reliquary/plugins/bevy/skills/bevy-0.19/references/camera-rendering.md

Camera, Rendering, Assets

Camera setup

Camera3d is a marker with #[require(...)] pulling in Camera, DebandDither, CameraRenderGraph, Projection, Tonemapping, ColorGrading, Exposure. Spawning bare Camera3d yields a working 3D camera.

• 0.18: RenderTarget is a separate required component, no longer a Camera field.
• 0.19: Hdr moved from bevy_render to bevy_camera; screen-space specular transmission fields moved into a ScreenSpaceTransmission component.

Multiple cameras / ordering

• Camera.order: isize — higher renders later (on top).
• Every camera with is_active: true renders independently.
• Overlay cameras need ClearColorConfig::None or they wipe the layer below.

Camera gotchas

• Default far plane is 1000 units — anything beyond is silently culled.
• Forward is -Z.
• Viewport coordinates are physical pixels; cursor position is logical.

Coordinate system

Right-handed:

Axis	Bevy	GLTF models
Forward	-Z (Transform::forward())	+Z (Transform::back())
Up	+Y	+Y
Right	+X	-X from camera perspective

GLTF fix: orient with look_to(-direction, Vec3::Y) or treat transform.back() as the model's visual forward.

0.18: GltfPlugin's use_model_forward_direction was replaced by convert_coordinates with rotate_scene_entity and rotate_meshes flags.

Meshes & materials

• StandardMaterial needs normals; a mesh without them spawns fine and renders invisible. Programmatic meshes: .with_computed_flat_normals() (or insert ATTRIBUTE_NORMAL).
• Back-face culling is on by default — wrong winding = invisible faces.
• GLTF scenes spawn via scene labels ("model.glb#Scene0"), not the raw asset handle.
• Visibility inherits: parents without Visibility/InheritedVisibility make children invisible — common with hand-built hierarchies around loaded scenes.
• 0.18: mesh accessors became try_* returning Result<_, MeshAccessError>; MaterialPlugin fields (prepass_enabled, shadows_enabled) became Material trait methods.
• 0.19: GLTF material loading returns GltfMaterial — use the #Material0/std label for a StandardMaterial. Assets::get_mut returns mutation-tracked AssetMut<A>. Scene/SceneRoot renamed to WorldAsset/WorldAssetRoot.

Custom material shaders — bind groups

Material bindings are @group(3) (0.18+), not @group(2):

Group	Contents
0	view
1	globals/lights
2	mesh (storage buffer)
3	material (AsBindGroup)

@group(2) for material uniforms produces the confusing Storage class Storage doesn't match the shader Uniform error — group 2 is the mesh storage buffer.

Import: use bevy::shader::ShaderRef; (moved out of bevy::render::render_resource in 0.18).

Lighting

AmbientLight split (0.18):

• GlobalAmbientLight — resource, all cameras.
• AmbientLight — component on a camera entity, per-camera.

Assets

• Assets are not ready right after asset_server.load(). Gate on AssetEvent::LoadedWithDependencies or AssetServer::is_loaded_with_dependencies().
• Cache poisoning: the server dedups by path. A load_with_settings that strips data (e.g. load_meshes = RenderAssetUsages::empty()) poisons the cache; a later load() of the same path returns the stripped asset — invisible models, zero errors. Never mix stripped and rendered loads of the same path in one process; stripped loads belong to headless tools only.
• 0.18: LoadContext::path() returns AssetPath, not Path; image reinterpret_* return Result.
• 0.19: AssetPath::resolve()/resolve_embed() take &AssetPath; the string-taking variants are resolve_str()/resolve_embed_str().