1 files changed, 95 insertions, 0 deletions
diff --git a/benoit-cli/src/keyframe/keyframe_interpolater/mod.rs b/benoit-cli/src/keyframe/keyframe_interpolater/mod.rs
new file mode 100644
index 0000000..3faa546
--- /dev/null
+++ b/benoit-cli/src/keyframe/keyframe_interpolater/mod.rs
@@ -0,0 +1,95 @@
+/*
+	Copyright 2021, 2023-2024 Gabriel Bjørnager Jen-
+	sen.
+
+	This file is part of benoit-cli.
+
+	benoit-cli is free software: you can redistrib-
+	ute it and/or modify it under the terms of the
+	GNU General Public License as published by the
+	Free Software Foundation, either version 3 of
+	the License, or (at your option) any later ver-
+	sion.
+
+	benoit-cli is distributed in the hope that it
+	will be useful, but WITHOUT ANY WARRANTY; with-
+	out even the implied warranty of MERCHANTABILITY
+	or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+	General Public License for more details.
+
+	You should have received a copy of the GNU Gene-
+	ral Public License along with benoit-cli. If
+	not, see <https://www.gnu.org/licenses/>.
+*/
+
+use crate::keyframe::Keyframe;
+
+use benoit::complex::Complex;
+use rug::Float;
+
+/// Interpolater between keyframes.
+///
+/// This is done as an iterator over the interpolated values.
+#[derive(Clone, Debug)]
+pub struct KeyframeInterpolater {
+	pub(in super) frame:      Option<u32>,
+	pub(in super) last_frame: u32,
+
+	pub(in super) max_iter_count: u64,
+	pub(in super) centre:         Complex,
+	pub(in super) seed:           Complex,
+	pub(in super) zoom:           Float,
+	pub(in super) colour_range:   f64,
+
+	pub(in super) max_iter_count_step: i64,
+	pub(in super) centre_step:         Complex,
+	pub(in super) seed_step:           Complex,
+	pub(in super) zoom_factor:         Float,
+	pub(in super) colour_range_step:   f64,
+}
+
+impl KeyframeInterpolater {
+	/// Advances the contained values to the next step.
+	///
+	/// # Panics
+	///
+	/// Panics if overflow occurs when calculating the new maximum iteration count.
+	/// This is guaranteed to not happen as long as the iterator hasn't been completed.
+	pub(in super) fn advance_values(&mut self) {
+		self.max_iter_count = self.max_iter_count
+			.checked_add_signed(self.max_iter_count_step)
+			.unwrap();
+
+		self.centre.real  += &self.centre_step.real;
+		self.centre.imag  += &self.centre_step.imag;
+		self.seed.real    += &self.seed_step.real;
+		self.seed.imag    += &self.seed_step.imag;
+		self.zoom         *= &self.zoom_factor;
+		self.colour_range += self.colour_range_step;
+	}
+}
+
+impl Iterator for KeyframeInterpolater {
+	type Item = Keyframe;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		let frame = self.frame?;
+		assert!(frame <= self.last_frame);
+
+		let keyframe = Keyframe {
+			frame,
+			max_iter_count: self.max_iter_count,
+			centre:         self.centre.clone(),
+			seed:           self.seed.clone(),
+			zoom:           self.zoom.clone(),
+			colour_range:   self.colour_range,
+		};
+
+		self.frame = (frame != self.last_frame).then(|| {
+			self.advance_values();
+			frame + 0x1
+		});
+
+		Some(keyframe)
+	}
+}