From 49cfc215a44182c001bf7b8a3ad9371a25dc3284 Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Sun, 18 Oct 2026 00:43:53 +0300
Subject: [PATCH] make field of view fixed regardless of view angle

---
 src/camera.rs          |  4 ++--
 src/lib.rs             | 17 +++++++----------
 ui/src/main_window.cxx |  4 ++--
 ui/src/main_window.ui  | 14 +++++++-------
 4 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/src/camera.rs b/src/camera.rs
index 17f69fe..4d3311c 100644
--- a/src/camera.rs
+++ b/src/camera.rs
@@ -12,8 +12,8 @@ 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_rh(fovy, aspect, 1.0, 100.0)
+pub(crate) fn projection(fovy: f32, aspect: f32, base_distance: f32) -> Mat4 {
+	Mat4::perspective_rh(fovy, aspect, 0.1 * base_distance, 10.0 * base_distance)
 }
 
 #[cfg(test)]
diff --git a/src/lib.rs b/src/lib.rs
index da85cfd..100daa0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -14,8 +14,8 @@ const BACKGROUND: Vec4 = vec4(0.00, 0.39, 0.52, 1.00);
 pub struct RedrawArgs {
 	pub cam_yaw: f32,
 	pub cam_pitch: f32,
-	pub cam_distance: f32,
-	pub cam_fovy: f32,
+	pub cam_view_y: f32,
+	pub cam_view_angle: f32,
 }
 
 impl Default for RedrawArgs {
@@ -23,8 +23,8 @@ impl Default for RedrawArgs {
 		Self {
 			cam_yaw: 3. * std::f32::consts::FRAC_PI_4,
 			cam_pitch: std::f32::consts::FRAC_PI_6,
-			cam_distance: 3.,
-			cam_fovy: std::f32::consts::FRAC_PI_2,
+			cam_view_y: 80.,
+			cam_view_angle: std::f32::consts::FRAC_PI_2,
 		}
 	}
 }
@@ -109,12 +109,9 @@ impl Core {
 			let h = size.height as f32;
 			w / h
 		};
-		let view = Mat4::from(camera::view(
-			args.cam_yaw,
-			args.cam_pitch,
-			args.cam_distance,
-		));
-		let proj = camera::projection(args.cam_fovy, aspect);
+		let distance = 0.5 * args.cam_view_y / (0.5 * args.cam_view_angle).tan();
+		let view = Mat4::from(camera::view(args.cam_yaw, args.cam_pitch, distance));
+		let proj = camera::projection(args.cam_view_angle, aspect, distance);
 		self.mesh_pipeline.set_params(
 			&self.queue,
 			render::mesh::Params {
diff --git a/ui/src/main_window.cxx b/ui/src/main_window.cxx
index 7ec4a2f..afd61d4 100644
--- a/ui/src/main_window.cxx
+++ b/ui/src/main_window.cxx
@@ -15,8 +15,8 @@ void GearCutter::updateView() {
 	RedrawArgs args{
 		.cam_yaw = qDegreesToRadians((float)m_ui->camYaw->value()),
 		.cam_pitch = qDegreesToRadians((float)m_ui->camPitch->value()),
-		.cam_distance = (float)m_ui->camDistance->value(),
-		.cam_fovy = qDegreesToRadians((float)m_ui->camFoV->value()),
+		.cam_view_y = (float)m_ui->camFoVLin->value(),
+		.cam_view_angle = qDegreesToRadians((float)m_ui->camFoVAng->value()),
 	};
 	m_ui->viewport->setView(args);
 }
diff --git a/ui/src/main_window.ui b/ui/src/main_window.ui
index fa127af..19d28a8 100644
--- a/ui/src/main_window.ui
+++ b/ui/src/main_window.ui
@@ -107,12 +107,12 @@
         <item>
          <widget class="QLabel" name="label_5">
           <property name="text">
-           <string>Distance</string>
+           <string>Linear size</string>
           </property>
          </widget>
         </item>
         <item>
-         <widget class="QDoubleSpinBox" name="camDistance">
+         <widget class="QDoubleSpinBox" name="camFoVLin">
           <property name="minimum">
            <double>10.000000000000000</double>
           </property>
@@ -123,19 +123,19 @@
            <enum>QAbstractSpinBox::StepType::AdaptiveDecimalStepType</enum>
           </property>
           <property name="value">
-           <double>40.000000000000000</double>
+           <double>80.000000000000000</double>
           </property>
          </widget>
         </item>
         <item>
          <widget class="QLabel" name="label_4">
           <property name="text">
-           <string>Field of view</string>
+           <string>Angular size</string>
           </property>
          </widget>
         </item>
         <item>
-         <widget class="QDoubleSpinBox" name="camFoV">
+         <widget class="QDoubleSpinBox" name="camFoVAng">
           <property name="suffix">
            <string> °</string>
           </property>
@@ -219,7 +219,7 @@
    </hints>
   </connection>
   <connection>
-   <sender>camDistance</sender>
+   <sender>camFoVLin</sender>
    <signal>valueChanged(double)</signal>
    <receiver>MainWindow</receiver>
    <slot>updateView()</slot>
@@ -235,7 +235,7 @@
    </hints>
   </connection>
   <connection>
-   <sender>camFoV</sender>
+   <sender>camFoVAng</sender>
    <signal>valueChanged(double)</signal>
    <receiver>MainWindow</receiver>
    <slot>updateView()</slot>