tessera_ui/renderer/
command.rs

1//! Unified command system for rendering and computation.
2//!
3//! This module defines the `Command` enum that unifies draw and compute operations
4//! into a single type, enabling seamless integration of graphics and compute pipelines
5//! in the rendering workflow.
6
7use std::any::Any;
8
9use crate::{
10    ComputeCommand, DrawCommand,
11    px::{Px, PxRect},
12};
13
14/// Defines the sampling requirements for a rendering command that needs a barrier.
15#[derive(Debug, Clone, Copy, PartialEq)]
16pub enum BarrierRequirement {
17    /// The command needs to sample from the entire previously rendered scene.
18    /// This will cause a full-screen texture copy.
19    Global,
20
21    /// The command needs to sample from a region relative to its own bounding box.
22    /// The `padding` value extends the sampling area beyond the component's own size.
23    /// For example, a `padding` of `10.0` on all sides means the component can
24    /// access pixels up to 10px outside its own boundaries.
25    PaddedLocal {
26        top: Px,
27        right: Px,
28        bottom: Px,
29        left: Px,
30    },
31
32    /// The command needs to sample from a specific, absolute region of the screen.
33    Absolute(PxRect),
34}
35
36impl BarrierRequirement {
37    pub const ZERO_PADDING_LOCAL: Self = Self::PaddedLocal {
38        top: Px::ZERO,
39        right: Px::ZERO,
40        bottom: Px::ZERO,
41        left: Px::ZERO,
42    };
43}
44
45/// Trait providing type erasure capabilities for command objects.
46///
47/// This trait allows commands to be stored and passed around as trait objects
48/// while still providing access to their concrete types when needed for
49/// pipeline dispatch.
50pub trait AsAny {
51    /// Returns a reference to the concrete type as `&dyn Any`.
52    fn as_any(&self) -> &dyn Any;
53}
54
55/// Blanket implementation of `AsAny` for all types that implement `Any`.
56impl<T: Any> AsAny for T {
57    fn as_any(&self) -> &dyn Any {
58        self
59    }
60}
61
62/// Unified command enum that can represent either a draw or compute operation.
63///
64/// This enum enables the rendering system to process both graphics and compute
65/// commands in a unified pipeline, with proper barrier handling for multi-pass
66/// rendering scenarios.
67pub enum Command {
68    /// A graphics rendering command processed by draw pipelines
69    Draw(Box<dyn DrawCommand>),
70    /// A GPU computation command processed by compute pipelines
71    Compute(Box<dyn ComputeCommand>),
72    /// A command to push a clipping rectangle onto the stack
73    ClipPush(PxRect),
74    /// A command to pop the most recent clipping rectangle from the stack
75    ClipPop,
76}
77
78impl Command {
79    /// Returns the barrier requirement for this command.
80    ///
81    /// Commands that need to sample from previously rendered content
82    /// should return a barrier requirement to ensure proper synchronization.
83    #[must_use]
84    pub fn barrier(&self) -> Option<BarrierRequirement> {
85        match self {
86            Self::Draw(command) => command.barrier(),
87            // Currently, compute can only be used for after effects,
88            Self::Compute(command) => Some(command.barrier()),
89            Self::ClipPush(_) | Self::ClipPop => None, // Clipping commands do not require barriers
90        }
91    }
92}
93
94impl Clone for Command {
95    fn clone(&self) -> Self {
96        match self {
97            Self::Draw(cmd) => Self::Draw(cmd.clone_box()),
98            Self::Compute(cmd) => Self::Compute(cmd.clone_box()),
99            Self::ClipPush(rect) => Self::ClipPush(*rect),
100            Self::ClipPop => Self::ClipPop,
101        }
102    }
103}
104
105/// Automatic conversion from boxed draw commands to unified commands
106impl From<Box<dyn DrawCommand>> for Command {
107    fn from(val: Box<dyn DrawCommand>) -> Self {
108        Self::Draw(val)
109    }
110}
111
112/// Automatic conversion from boxed compute commands to unified commands
113impl From<Box<dyn ComputeCommand>> for Command {
114    fn from(val: Box<dyn ComputeCommand>) -> Self {
115        Self::Compute(val)
116    }
117}
tessera_ui/renderer/command.rs

tessera_ui/renderer/
command.rs
