From 759b6a4211a0344787fb82cbaa48c435baf76cfe Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Tue, 4 Aug 2026 23:21:11 +0300
Subject: [PATCH] add camera calculations

---
 src/camera.rs | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs    |  2 ++
 2 files changed, 80 insertions(+)
 create mode 100644 src/camera.rs

diff --git a/src/camera.rs b/src/camera.rs
new file mode 100644
index 0000000..f54059b
--- /dev/null
+++ b/src/camera.rs
@@ -0,0 +1,78 @@
+use glam::{Affine3A, Mat3, Mat4, vec3};
+
+pub(crate) fn rotation(yaw: f32, pitch: f32) -> Mat3 {
+	let (ys, yc) = yaw.sin_cos();
+	let (ps, pc) = pitch.sin_cos();
+	Mat3::from_cols_array_2d(&[[0., 0., -1.], [-1., 0., 0.], [0., 1., 0.]])
+		* Mat3::from_cols_array_2d(&[[pc, 0., -ps], [0., 1., 0.], [ps, 0., pc]])
+		* Mat3::from_cols_array_2d(&[[yc, -ys, 0.], [ys, yc, 0.], [0., 0., 1.]])
+}
+
+pub(crate) fn view(yaw: f32, pitch: f32, distance: f32) -> Affine3A {
+	Affine3A::from_mat3_translation(rotation(yaw, pitch), vec3(0., 0., distance))
+}
+
+pub(crate) fn projection(fovy: f32, aspect: f32) -> Mat4 {
+	Mat4::perspective_lh(fovy, aspect, 0.1, 10.0)
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	use glam::Vec3;
+	use std::f32::consts::PI;
+
+	#[test]
+	fn test_rotation() {
+		let mut ok = true;
+		for (yaw, pitch, x, y, z) in [
+			(0.0, 0.0, [0., 0., -1.], [-1., 0., 0.], [0., 1., 0.]),
+			(0.5, 0.0, [1., 0., 0.], [0., 0., -1.], [0., 1., 0.]),
+			(0.0, 0.5, [0., -1., 0.], [-1., 0., 0.], [0., 0., -1.]),
+			(0.5, 0.5, [1., 0., 0.], [0., -1., 0.], [0., 0., -1.]),
+		] {
+			let m = rotation(yaw * PI, pitch * PI);
+			if !m.abs_diff_eq(Mat3::from_cols_array_2d(&[x, y, z]), 1e-3) {
+				ok = false;
+				println!("Wrong rotation for {}, {}", 180. * yaw, 180. * pitch);
+				println!("X: expected: {}, actual: {}", Vec3::from_array(x), m.x_axis);
+				println!("Y: expected: {}, actual: {}", Vec3::from_array(y), m.y_axis);
+				println!("Z: expected: {}, actual: {}", Vec3::from_array(z), m.z_axis);
+			}
+		}
+		if !ok {
+			panic!();
+		}
+	}
+
+	#[test]
+	fn test_view() {
+		let mut ok = true;
+		for (yaw, pitch, x1, y1, z1) in [
+			(0.0, 0.0, [0., 0., 2.], [-1., 0., 3.], [0., 1., 3.]),
+			(0.5, 0.0, [1., 0., 3.], [0., 0., 2.], [0., 1., 3.]),
+			(0.0, 0.5, [0., -1., 3.], [-1., 0., 3.], [0., 0., 2.]),
+			(0.5, 0.5, [1., 0., 3.], [0., -1., 3.], [0., 0., 2.]),
+		] {
+			let m = view(yaw * PI, pitch * PI, 3.);
+			for (label, world, expected) in
+				[('X', Vec3::X, x1), ('Y', Vec3::Y, y1), ('Z', Vec3::Z, z1)]
+			{
+				let expected = Vec3::from_array(expected);
+				let actual = m.transform_point3(world);
+				if !actual.abs_diff_eq(expected, 1e-3) {
+					ok = false;
+					println!(
+						"Wrong transform for {}, {}: for {label}, expected: {expected}, got: {actual}",
+						180. * yaw,
+						180. * pitch
+					);
+				}
+			}
+		}
+		if !ok {
+			panic!();
+		}
+	}
+}
diff --git a/src/lib.rs b/src/lib.rs
index 294edfd..33f8d16 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,6 +2,8 @@ use std::error::Error;
 
 use glam::{UVec2, Vec4, vec4};
 
+mod camera;
+
 const DEPTH_FORMAT: wgpu::TextureFormat = wgpu::TextureFormat::Depth16Unorm;
 const OUTPUT_FORMAT: wgpu::TextureFormat = wgpu::TextureFormat::Bgra8UnormSrgb;