UeShadowMapViewer

UeShadowMapViewer is a debug utility that renders a visual representation of a light's shadow map on the screen. This is useful for debugging shadow mapping issues, verifying shadow quality, and understanding how shadows are being rendered.

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Constructor

new UeShadowMapViewer(light, data = {})

Parameters

Parameter	Type	Default	Description
light	UeLight	required	The light whose shadow map to display
data	struct	{}	Configuration object for viewer properties

Data Properties

Property	Type	Default	Description
enabled	boolean	true	Whether the viewer is currently active
width	number	256	Display width in pixels
height	number	256	Display height in pixels

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Properties

Property	Type	Default	Description
light	UeLight	-	Reference to the light being visualized
enabled	boolean	true	Whether to render the viewer
width	number	256	Width of the rendered shadow map preview
height	number	256	Height of the rendered shadow map preview

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Methods

render(camera, x1, y1)

Renders the shadow map preview at the specified screen coordinates.

This method should be called after the main scene rendering, typically in a draw event.

Parameters:

• camera (UeCamera) - The main scene camera (not currently used)
• x1 (number) - X coordinate on screen where to draw the preview
• y1 (number) - Y coordinate on screen where to draw the preview

Returns: Nothing

Behavior:

• Returns early if viewer is disabled or light/shadow map is invalid
• Checks if the shadow map surface exists
• Scales the shadow map to fit the viewer's width/height
• Draws the surface at the specified position

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Usage Example

// Create a directional light with shadows
const dirLight = new UeDirectionalLight(c_white, 1.5);
dirLight.position.set(100, 200, 150);
dirLight.castShadow = true;
dirLight.shadow.updateMapSize(1024, 1024);
scene.add(dirLight);

// Create a shadow map viewer
const shadowViewer = new UeShadowMapViewer(dirLight, {
    width: 256,
    height: 256,
    enabled: true
});

// In your draw event:
shadowViewer.render(camera, 10, 10); // Top-left corner

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Debug Workflow

The shadow map viewer is particularly useful for:

1. Verifying shadow coverage - Check if your shadow camera frustum properly covers the scene
2. Diagnosing shadow artifacts - Inspect depth values to identify acne, peter-panning, or precision issues
3. Optimizing shadow resolution - Compare different shadow map sizes visually
4. Understanding depth distribution - See how depth values are distributed across the map

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Notes

• The shadow map is stored in r32float format (32-bit floating-point depth values)
• White pixels represent maximum depth (far plane), darker pixels represent closer geometry
• The viewer automatically scales the shadow map surface to fit the specified display size
• Disabling the viewer (enabled = false) prevents rendering without destroying the viewer object
• For point lights with cube shadow maps, you would need 6 separate viewers (one per face) - currently only single-face shadow maps are supported