onedrop_renderer/
pipeline_helpers.rs

1//! Small helpers shared by the renderer's overlay pipelines (waveform,
2//! custom waves, custom shapes, borders, motion vectors).
3//!
4//! Kept deliberately minimal — each pipeline still owns its own pipeline
5//! descriptor end-to-end so the bindings, vertex layout, and topology
6//! stay obvious at the call site. These helpers just remove the two
7//! pieces of literal duplication that contributed nothing to readability:
8//! the boilerplate around [`wgpu::ShaderModuleDescriptor`] and the
9//! additive-vs-alpha blend-state switch.
10
11/// Compile an inline WGSL source string into a [`wgpu::ShaderModule`]
12/// with the supplied label.
13///
14/// The source is taken as `'static` to encourage call sites to pass
15/// `include_str!("../shaders/<name>.wgsl")` (the dominant pattern) rather
16/// than building a string at runtime.
17pub(crate) fn load_wgsl(
18    device: &wgpu::Device,
19    label: &str,
20    source: &'static str,
21) -> wgpu::ShaderModule {
22    device.create_shader_module(wgpu::ShaderModuleDescriptor {
23        label: Some(label),
24        source: wgpu::ShaderSource::Wgsl(source.into()),
25    })
26}
27
28/// Standard MD2-style blend state for an overlay pipeline.
29///
30/// - `additive = false` → straight alpha blending (preset opacity composes
31///   over the warp output).
32/// - `additive = true` → MD2's additive mode where `src.rgb * src.alpha`
33///   is added on top of the destination. Used by `b_additive_waves`,
34///   `b_additive` (custom waves), and the additive variant of the
35///   custom-shape pipeline.
36pub(crate) fn blend_state_for(additive: bool) -> wgpu::BlendState {
37    if additive {
38        wgpu::BlendState {
39            color: wgpu::BlendComponent {
40                src_factor: wgpu::BlendFactor::SrcAlpha,
41                dst_factor: wgpu::BlendFactor::One,
42                operation: wgpu::BlendOperation::Add,
43            },
44            alpha: wgpu::BlendComponent {
45                src_factor: wgpu::BlendFactor::One,
46                dst_factor: wgpu::BlendFactor::One,
47                operation: wgpu::BlendOperation::Add,
48            },
49        }
50    } else {
51        wgpu::BlendState::ALPHA_BLENDING
52    }
53}
onedrop_renderer/pipeline_helpers.rs

onedrop_renderer/
pipeline_helpers.rs
