Module bevy_render::render_phase

The modular rendering abstraction responsible for queuing, preparing, sorting and drawing entities as part of separate render phases.

In Bevy each view (camera, or shadow-casting light, etc.) has one or multiple RenderPhases (e.g. opaque, transparent, shadow, etc). They are used to queue entities for rendering. Multiple phases might be required due to different sorting/batching behaviors (e.g. opaque: front to back, transparent: back to front) or because one phase depends on the rendered texture of the previous phase (e.g. for screen-space reflections).

To draw an entity, a corresponding PhaseItem has to be added to one or multiple of these render phases for each view that it is visible in. This must be done in the RenderSet::Queue. After that the render phase sorts them in the RenderSet::PhaseSort. Finally the items are rendered using a single TrackedRenderPass, during the RenderSet::Render.

Therefore each phase item is assigned a Draw function. These set up the state of the TrackedRenderPass (i.e. select the RenderPipeline, configure the BindGroups, etc.) and then issue a draw call, for the corresponding item.

The Draw function trait can either be implemented directly or such a function can be created by composing multiple RenderCommands.

Structs

• DrawFunctionId
  An identifier for a Draw function stored in DrawFunctions.
• DrawFunctions
  Stores all draw functions for the PhaseItem type hidden behind a reader-writer lock.
• DrawFunctionsInternal
  Stores all Draw functions for the PhaseItem type.
• RenderCommandState
  Wraps a RenderCommand into a state so that it can be used as a Draw function.
• RenderPhase
  A collection of all rendering instructions, that will be executed by the GPU, for a single render phase for a single view.
• SetItemPipeline
  A RenderCommand that sets the pipeline for the CachedRenderPipelinePhaseItem.
• TrackedRenderPass
  A RenderPass, which tracks the current pipeline state to skip redundant operations.
• ViewRangefinder3d
  A distance calculator for the draw order of PhaseItems.

Enums

• RenderCommandResult
  The result of a RenderCommand.

Traits

• AddRenderCommand
  Registers a RenderCommand as a Draw function. They are stored inside the DrawFunctions resource of the app.
• CachedRenderPipelinePhaseItem
  A PhaseItem item, that automatically sets the appropriate render pipeline, cached in the PipelineCache.
• Draw
  A draw function used to draw PhaseItems.
• PhaseItem
  An item (entity of the render world) which will be drawn to a texture or the screen, as part of a RenderPhase.
• RenderCommand
  RenderCommands are modular standardized pieces of render logic that can be composed into Draw functions.

Functions

• sort_phase_system
  This system sorts the PhaseItems of all RenderPhases of this type.