Implemented a camera

1 files changed, 95 insertions, 0 deletions

diff --git a/src/camera.rs b/src/camera.rs
new file mode 100644
index 0000000..2eb1730
--- /dev/null
+++ b/src/camera.rs
@@ -0,0 +1,95 @@
+use cgmath::{Matrix4, Vector3};
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Camera {
+	position: (f32, f32),
+	zoom: f32,
+	rotation: f32,
+	inverse_aspect_ratio: f32,
+}
+
+pub(crate) type CameraUniform = [[f32; 4]; 4];
+
+#[allow(clippy::cast_precision_loss)]
+fn inverse_aspect_ratio(width: u32, height: u32) -> f32 {
+	(height as f32) / (width as f32)
+}
+
+impl Camera {
+	/// Create a new camera, with a position of (0, 0), and a zoom of 1.0
+	pub(crate) fn from_size(width: u32, height: u32) -> Self {
+		Self {
+			position: (0.0, 0.0),
+			zoom: 1.0,
+			rotation: 0.0,
+			inverse_aspect_ratio: inverse_aspect_ratio(width, height),
+		}
+	}
+
+	/// Get the camera's current x position
+	#[must_use]
+	pub const fn x(&self) -> f32 {
+		self.position.0
+	}
+
+	/// Get the camera's current y position
+	#[must_use]
+	pub const fn y(&self) -> f32 {
+		self.position.1
+	}
+
+	/// Get the camera's current zoom
+	#[must_use]
+	pub const fn zoom(&self) -> f32 {
+		self.zoom
+	}
+
+	/// Set the position of the camera
+	pub fn set_position(&mut self, x: f32, y: f32) {
+		self.position = (x, y);
+	}
+
+	/// Set the aspect ratio of the camera
+	pub fn set_zoom(&mut self, zoom: f32) {
+		self.zoom = zoom;
+	}
+
+	/// Set the aspect ratio of the camera
+	pub(crate) fn set_size(&mut self, width: u32, height: u32) {
+		self.inverse_aspect_ratio = inverse_aspect_ratio(width, height);
+	}
+
+	#[allow(clippy::wrong_self_convention)]
+	pub(crate) fn to_matrix(&mut self) -> [[f32; 4]; 4] {
+		let cos_theta = self.rotation.cos();
+		let sin_theta = self.rotation.sin();
+
+		let x_axis = Vector3::new(cos_theta, -sin_theta, 0.0);
+		let y_axis = Vector3::new(sin_theta, cos_theta, 0.0);
+		let z_axis = Vector3::new(0.0, 0.0, 1.0);
+
+		let eye = Vector3::new(self.position.0, self.position.1, 0.0);
+		let x_dot = -cgmath::dot(x_axis, eye);
+		let y_dot = -cgmath::dot(y_axis, eye);
+		let z_dot = -cgmath::dot(z_axis, eye);
+
+		#[rustfmt::skip]
+		let view_matrix = Matrix4::new(
+			x_axis.x, y_axis.x, z_axis.x, 0.0,
+			x_axis.y, y_axis.y, z_axis.y, 0.0,
+			x_axis.x, y_axis.y, z_axis.z, 0.0,
+			x_dot, y_dot, z_dot, 1.0
+		);
+
+		#[rustfmt::skip]
+		// TODO implement more scaling coordinate systems
+		let projection_matrix = Matrix4::new(
+			self.inverse_aspect_ratio, 0.0, 0.0, 0.0,
+			0.0, self.zoom, 0.0, 0.0,
+			0.0, 0.0, 0.0, 0.0,
+			0.0, 0.0, 0.0, 1.0
+		);
+
+		(projection_matrix * view_matrix).into()
+	}
+}