Module runtime 

Scene runtime: per-frame orchestration, plugin system, and physics hooks. Scene runtime: per-frame orchestration layer between Scene and ViewportRenderer.

ViewportRuntime runs registered plugins in a defined priority order each frame, drives a fixed timestep accumulator for physics, and flushes accumulated transform writes back to the scene. It does not own the scene, selection, or GPU resources.

Usage

use viewport_lib::runtime::{
    FixedTimestep, RuntimeFrameContext, RuntimePhase, RuntimePlugin,
    RuntimeStepContext, SceneRuntimeMode, ViewportRuntime,
};

// Build the runtime once at startup.
let mut runtime = ViewportRuntime::new()
    .with_mode(SceneRuntimeMode::Simulation)
    .with_fixed_timestep(FixedTimestep::new(60.0))
    .with_plugin(MyPhysicsPlugin::new());

// Each frame:
let mut frame_ctx = RuntimeFrameContext::default();
frame_ctx.dt = wall_dt;
frame_ctx.camera = camera.clone();
frame_ctx.viewport_size = glam::Vec2::new(width, height);
frame_ctx.input = action_frame.clone();
let output = runtime.step(&mut scene, &mut selection, &frame_ctx);

// Handle contact events in game logic:
for event in output.events.read::<viewport_lib::plugins::physics_lite::ContactEvent>() { /* ... */ }

// Render with interpolated transforms between fixed steps:
let alpha = runtime.alpha();
if let Some(t) = runtime.snapshots().interpolated(node_id, alpha) {
    // use t instead of the node's scene transform
}

Existing prepare / paint_to call sites need no changes. ViewportRuntime is purely additive and does not affect ViewportRenderer.

Re-exports

pub use camera_follow::CameraFollow;

pub use context::RuntimeFrameContext;

pub use context::RuntimeStepContext;

pub use context::SimulationStepContext;

pub use debug_draw::DebugDraw;

pub use debug_draw::DebugLayer;

pub use debug_draw::DebugPrim;

pub use events::RuntimeEventBus;

pub use gpu_plugin::GpuFrameContext;

pub use gpu_plugin::GpuPlugin;

pub use gpu_plugin::PostPaintTargets;

pub use gpu_plugin::gpu_phase;

pub use jobs::JobPoll;

pub use jobs::JobSender;

pub use jobs::JobSlot;

pub use mode::SceneRuntimeMode;

pub use output::CameraCommand;

pub use output::CameraFollowTarget;

pub use output::NodeTransformOp;

pub use output::RuntimeOutput;

pub use output::SelectionOp;

pub use output::TransformWriteback;

pub use output::apply_camera_commands;

pub use plugin::RuntimeEvent;

pub use plugin::RuntimePhase;

pub use plugin::RuntimePlugin;

pub use plugin::phase;

pub use resources::RuntimeResources;

pub use snapshot::TransformSnapshot;

pub use snapshot::TransformSnapshotTable;

pub use systems::ManipulationSystem;

pub use systems::SelectionSystem;

pub use timestep::FixedStepIter;

pub use timestep::FixedTimestep;

Modules

camera_follow

Camera tracking binding for follow-camera behavior.

context

Per-frame and per-step context types for runtime plugins.

debug_draw

Debug draw accumulator for runtime plugins. Debug draw accumulator for runtime plugins.

events

Generic typed event bus for runtime plugin communication.

gpu_plugin

GPU plugin trait and lifecycle hooks. GPU plugin trait and lifecycle hooks for runtime extensions.

guide

Plugin authoring guide. Plugin authoring guide.

jobs

Async job handoff types for runtime plugins. Async job handoff types for runtime plugins.

mode

Runtime mode enum for super::ViewportRuntime.

output

Runtime output types: transform ops, selection ops, contact events, and generic events.

plugin

Runtime plugin trait and phase ordering.

resources

Built-in animation, constraint, and physics plugins. Typed resource registry for sharing engine-owned state across runtime plugins.

snapshot

Transform snapshot table for smooth physics-driven rendering.

systems

Built-in interaction systems: SelectionSystem and ManipulationSystem.

timestep

Fixed timestep accumulator for physics and simulation.

Structs

RuntimeStats

Per-plugin timing for one runtime cycle, in milliseconds.

ViewportRuntime

Per-frame scene orchestration layer.