Support pan, rotate and zoom camera operations (#108)

* Support pan, rotate and zoom camera operations

* Add comments to Camera struct fields.

* Use quartenion rotation

* Adjust the conversion from mouse events to viewport change

* Fix CI

* Apply suggestions from code review

* get rotation working

* get pan working, fix making deltas relative to window size

* get zoom working

* make zooming work in ortho mode

* use MIN_ZOOM_FACTOR

* extend OrbitCamera::new with init_pos

* make clippy happy

* renormalize Quat after multiplication inside OrbitCamera

* revisit near and far clip values

* optimize a bit

* Update crates/viewer/src/camera.rs

---------

Co-authored-by: Máté Kovács <[email protected]>
Co-authored-by: Mate Kovacs <[email protected]>
Co-authored-by: Brian Schwind <[email protected]>

crates/viewer/src/camera.rs

@@ -1,4 +1,6 @@
-use glam::{vec3, Mat4};
+use glam::{Mat3, Mat4, Quat, Vec2, Vec3};
+
+const MIN_ZOOM_FACTOR: f32 = 0.05;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum Projection {
@@ -8,14 +10,33 @@ enum Projection {
     Perspective,
 }
 
-pub struct Camera {
+pub struct OrbitCamera {
     projection: Projection,
     aspect_ratio: f32,
+    // Zoom factor used for orthographic projection.
+    zoom_factor: f32,
+    // The look-at target, in the center of the view.
+    target: Vec3,
+    // The radius of the orbit
+    radius: f32,
+    // The orientation of the camera around the target point
+    orientation: Quat,
 }
 
-impl Camera {
-    pub fn new(width: u32, height: u32) -> Self {
-        Self { projection: Projection::Orthographic, aspect_ratio: width as f32 / height as f32 }
+impl OrbitCamera {
+    pub fn new(width: u32, height: u32, init_pos: Vec3) -> Self {
+        let target = Vec3::ZERO;
+        let radius = init_pos.length();
+        let look_at_matrix = Mat4::look_at_rh(init_pos, target, Vec3::Z);
+        let orientation = Quat::from_mat4(&look_at_matrix).inverse();
+        Self {
+            projection: Projection::Orthographic,
+            aspect_ratio: width as f32 / height as f32,
+            zoom_factor: 1.0,
+            target,
+            radius,
+            orientation,
+        }
     }
 
     pub fn resize(&mut self, width: u32, height: u32) {
@@ -30,29 +51,60 @@ impl Camera {
         self.projection = Projection::Orthographic;
     }
 
+    fn get_local_frame(&self) -> Mat3 {
+        Mat3::from_quat(self.orientation)
+    }
+
+    /// Pan the camera view horizontally and vertically. Look-at target will move along with the
+    /// camera.
+    pub fn pan(&mut self, delta: Vec2) {
+        self.target -= self.get_local_frame() * delta.extend(0.0);
+    }
+
+    /// Zoom in or out, while looking at the same target.
+    pub fn zoom(&mut self, zoom_delta: f32) {
+        self.zoom_factor = f32::max(self.zoom_factor * f32::exp(zoom_delta), MIN_ZOOM_FACTOR);
+    }
+
+    /// Orbit around the target while keeping the distance.
+    pub fn rotate(&mut self, rotator: Quat) {
+        self.orientation = (self.orientation * rotator).normalize();
+    }
+
     pub fn matrix(&self) -> Mat4 {
         // These magic numbers are configured so that the particular model we are loading is
         // visible in its entirety. They will be dynamically computed eventually when we have "fit
         // to view" function or alike.
-        let proj = match self.projection {
-            Projection::Orthographic => Mat4::orthographic_rh(
-                -100.0 * self.aspect_ratio,
-                100.0 * self.aspect_ratio,
-                -100.0,
-                100.0,
-                -1000.0,
-                1000.0,
-            ),
+
+        let (proj, effective_radius) = match self.projection {
+            Projection::Orthographic => {
+                let proj = Mat4::orthographic_rh(
+                    -50.0 * self.zoom_factor * self.aspect_ratio,
+                    50.0 * self.zoom_factor * self.aspect_ratio,
+                    -50.0 * self.zoom_factor,
+                    50.0 * self.zoom_factor,
+                    -1000.0,
+                    1000.0,
+                );
+                (proj, self.radius)
+            },
             Projection::Perspective => {
-                Mat4::perspective_rh(std::f32::consts::PI / 2.0, self.aspect_ratio, 0.01, 1000.0)
+                let proj = Mat4::perspective_rh(
+                    std::f32::consts::PI / 2.0,
+                    self.aspect_ratio,
+                    1.0,
+                    10_000.0,
+                );
+                (proj, self.zoom_factor * self.radius)
             },
         };
 
-        let view = Mat4::look_at_rh(
-            vec3(20.0, -30.0, 20.0), // Eye position
-            vec3(0.0, 0.0, 0.0),     // Look-at target
-            vec3(0.0, 0.0, 1.0),     // Up vector of the camera
-        );
+        let local_frame = self.get_local_frame();
+        let position = self.target + effective_radius * local_frame.z_axis;
+
+        // NOTE(mkovaxx): This is computing inverse(translation * orientation), but more efficiently
+        let view =
+            Mat4::from_quat(self.orientation.conjugate()) * Mat4::from_translation(-position);
 
         proj * view
     }

crates/viewer/src/main.rs

@@ -3,8 +3,9 @@ use crate::{
     surface_drawer::{CadMesh, SurfaceDrawer},
 };
 use anyhow::Error;
+use camera::OrbitCamera;
 use clap::{Parser, ValueEnum};
-use glam::{vec3, DVec3, Mat4};
+use glam::{vec2, vec3, DVec3, Mat4, Quat, Vec2, Vec3};
 use opencascade::primitives::Shape;
 use simple_game::{
     graphics::{
@@ -17,7 +18,8 @@ use simple_game::{
 use smaa::{SmaaMode, SmaaTarget};
 use std::path::PathBuf;
 use winit::{
-    event::{KeyEvent, WindowEvent},
+    dpi::PhysicalPosition,
+    event::{ElementState, KeyEvent, MouseButton, MouseScrollDelta::PixelDelta, WindowEvent},
     event_loop::EventLoopWindowTarget,
     keyboard::{KeyCode, PhysicalKey},
     window::Window,
@@ -27,10 +29,42 @@ mod camera;
 mod edge_drawer;
 mod surface_drawer;
 
-const MIN_SCALE: f32 = 0.01;
+// Multipliers to convert mouse position deltas to a more intuitve camera perspective change.
+const ZOOM_MULTIPLIER: f32 = 5.0;
+const TOUCHPAD_ZOOM_MULTIPLIER: f32 = 0.5;
+const ROTATE_MULTIPLIER: f32 = 8.0;
+const TOUCHPAD_ROTATE_MULTIPLIER: f32 = -0.05;
+const PAN_MULTIPLIER: f32 = 150.0;
+const TOUCHPAD_PAN_MULTIPLIER: f32 = 100.0;
+
+#[derive(Default)]
+struct MouseState {
+    left_button_down: bool,
+    middle_button_down: bool,
+    right_button_down: bool,
+    last_position: PhysicalPosition<f64>,
+}
+
+impl MouseState {
+    fn delta(&mut self, position: PhysicalPosition<f64>) -> (f64, f64) {
+        let delta = (position.x - self.last_position.x, position.y - self.last_position.y);
+        self.last_position = position;
+        delta
+    }
+
+    fn input(&mut self, button: MouseButton, state: ElementState) {
+        match button {
+            MouseButton::Left => self.left_button_down = state == ElementState::Pressed,
+            MouseButton::Middle => self.middle_button_down = state == ElementState::Pressed,
+            MouseButton::Right => self.right_button_down = state == ElementState::Pressed,
+            _ => {},
+        }
+    }
+}
 
 struct ViewerApp {
-    camera: camera::Camera,
+    client_rect: Vec2,
+    camera: OrbitCamera,
     depth_texture: DepthTexture,
     text_system: TextSystem,
     fps_counter: FPSCounter,
@@ -39,8 +73,7 @@ struct ViewerApp {
     smaa_target: SmaaTarget,
     rendered_edges: RenderedLine,
     cad_mesh: CadMesh,
-    angle: f32,
-    scale: f32,
+    mouse_state: MouseState,
 }
 
 #[derive(Parser, Debug, Clone)]
@@ -153,7 +186,8 @@ impl GameApp for ViewerApp {
         let depth_texture_format = depth_texture.format();
 
         Self {
-            camera: camera::Camera::new(width, height),
+            client_rect: vec2(width as f32, height as f32),
+            camera: OrbitCamera::new(width, height, Vec3::new(40.0, -40.0, 20.0)),
             depth_texture,
             text_system: TextSystem::new(device, surface_texture_format, width, height),
             fps_counter: FPSCounter::new(),
@@ -172,12 +206,12 @@ impl GameApp for ViewerApp {
             smaa_target,
             cad_mesh,
             rendered_edges,
-            angle: 0.0,
-            scale: 1.0,
+            mouse_state: Default::default(),
         }
     }
 
     fn resize(&mut self, graphics_device: &mut GraphicsDevice, width: u32, height: u32) {
+        self.client_rect = vec2(width as f32, height as f32);
         self.camera.resize(width, height);
         self.depth_texture = DepthTexture::new(graphics_device.device(), width, height);
         self.text_system.resize(width, height);
@@ -190,13 +224,53 @@ impl GameApp for ViewerApp {
         event: &WindowEvent,
         window_target: &EventLoopWindowTarget<()>,
     ) {
+        let screen_diagonal = self.client_rect.length();
+
         match event {
             WindowEvent::TouchpadRotate { delta, .. } => {
-                self.angle += 2.0 * delta * std::f32::consts::PI / 180.0;
+                let axis = Vec3::new(0.0, 0.0, 1.0);
+                let rotator = Quat::from_axis_angle(axis, TOUCHPAD_ROTATE_MULTIPLIER * delta);
+                self.camera.rotate(rotator);
+            },
+            WindowEvent::CursorMoved { position, .. } => {
+                let delta = self.mouse_state.delta(*position);
+                // On the screen, Y is DOWN, but in camera space, it's UP
+                let camera_space_delta =
+                    Vec2::new(delta.0 as f32, -delta.1 as f32) / screen_diagonal;
+                if self.mouse_state.left_button_down {
+                    // Construct the camera space rotation axis perpendicular to delta
+                    let axis = Vec3::new(camera_space_delta.y, -camera_space_delta.x, 0.0);
+                    let magnitude = axis.length();
+                    if magnitude > 0.0 {
+                        let rotator =
+                            Quat::from_axis_angle(axis.normalize(), ROTATE_MULTIPLIER * magnitude);
+                        self.camera.rotate(rotator);
+                    }
+                }
+                if self.mouse_state.middle_button_down {
+                    self.camera.pan(PAN_MULTIPLIER * camera_space_delta);
+                }
+                if self.mouse_state.right_button_down {
+                    self.camera.zoom(camera_space_delta.y * ZOOM_MULTIPLIER);
+                }
+            },
+            WindowEvent::MouseInput { state, button, .. } => {
+                self.mouse_state.input(*button, *state)
+            },
+            WindowEvent::MouseWheel { delta: PixelDelta(delta), .. } => {
+                // winit can not distinguish mouse wheel and touchpad pan events unfortunately.
+                // Because of that, we assign pan operation to MouseWheel events. For mice, you
+                // need to instead use mouse move while holding down the right button.
+
+                // On the screen, Y is DOWN, but in camera space, it's UP
+                let camera_space_delta =
+                    Vec2::new(delta.x as f32, -delta.y as f32) / screen_diagonal;
+
+                self.camera.pan(TOUCHPAD_PAN_MULTIPLIER * camera_space_delta);
             },
             WindowEvent::TouchpadMagnify { delta, .. } => {
-                self.scale += *delta as f32;
-                self.scale = self.scale.max(MIN_SCALE);
+                let zoom_delta = *delta as f32 * TOUCHPAD_ZOOM_MULTIPLIER;
+                self.camera.zoom(-zoom_delta);
             },
             WindowEvent::KeyboardInput {
                 event: KeyEvent { physical_key: PhysicalKey::Code(key_code), .. },
@@ -223,8 +297,7 @@ impl GameApp for ViewerApp {
         );
 
         let camera_matrix = self.camera.matrix();
-        let transform = Mat4::from_rotation_z(self.angle)
-            * Mat4::from_scale(vec3(self.scale, self.scale, self.scale));
+        let transform = Mat4::IDENTITY;
 
         self.surface_drawer.render(
             &mut frame_encoder.encoder,