The Default Pipeline

The engine constructs a default render graph with all built-in passes. This chapter shows the complete pass ordering and data flow.

Pass Execution Order

The graph topologically sorts these passes based on their dependencies. The typical execution order is:

1.  ClearPass           - Clear scene_color and depth
2.  ShadowDepthPass     - Render cascaded shadow maps + spotlight shadows
3.  SkyPass             - Render procedural atmosphere to scene_color
4.  ScenePass           - Render scene objects (simple path) to scene_color
5.  MeshPass            - Render PBR meshes with shadows and lighting
6.  SkinnedMeshPass     - Render animated skeletal meshes
7.  WaterPass           - Render water surface
8.  WaterMeshPass       - Render water mesh displacement
9.  GrassPass           - Render GPU-instanced grass
10. GridPass            - Render infinite ground grid
11. LinesPass           - Render debug lines
12. SelectionMaskPass   - Generate selection mask for editor
13. OutlinePass         - Render selection outline

    --- User passes (from configure_render_graph) ---

14. BloomPass           - HDR bloom (default)
15. PostProcessPass     - Tonemapping and compositing (default)
16. BlitPass            - Copy to swapchain (default)

    --- UI passes ---

17. EguiPass            - egui UI (if egui feature enabled)

Data Flow Diagram

                    shadow_depth
ShadowDepthPass --> spotlight_shadow_atlas
                        |
                        v
SkyPass ----------> scene_color <-- ClearPass
                        |
MeshPass ----------> scene_color, depth, entity_id, view_normals
                        |
SkinnedMeshPass --> scene_color, depth
                        |
WaterPass --------> scene_color, depth
GrassPass --------> scene_color, depth
GridPass ---------> scene_color, depth
LinesPass --------> scene_color, depth
                        |
                        v
BloomPass --------> bloom (half-res)
                        |
PostProcessPass --> compute_output
    reads: scene_color, bloom, ssao
                        |
BlitPass ---------> swapchain

Core Passes (Always Present)

These passes are added by the engine during renderer initialization. They cannot be removed, but can be disabled at runtime.

ClearPass

Clears scene_color to black and depth to 0.0 (reversed-Z far plane).

SkyPass

Renders the procedural atmosphere or solid background color. Controlled by world.resources.graphics.atmosphere.

ScenePass

A simple scene rendering pass for basic objects.

ShadowDepthPass

Renders the shadow map. See Shadow Mapping.

MeshPass

The main PBR mesh rendering pass. See Geometry Passes.

SkinnedMeshPass

Renders animated skeletal meshes with GPU skinning.

Selection Passes

SelectionMaskPass and OutlinePass generate and render editor selection outlines.

User-Configurable Passes (Default)

These passes are added by the default configure_render_graph() implementation. Override this method to replace them.

BloomPass

Reads scene_color, writes a half-resolution bloom texture.

PostProcessPass

Reads scene_color, bloom, and ssao. Performs tonemapping and compositing. Writes to compute_output.

BlitPass

Copies compute_output to swapchain for presentation.

The default pipeline only includes bloom and tonemapping. To enable SSAO, SSGI, or SSR, override configure_render_graph() and add the appropriate passes. See Post-Processing for the full list of available post-processing passes and Custom Passes for examples.

Nightshade Game Engine