make every bevy dependency optional in bevy crate

Cargo.toml

@@ -5,24 +5,37 @@ authors = ["Carter Anderson <mcanders1@gmail.com>"]
 edition = "2018"
 
 [features]
-default = ["bevy_wgpu", "bevy_winit"]
+default = ["headless", "wgpu", "winit"]
+headless = ["asset", "core", "derive", "diagnostic", "input", "render", "serialization", "transform", "ui", "window"]
+asset = ["bevy_asset"]
+core = ["bevy_core"]
+derive = ["bevy_derive"]
+diagnostic = ["bevy_diagnostic"]
+input = ["bevy_input"]
+render = ["bevy_render"]
+serialization = ["bevy_serialization"]
+transform = ["bevy_transform"]
+ui = ["bevy_ui"]
+window = ["bevy_window"]
+wgpu = ["bevy_wgpu"]
+winit = ["bevy_winit"]
 
 [dependencies]
 # bevy
 bevy_app = { path = "bevy_app" }
-bevy_asset = { path = "bevy_asset" }
-bevy_core = { path = "bevy_core" }
-bevy_derive = { path = "bevy_derive" }
-bevy_diagnostic = { path = "bevy_diagnostic" }
-bevy_input = { path = "bevy_input" }
-bevy_render = { path = "bevy_render" }
-bevy_serialization = { path = "bevy_serialization" }
-bevy_transform = { path = "bevy_transform" }
-bevy_ui = { path = "bevy_ui" }
-bevy_window = { path = "bevy_window" }
+bevy_asset = { path = "bevy_asset", optional = true }
+bevy_core = { path = "bevy_core", optional = true }
+bevy_derive = { path = "bevy_derive", optional = true }
+bevy_diagnostic = { path = "bevy_diagnostic", optional = true }
+bevy_input = { path = "bevy_input", optional = true }
+bevy_render = { path = "bevy_render", optional = true }
+bevy_serialization = { path = "bevy_serialization", optional = true }
+bevy_transform = { path = "bevy_transform", optional = true }
+bevy_ui = { path = "bevy_ui", optional = true }
+bevy_window = { path = "bevy_window", optional = true }
 bevy_wgpu = { path = "bevy_wgpu", optional = true }
 bevy_winit = { path = "bevy_winit", optional = true }
-legion = { path = "bevy_legion", features = ["serialize"] }
+legion = { path = "bevy_legion" }
 
 # other
 log = { version = "0.4", features = ["release_max_level_info"] }

bevy_ui/src/ui_update_system.rs

@@ -12,16 +12,17 @@ pub fn ui_update_system() -> Box<dyn Schedulable> {
         .write_component::<Node>()
         .read_component::<Children>()
         .build(move |_, world, windows, node_query| {
-            let window = windows.get_primary().unwrap();
-            let parent_size = glam::vec2(window.width as f32, window.height as f32);
-            let parent_position = glam::vec2(0.0, 0.0);
-            for (entity, _) in node_query.iter_entities_mut(world) {
-                run_on_hierarchy_subworld_mut(
-                    world,
-                    entity,
-                    (parent_size, parent_position),
-                    &mut update_node_entity,
-                );
+            if let Some(window) = windows.get_primary() {
+                let parent_size = glam::vec2(window.width as f32, window.height as f32);
+                let parent_position = glam::vec2(0.0, 0.0);
+                for (entity, _) in node_query.iter_entities_mut(world) {
+                    run_on_hierarchy_subworld_mut(
+                        world,
+                        entity,
+                        (parent_size, parent_position),
+                        &mut update_node_entity,
+                    );
+                }
             }
         })
 }

examples/headless.rs

@@ -4,6 +4,13 @@ use bevy::{
 };
 use std::time::Duration;
 
+// This example disables the default plugins by not registering them during setup.
+// You can also completely remove rendering / windowing Plugin code from bevy
+// by making your import look like this in your Cargo.toml
+//
+// [dependencies]
+// bevy = { version = "0.1.0", default-features = false, features = ["headless"] }
+
 fn main() {
     println!("This app runs once:");
     App::build()

examples/scene.rs

@@ -27,23 +27,13 @@ fn setup(world: &mut World, resources: &mut Resources) {
         .add_entity(MeshEntity {
             mesh: plane_handle,
             material: plane_material_handle,
-            // renderable: Renderable::instanced(),
             ..Default::default()
         })
         // cube
         .add_entity(MeshEntity {
             mesh: cube_handle,
             material: cube_material_handle,
-            // renderable: Renderable::instanced(),
-            translation: Translation::new(-1.5, 0.0, 1.0),
-            ..Default::default()
-        })
-        // cube
-        .add_entity(MeshEntity {
-            mesh: cube_handle,
-            material: cube_material_handle,
-            // renderable: Renderable::instanced(),
-            translation: Translation::new(1.5, 0.0, 1.0),
+            translation: Translation::new(0.0, 0.0, 1.0),
             ..Default::default()
         })
         // light

src/lib.rs

@@ -2,19 +2,30 @@
 pub mod prelude;
 
 pub use bevy_app as app;
-pub use bevy_asset as asset;
-pub use bevy_core as core;
-pub use bevy_diagnostic as diagnostic;
-pub use bevy_input as input;
-pub use bevy_render as render;
-pub use bevy_serialization as serialization;
-pub use bevy_transform as transform;
-pub use bevy_ui as ui;
-pub use bevy_window as window;
-
 pub use glam as math;
 pub use legion;
 
+#[cfg(feature = "asset")]
+pub use bevy_asset as asset;
+#[cfg(feature = "core")]
+pub use bevy_core as core;
+#[cfg(feature = "derive")]
+pub use bevy_derive as derive;
+#[cfg(feature = "diagnostic")]
+pub use bevy_diagnostic as diagnostic;
+#[cfg(feature = "input")]
+pub use bevy_input as input;
+#[cfg(feature = "render")]
+pub use bevy_render as render;
+#[cfg(feature = "serialization")]
+pub use bevy_serialization as serialization;
+#[cfg(feature = "transform")]
+pub use bevy_transform as transform;
+#[cfg(feature = "ui")]
+pub use bevy_ui as ui;
+#[cfg(feature = "window")]
+pub use bevy_window as window;
+
 use app::AppBuilder;
 
 pub trait AddDefaultPlugins {
@@ -23,25 +34,28 @@ pub trait AddDefaultPlugins {
 
 impl AddDefaultPlugins for AppBuilder {
     fn add_default_plugins(&mut self) -> &mut Self {
-        self.add_plugin(bevy_core::CorePlugin::default())
-            .add_plugin(bevy_input::InputPlugin::default())
-            .add_plugin(bevy_window::WindowPlugin::default())
-            .add_plugin(bevy_render::RenderPlugin::default())
-            .add_plugin(ui::UiPlugin::default());
+        #[cfg(feature = "core")]
+        self.add_plugin(bevy_core::CorePlugin::default());
 
-        #[cfg(feature = "bevy_winit")]
-        {
-            self.add_plugin(bevy_winit::WinitPlugin::default());
-        }
-        #[cfg(not(feature = "bevy_winit"))]
-        {
-            self.add_plugin(bevy_app::schedule_run::ScheduleRunner::default());
-        }
+        #[cfg(feature = "input")]
+        self.add_plugin(bevy_input::InputPlugin::default());
 
-        #[cfg(feature = "bevy_wgpu")]
-        {
-            self.add_plugin(bevy_wgpu::WgpuRendererPlugin::default());
-        }
+        #[cfg(feature = "window")]
+        self.add_plugin(bevy_window::WindowPlugin::default());
+
+        #[cfg(feature = "render")]
+        self.add_plugin(bevy_render::RenderPlugin::default());
+
+        #[cfg(feature = "ui")]
+        self.add_plugin(ui::UiPlugin::default());
+
+        #[cfg(feature = "winit")]
+        self.add_plugin(bevy_winit::WinitPlugin::default());
+        #[cfg(not(feature = "winit"))]
+        self.add_plugin(bevy_app::schedule_runner::ScheduleRunnerPlugin::default());
+
+        #[cfg(feature = "wgpu")]
+        self.add_plugin(bevy_wgpu::WgpuRendererPlugin::default());
 
         self
     }

src/prelude.rs

@@ -1,30 +1,18 @@
-pub use crate::{
-    app::{App, AppBuilder, AppPlugin, EntityArchetype, EventReader, Events, GetEventReader},
-    asset::{Asset, AssetStorage, Handle},
-    core::{
-        time::Time,
-        transform::{CommandBufferBuilderSource, WorldBuilder, WorldBuilderSource},
-    },
-    diagnostic::DiagnosticsPlugin,
-    render::{
-        entity::*,
-        mesh::{Mesh, MeshType},
-        pipeline::PipelineDescriptor,
-        render_graph::RenderGraph,
-        render_resource::{
-            resource_name, resource_providers::UniformResourceProvider, AssetBatchers,
-        },
-        shader::{uniforms::StandardMaterial, Shader, ShaderDefSuffixProvider, ShaderStage},
-        texture::{Texture, TextureType},
-        ActiveCamera, ActiveCamera2d, Camera, CameraType, Color, ColorSource, Light, Renderable,
-    },
-    ui::{entity::*, Anchors, Margins, Node},
-    window::{Window, WindowDescriptor, WindowPlugin, Windows},
-    AddDefaultPlugins,
+pub use crate::AddDefaultPlugins;
+pub use crate::app::{App, AppBuilder, AppPlugin, EntityArchetype, EventReader, Events, GetEventReader};
+#[cfg(feature = "asset")]
+pub use crate::asset::{Asset, AssetStorage, Handle};
+#[cfg(feature = "derive")]
+pub use crate::derive::*;
+#[cfg(feature = "transform")]
+pub use crate::transform::prelude::*;
+#[cfg(feature = "core")]
+pub use crate::core::{
+    time::Time,
+    transform::{CommandBufferBuilderSource, WorldBuilder, WorldBuilderSource},
 };
-pub use bevy_derive::*;
-pub use bevy_transform::prelude::*;
-pub use glam as math;
+#[cfg(feature = "diagnostic")]
+pub use crate::diagnostic::DiagnosticsPlugin;
 pub use legion::{
     command::CommandBuffer,
     entity::Entity,
@@ -39,4 +27,19 @@ pub use legion::{
     },
     world::{Universe, World},
 };
-pub use math::{Mat3, Mat4, Quat, Vec2, Vec3, Vec4};
+pub use crate::math::{self, Mat3, Mat4, Quat, Vec2, Vec3, Vec4};
+#[cfg(feature = "render")]
+pub use crate::render::{
+    entity::*,
+    mesh::{Mesh, MeshType},
+    pipeline::PipelineDescriptor,
+    render_graph::RenderGraph,
+    render_resource::{resource_name, resource_providers::UniformResourceProvider, AssetBatchers},
+    shader::{uniforms::StandardMaterial, Shader, ShaderDefSuffixProvider, ShaderStage},
+    texture::{Texture, TextureType},
+    ActiveCamera, ActiveCamera2d, Camera, CameraType, Color, ColorSource, Light, Renderable,
+};
+#[cfg(feature = "ui")]
+pub use crate::ui::{entity::*, Anchors, Margins, Node};
+#[cfg(feature = "window")]
+pub use crate::window::{Window, WindowDescriptor, WindowPlugin, Windows};