238 lines
7.9 KiB
Rust
238 lines
7.9 KiB
Rust
use glam::{Mat4, Quat, Vec3};
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use std::f32::consts::LN_2;
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use std::time::Instant;
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use winit::event::{ElementState, VirtualKeyCode};
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#[derive(Clone, Debug)]
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pub struct Camera {
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pub eye: [f32; 4],
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pub vp: [[f32; 4]; 4],
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}
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#[derive(Debug)]
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pub struct Flycam {
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// input
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// currently held keys
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is_world_up_pressed: bool,
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is_world_down_pressed: bool,
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is_cam_up_pressed: bool,
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is_cam_down_pressed: bool,
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is_forward_pressed: bool,
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is_backward_pressed: bool,
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is_left_pressed: bool,
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is_right_pressed: bool,
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// accumulated mouse movement yet to be processed
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mouse_dx: f32,
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mouse_dy: f32,
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// state
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// timestamp
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last_update: Instant,
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// camera orientation
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euler_x: f32,
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euler_y: f32,
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// camera movement state
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velocity: Vec3,
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position: Vec3,
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// constants
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// camera movement
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turn_sensitivity: f32, // coefficient for mouse_dx/dy -> euler_x/y
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thrust_mag: f32, // coefficient for thrust acceleration vector
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damping_coeff: f32, // coefficient for damping acceleration vector
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// camera frustum
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aspect: f32,
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fovy: f32,
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znear: f32,
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zfar: f32,
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}
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impl Flycam {
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/// thrust_speed: top speed when using a single thruster, in units/second
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/// duration to halve difference between current and target velocity, in seconds
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pub fn new(turn_sensitivity: f32, thrust_speed: f32, damper_half_life: f32) -> Self {
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Self {
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is_world_up_pressed: false,
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is_world_down_pressed: false,
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is_cam_up_pressed: false,
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is_cam_down_pressed: false,
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is_forward_pressed: false,
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is_backward_pressed: false,
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is_left_pressed: false,
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is_right_pressed: false,
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mouse_dx: 0.0,
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mouse_dy: 0.0,
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last_update: Instant::now(),
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euler_x: 0.0,
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euler_y: 0.0,
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velocity: Vec3::new(0.0, 0.0, 0.0),
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position: Vec3::new(0.0, 0.5, 1.0),
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turn_sensitivity,
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thrust_mag: thrust_speed / damper_half_life * LN_2,
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damping_coeff: LN_2 / damper_half_life,
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aspect: 1.0, // TODO compute from size
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fovy: std::f32::consts::FRAC_PI_2,
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znear: 0.01,
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zfar: 100.0,
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}
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}
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}
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impl Flycam {
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/// update stored keyboard state for use in update()
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pub fn process_keyboard(&mut self, key: VirtualKeyCode, state: ElementState) {
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let is_pressed = state == ElementState::Pressed;
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match key {
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VirtualKeyCode::Space => {
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self.is_world_up_pressed = is_pressed;
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}
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VirtualKeyCode::LShift => {
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self.is_world_down_pressed = is_pressed;
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}
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VirtualKeyCode::Q => {
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self.is_cam_down_pressed = is_pressed;
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}
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VirtualKeyCode::E => {
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self.is_cam_up_pressed = is_pressed;
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}
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VirtualKeyCode::W | VirtualKeyCode::Up => {
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self.is_forward_pressed = is_pressed;
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}
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VirtualKeyCode::A | VirtualKeyCode::Left => {
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self.is_left_pressed = is_pressed;
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}
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VirtualKeyCode::S | VirtualKeyCode::Down => {
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self.is_backward_pressed = is_pressed;
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}
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VirtualKeyCode::D | VirtualKeyCode::Right => {
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self.is_right_pressed = is_pressed;
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}
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_ => {}
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}
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}
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/// update accumulated mouse movement for use in update()
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pub fn process_mouse(&mut self, mouse_dx: f64, mouse_dy: f64) {
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self.mouse_dx += mouse_dx as f32;
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self.mouse_dy += mouse_dy as f32;
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}
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pub fn resize(&mut self, width: u32, height: u32) {
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self.aspect = (width as f32) / (height as f32);
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}
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/// apply input and update camera movement
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pub fn update(&mut self) {
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let dt = self.last_update.elapsed();
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self.last_update = Instant::now();
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let dt = dt.as_micros() as f32 / 1_000_000.0;
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self.update_orientation(dt);
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self.update_kinematic(dt);
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}
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fn update_orientation(&mut self, _dt: f32) {
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let t = self.turn_sensitivity;
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self.euler_x -= t * self.mouse_dy; // mouse +y = 2D plane down = look down = 3d space -x
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self.euler_y -= t * self.mouse_dx; // mouse +x = 2D plane right = look to the right = 3d space -y
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self.mouse_dx = 0.0;
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self.mouse_dy = 0.0;
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// Clamp euler_x to [-pi/2, pi/2]
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let euler_x_limit = std::f32::consts::FRAC_PI_2;
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if self.euler_x < -euler_x_limit {
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self.euler_x = -euler_x_limit;
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} else if self.euler_x > euler_x_limit {
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self.euler_x = euler_x_limit;
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}
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}
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/// update velocity and position from acceleration using forward differences
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fn update_kinematic(&mut self, dt: f32) {
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let net_acc = self.get_thrust_acc() + self.get_damping_acc();
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let delta_vel = net_acc * dt;
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self.velocity += delta_vel;
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let delta_pos = self.velocity * dt;
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self.position += delta_pos;
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}
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/// use keyboard key pairs to trigger directional thrusters in camera and world coordinates
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/// thrust_speed is the max speed (under drag) with a single thruster, but combinations can
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/// produce higher speeds (e.g. forward and right, camera down and world down)
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fn get_thrust_acc(&self) -> glam::Vec3 {
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let axis = Self::key_axis;
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let thruster_cam_x = axis(self.is_left_pressed, self.is_right_pressed);
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let thruster_cam_y = axis(self.is_cam_down_pressed, self.is_cam_up_pressed);
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let thruster_cam_z = -axis(self.is_backward_pressed, self.is_forward_pressed); // forward is -z
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let thruster_world_y = axis(self.is_world_down_pressed, self.is_world_up_pressed);
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let thrusters_cam = Vec3::new(thruster_cam_x, thruster_cam_y, thruster_cam_z);
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let thrusters_world = Vec3::new(0.0, thruster_world_y, 0.0);
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let cam_to_world = self.get_orientation();
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let thrusters_total = thrusters_world + cam_to_world * thrusters_cam;
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self.thrust_mag * thrusters_total
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}
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/// calculate a damping force (proportional to velocity)
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/// the damping coefficient is calculated in the constructor, which is parameterized in terms
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/// of more physically meaningful values
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fn get_damping_acc(&self) -> glam::Vec3 {
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self.damping_coeff * -self.velocity
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}
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/// a helper function to turn a pair of key states into a sign for thruster direction
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fn key_axis(negative: bool, positive: bool) -> f32 {
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if negative {
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if positive {
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0.0 // positive + negative cancel out
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} else {
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-1.0 // negative only
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}
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} else {
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if positive {
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1.0 // positive only
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} else {
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0.0 // neutral
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}
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}
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}
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/// the current camera orientation, which can be seen as a rotation (in quaternion form) from
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/// camera axes to world axes
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/// glam's YXZ ordering matches the standard roll-pitch-yaw Euler angles
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fn get_orientation(&self) -> glam::Quat {
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Quat::from_euler(glam::EulerRot::YXZ, self.euler_y, self.euler_x, 0.0)
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}
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pub fn get_camera(&self) -> Camera {
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Camera {
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eye: self.get_eye(),
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vp: self.get_vp()
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}
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}
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pub fn get_eye(&self) -> [f32; 4] {
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self.position.extend(0.0).to_array()
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}
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pub fn get_vp(&self) -> [[f32; 4]; 4] {
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// view matrix is inverted camera pose (world space to camera space)
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let rotation = Mat4::from_quat(self.get_orientation().inverse());
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let translation = Mat4::from_translation(-self.position);
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let view = rotation * translation;
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// perspective projection
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let proj = Mat4::perspective_rh_gl(self.fovy, self.aspect, self.znear, self.zfar);
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let vp = proj * view;
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vp.to_cols_array_2d()
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}
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}
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