Rendering Pipeline

The Rendering Pipeline manages the visual representation of game worlds, models, and UI elements. It translates original game data into modern graphics via Bevy, while maintaining fidelity to the 1998 source material's visual artifacts, such as Glide-based fog, fixed-point texture coordinates, and depth-based clipping. Sources: crates/cyrus-render/src/fog.rs:1-10, README.md

Core Architecture and Data Flow

The pipeline operates by consuming environmental requests and world data to update scene materials and geometry. It applies specialized shaders to handle legacy behaviors like terrain lighting and fog. Sources: crates/cyrus-render/src/fog.rs:163-180

The diagram shows the flow from environmental data to final mesh preparation through material extensions. Sources: crates/cyrus-render/src/fog.rs:163-190, crates/cyrus-render/src/fog/clipping.rs:114-130

Key Components

Sources: crates/cyrus-render/src/fog.rs:31-40, crates/cyrus-render/src/fog.rs:88-100

Fog and Clipping Systems

The pipeline implements faithful Glide-style fog using a 16-entry fog table and distance-based clipping. Conditions are checked before actions: if the fidelity mode is set to Modern, the pipeline extends the far clipping plane beyond the original game's limits. Sources: crates/cyrus-render/src/fog.rs:36-50, crates/cyrus-render/src/fog.rs:290-305

Depth Clipping Logic

Model draw geometry is prepared separately to preserve authored poses while clipping lit RGB values at the camera's near and far planes. The Source component tracks the draw entity and polygon metadata to perform these calculations. Sources: crates/cyrus-render/src/fog/clipping.rs:1-20

The sequence shows how the preparation system synchronizes with mesh assets and camera viewports. Sources: crates/cyrus-render/src/fog/clipping.rs:135-155

Terrain and World Rendering

Terrain rendering utilizes a grid-based admission window. The Window struct defines which vertices are active based on the camera's local position. It uses fixed-point texture coefficients and packed coefficients for RED, GREEN, and BLUE planes. Sources: crates/cyrus-render/src/terrain.rs:15-30, crates/cyrus-render/src/terrain.rs:80-95

Mesh Attributes for Specialized Rendering

The pipeline inserts custom attributes into meshes to support the unique rendering requirements of the engine:

• PROJECTED (Float32x4): Stores screen-space projected coordinates.
• RED, GREEN, BLUE (Sint32x4): Stores fixed-point lighting plane coefficients.
• TEXTURE (Uint32x4): Packed signed coefficients for nine texture-plane parameters.

Sources: crates/cyrus-render/src/terrain.rs:11-25, crates/cyrus-render/src/fog/clipping.rs:343-355

Asset Preview Rendering

The asset viewer uses a specialized camera and root entity structure to display models and spatial cells. It includes logic to frame the camera automatically around the bounds of a loaded model or spatial octree. Sources: crates/cyrus-viewer/src/preview.rs:1-25

The flow describes how assets are initialized and framed in the viewer. Sources: crates/cyrus-viewer/src/preview.rs:30-60, crates/cyrus-viewer/src/preview.rs:142-160

Shading Modes

The viewer supports several shading models via SurfaceStyle:

• Textured: Standard PBR materials.
• Unlit: Full brightness without lighting calculations.
• Solid: Flat gray color for structural inspection.
• Wireframe: Displays geometry edges only.

Sources: crates/cyrus-viewer/src/preview.rs:356-375

Implementation Details

The pipeline uses prepare_model_geometry to validate model data before rendering. It extracts chroma keying information from Gltf extras and calculates texture layout based on original BSI formats. Sources: crates/cyrus-render/src/fog.rs:388-410

// crates/cyrus-render/src/fog.rs:414-420
let [w, h] = layout.allocation_dimensions().map(u32::from);
let [x, y] = layout.sampling_stride().map(u32::from);
texture_layout = UVec4::new(w, h, x, y);
let [u, v] = layout.coordinate_scale();
texture_scale = Vec4::new(u, v, layout.sampling_level() as f32, 0.0);

The rendering pipeline serves as the bridge between extracted legacy assets and a modern hardware-accelerated presentation. It ensures that technical improvements like higher frame rates do not compromise the "Faithful" aesthetic of the original game. Sources: crates/cyrus-render/src/fog.rs:1-5, AGENTS.md