PostProcessPass

PostProcessPass is the final image-space pass. It reads the composited scene_color attachment and applies a chain of full-screen subpasses - HDR tone mapping, bloom, FXAA, and vignette - before writing to the output framebuffer presented to the window.

Render Graph Role

Attribute	Value
Group	VFX
Reads	scene_color, mesh_context, mesh_collector_storage
Writes	output (window framebuffer)
Cullable	Yes

Subpasses

Subpasses run sequentially as ping-pong blit operations over internal transient textures. Each subpass can be toggled independently.

HDR Tone Mapping

Converts the linear HDR scene_color (RGBA16F) to LDR for display using the ACES filmic tone curve. Exposure is controlled by a scalar uniform.

Bloom

A two-pass bloom: a threshold extract followed by a dual Kawase blur. The blurred result is additively blended back onto the tone-mapped image. Configurable threshold and intensity.

FXAA

Fast Approximate Anti-Aliasing runs on the LDR image after tone mapping. It detects edges via luminance contrast and blends neighbour samples to smooth them.

Vignette

Applies a radial darkening from the center outward. Radius and strength are configurable.

Configuration

Subpasses are configured on the pass before the graph is compiled:

auto pp = create_scope<PostProcessPass>();
pp->hdr.exposure      = 1.2f;
pp->bloom.threshold   = 0.8f;
pp->bloom.intensity   = 0.4f;
pp->bloom.enabled     = true;
pp->fxaa.enabled      = true;
pp->vignette.strength = 0.35f;
pp->vignette.enabled  = true;

builder.add_pass(std::move(pp))
    .read(scene_color)
    .write(output)
    .end();

Custom Effects

Additional image-space effects can be injected by subclassing PostProcessSubpass and registering it with the pass:

pp->add_subpass(create_scope<MyCustomEffect>());

Custom subpasses run after the built-in chain in registration order.