Struct Camera 

pub struct Camera {
    pub position: Vec2,
    pub zoom: f32,
    pub rotation: f32,
    pub viewport: Option<(u32, u32)>,
    pub layer_parallax: FxHashMap<i32, Vec2>,
    pub target: Option<RenderTargetId>,
}

camera resource, affects how the render queue is projected.

when no camera resource exists, rendering uses world-space anchored at origin. when present, the orthographic projection is offset and scaled accordingly.

example

use lunar_render::Camera;
use lunar_math::Vec2;

// camera centered at (400, 300), letterboxed to an 800x600 viewport
let cam = Camera {
    position: Vec2::new(400.0, 300.0),
    zoom: 1.0,
    rotation: 0.0,
    viewport: Some((800, 600)),
    layer_parallax: Default::default(),
    target: None,
};

// use cam.projection_matrix(window_w, window_h) for the render projection

Fields

position: Vec2

camera position in world space

zoom: f32

zoom level (1.0 = 1:1, 2.0 = 2x zoom)

rotation: f32

rotation in radians

viewport: Option<(u32, u32)>

viewport size in pixels (None = full window)

layer_parallax: FxHashMap<i32, Vec2>

per-layer offset for parallax scrolling (layer id → world offset)

target: Option<RenderTargetId>

render target to draw into (None = swapchain / window)

Implementations

impl Camera

pub fn new() -> Self

create a new camera at the origin with default settings

pub fn at_position(x: f32, y: f32) -> Self

create a camera at the given position

pub fn projection_matrix( &self, window_width: u32, window_height: u32, ) -> [f32; 16]

compute the orthographic projection matrix incorporating camera transforms. returns a 4x4 column-major matrix as a flat array of 16 f32s. for per-layer parallax, use Camera::projection_matrix_for_layer instead.

example

use lunar_render::Camera;

let cam = Camera::default();
let proj = cam.projection_matrix(800, 600);
// proj is a [f32; 16] suitable for wgpu uniform upload

pub fn projection_matrix_for_layer( &self, layer: i32, window_width: u32, window_height: u32, ) -> [f32; 16]

compute the orthographic projection matrix with a per-layer parallax offset. the layer’s parallax offset is subtracted from the camera position before computing the transform, so layers can scroll at different speeds. set per-layer offsets via Camera::set_layer_parallax.

pub fn set_layer_parallax(&mut self, layer: i32, offset: Vec2)

set a parallax offset for a specific layer. the offset is a world-space Vec2 subtracted from the camera position when rendering that layer. to scroll a background at half speed, pass camera.position * 0.5 as the offset each frame.

pub fn clear_layer_parallax(&mut self, layer: i32)

remove the parallax offset for a layer, reverting to normal camera tracking.

pub fn screen_to_world( &self, screen: Vec2, window_width: u32, window_height: u32, ) -> Vec2

convert a screen-space pixel position to world-space coordinates.

accounts for camera position, zoom, rotation, and viewport letterboxing. screen origin is top-left, y-down. world is top-left, y-down.

example

fn my_system(camera: Res<Camera>, input: Res<InputState>) {
    let (mx, my) = input.mouse_position();
    let world = camera.screen_to_world(Vec2::new(mx, my), 800, 600);
    // spawn something at the mouse position in world space
}

pub fn world_to_screen( &self, world: Vec2, window_width: u32, window_height: u32, ) -> Vec2

convert a world-space position to screen-space pixel coordinates.

inverse of screen_to_world. the result is in screen pixel coordinates (top-left origin, y-down).

pub fn set_target_aspect(&mut self, width: u32, height: u32) -> &mut Self

enable or disable viewport letterboxing.

when enabled, the projection auto-computes black-bar offsets when the window aspect ratio doesn’t match the viewport aspect ratio. this is called internally by set_target_aspect.

returns &mut Self for chaining.

Trait Implementations

impl Clone for Camera

fn clone(&self) -> Camera

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for Camera

fn default() -> Self

Returns the “default value” for a type.

impl Resource for Camera

where Self: Send + Sync + 'static,