Cameras

Overview

2D and 3D camera types that encapsulate position, orientation, and projection parameters. Functions are provided for constructing cameras, computing view and projection matrices, transforming points between spaces, and manipulating the camera through movement, rotation, zoom, and orbit.

Why Use This?

Camera types save you from manually managing view and projection matrices. They provide high-level helpers like world_to_screen, screen_to_world, and world_to_ndc so you can focus on gameplay and rendering logic rather than matrix math.

Camera 2D

Header: lm2/camera/lm2_camera2.h

A 2D orthographic camera defined by a world-space position, a counter-clockwise rotation, a uniform zoom factor, and a screen viewport rectangle.

Types

Type	Scalar	Description
`lm2_camera2_f64`	`double`	2D camera (double precision)
`lm2_camera2_f32`	`float`	2D camera (float precision)

Structure

typedef struct lm2_camera2_f32 {
    lm2_v2_f32 position;  // World-space center of the camera
    float      rotation;  // Counter-clockwise rotation in radians
    float      zoom;      // Uniform zoom factor (1.0 = no zoom)
    lm2_r2_f32 viewport;  // Screen viewport rectangle in pixels
} lm2_camera2_f32;

Functions

All functions shown with _f32 suffix. Also available with _f64.

Construction

Function	Description
`lm2_camera2_make_f32(position, rotation, zoom, viewport)`	Construct from all fields
`lm2_camera2_default_f32(viewport)`	Default camera: origin, no rotation, zoom 1

View Matrix

Function	Description
`lm2_camera2_get_view_f32(camera)`	3x2 view matrix (world → camera space)
`lm2_camera2_get_inv_view_f32(camera)`	3x2 inverse view matrix (camera → world space)

Space Transforms

Function	Description
`lm2_camera2_world_to_screen_f32(camera, world_pos)`	World-space point → screen pixels
`lm2_camera2_screen_to_world_f32(camera, screen_pos)`	Screen pixels → world-space point

Camera Manipulation

Function	Description
`lm2_camera2_move_f32(camera, delta)`	Translate camera by world-space delta
`lm2_camera2_zoom_at_f32(camera, zoom_factor, screen_anchor)`	Zoom in/out keeping a screen point fixed
`lm2_camera2_set_zoom_f32(camera, zoom)`	Set zoom to an absolute value
`lm2_camera2_rotate_f32(camera, delta_radians)`	Rotate by an angle delta

Viewport Helpers

Function	Description
`lm2_camera2_get_viewport_size_f32(camera)`	Viewport size in pixels
`lm2_camera2_get_viewport_center_f32(camera)`	Viewport center in pixels
`lm2_camera2_get_world_bounds_f32(camera)`	Visible world-space AABB

Example

#include <lm2/camera/lm2_camera2.h>

lm2_r2_f32 viewport = lm2_r2_from_min_max_f32(
    lm2_v2_zero_f32(),
    lm2_v2_make_f32(1280.0f, 720.0f)
);

lm2_camera2_f32 cam = lm2_camera2_default_f32(viewport);

// Pan the camera to center on a point
cam = lm2_camera2_move_f32(cam, lm2_v2_make_f32(100.0f, 50.0f));

// Zoom in towards the mouse cursor
cam = lm2_camera2_zoom_at_f32(cam, 1.1f, lm2_v2_make_f32(640.0f, 360.0f));

// Convert a mouse click to world coordinates
lm2_v2_f32 world_pos = lm2_camera2_screen_to_world_f32(cam, lm2_v2_make_f32(100.0f, 200.0f));

// Get the view matrix for rendering
lm2_m3x2_f32 view = lm2_camera2_get_view_f32(cam);

Camera 3D

Header: lm2/camera/lm2_camera3.h

A 3D camera supporting both perspective and orthographic projection, defined by a world-space position, a look-at target, an up hint, and projection parameters. Uses a right-handed coordinate system.

Types

Type	Scalar	Description
`lm2_camera3_f64`	`double`	3D camera (double precision)
`lm2_camera3_f32`	`float`	3D camera (float precision)

Projection Enum

typedef enum lm2_camera3_projection {
    LM2_CAMERA3_PERSPECTIVE,
    LM2_CAMERA3_ORTHOGRAPHIC,
} lm2_camera3_projection;