PunctualShadowRenderer

Remarks

The same idea as ShadowMapRenderer — a shadow map is a view, and an atlas is one pass with a viewport per tile — applied to lights that have a position. What differs is that nothing has to be fitted or stabilised: a spot light's shadow frustum is its cone and a point light's is six of them, so the whole projection question that cascades spend two hundred lines on does not arise.

A point light is six tiles and a spot light is one. That ratio is the real cost of the two and it is worth seeing: six times the culling, six times the draws, six times the atlas. It is also why the atlas is allocated in tile units rather than per light — the alternative reserves a cube's worth of space for every light in case it turns out to be one.

When the atlas runs out, lights are dropped and counted. Not silently: DroppedLights is what turns "some shadows disappeared in the big fight" into a number a profiler can show. Dropping the ones furthest down the list is arbitrary and deliberate — importance ordering belongs to whoever fills the list, which is the only place that knows what the scene is about.

Fields and properties (20)

• public required RenderStage CasterStage

  The stage that draws depth-only casters.

• public string Atlas

  The name of the atlas to render into.

• public IList<RenderLight> Lights

  The lights to shadow. Directional lights are skipped — they are the cascades'.

• public ViewConstants? Constants

  The per-view block to bind before each tile's casters.

• public ParameterCollection? Scene

  Where to publish what a shading pass needs to read the atlas, or null to publish nothing.

• public string ShaderName

  The compose-slot prefix the tile bindings are written under.

• public IList<string> Passes

  Any further prefixes the same atlas is published under.

• public IGraphicsDevice? Device

  Where the tile buffer lives. Without one, nothing is uploaded and nothing published.

• public SamplerCache? Samplers

  Where the atlas's sampler comes from. Without one, no sampler is published.

• public float ConstantBias

  How far the depth comparison is nudged, in depth units.

• public float SlopeBias

  How much more of that a surface gets as it turns away from the light.

• public int Resolution

  One tile's side in texels.

• public int TilesPerSide

  How many tiles the atlas is across, so it holds this squared.

• public float NearPlane

  The near plane every punctual shadow projection uses.

• public IReadOnlyList<ShadowTile> Tiles

  The tiles this frame allocated.

• public int TileBase

  Which record of the tile buffer this frame's tiles start at.

• public IReadOnlyList<RenderView> Views

  The views the tiles are drawn from.

• public int DroppedLights

  How many lights did not fit in the atlas this frame.

• public int Capacity

  How many tiles the atlas holds.

• public Int2 AtlasSize

  The atlas's size in texels, for whoever creates the texture.

Methods (4)

• protected internal override void Collect(GraphicsCompositor compositor)

  Declares the views and stages this node needs, before anything is culled.

• protected internal override void Build(GraphicsCompositor compositor, CompositorFrame frame)

  Declares this node's render-graph passes.

• public void Dispose()

  Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

• public override string ToString()

  Returns a string that represents the current object.

Used by (3)

• CompositorBuilderVixen.Rendering
• HarnessVixen.Rendering.Tests
• PunctualShadowTestsVixen.Rendering.Tests