(key);54            if (base >= frames) {55                base -= frames;56                key -= frames;57            }58        } else {59            key = std.math.clamp(key, 0, frames - 1);60            base = time_position.floorSnapped(key);61        }62        const lower: u32 = @intFromFloat(base);63        assert(lower < clip.frames);64        const upper = if (lower + 1 < clip.frames) lower + 1 else if (loop) 0 else lower;65        const fraction: f32 = switch (clip.interpolation) {66            .step => 0,67            .linear => @floatCast(std.math.clamp(key - base, 0, 1)),68        };69        return .{70            .lower = lower,71            .upper = upper,72            .fraction = @min(fraction, 1 - std.math.floatEps(f32)),73        };74    }7576    /// The local transforms at `time`: `rest` where no channel applies.77    pub fn sample(78        clip: JointClip,79        time: f64,80        loop: bool,81        rest: []const Transform,82        local: []Transform,83    ) void {84        assert(local.len == rest.len);85        @memcpy(local, rest);86        const at = clip.position(time, loop);87        for (clip.channels) |channel| {88            assert(channel.joint < local.len);89            const lower = channel.first + if (channel.count == 1) 0 else at.lower;90            const upper = channel.first + if (channel.count == 1) 0 else at.upper;91            const joint = &local[channel.joint];92            switch (channel.target) {93                .rotation => joint.rotation = rotationAt(94                    clip.rotations[lower],95                    clip.rotations[upper],96                    at.fraction,97                ),98                .translation => joint.translation = translationAt(99                    clip.translations[lower],100                    clip.translations[upper],101                    at.fraction,102                ),103            }104        }105    }106107    /// Each part channel's choice at `time`, written to its slot. Slots108    /// without a channel keep what `choices` held.109    pub fn selectParts(clip: JointClip, time: f64, loop: bool, choices: []u8) void {110        const at = clip.position(time, loop);111        for (clip.part_channels) |channel| {112            assert(channel.slot < choices.len);113            const key = channel.first + if (channel.count == 1) 0 else at.lower;114            choices[channel.slot] = clip.choices[key];115        }116    }117};

1pub const JointClip = clip.JointClip;