ShadowPass

ShadowPass renders the scene from the light's point of view into a depth-only framebuffer. The resulting shadow map is consumed by GeometryPass to evaluate shadow visibility per fragment.

Render Graph Role

Attribute	Value
Group	Geometry
Reads	-
Writes	shadow_map (DEPTH_ONLY framebuffer)
Cullable	Yes

Shadow Map

The shadow map is a transient DEPTH_ONLY framebuffer declared in the render graph:

uint32_t shadow_map = builder.declare_framebuffer(
    "shadow_map", 2048, 2048,
    FramebufferTextureFormat::DEPTH_ONLY
);

builder.add_pass(create_scope<ShadowPass>())
    .write(shadow_map)
    .end();

Resolution is fixed at 2048×2048 by default. Higher values reduce aliasing at the cost of memory and fill rate.

Projection

ShadowPass constructs an orthographic light-space projection matrix from the active directional light's direction and the scene's bounding volume. The resulting light_space_matrix is stored in a logical buffer and read by GeometryPass to transform fragment positions into light space.

Shadow Technique

The pass implements PCF (Percentage Closer Filtering) with a 3×3 kernel. The kernel size and bias are configurable via the pass constructor.

Limitations

• Only a single directional light shadow is supported per frame.
• Point light shadows (cubemap shadow maps) are not yet implemented.