Planar Shadows v1.3.0

Overview

  • This solution implements planar shadows based on the URP framework.

  • Clean and lightweight, with minimal performance cost, suitable for mobile platforms.

Use Cases

  • Ideal for flat-ground environments, where planar shadows deliver strong visual results.

  • Well-suited for character showcase scenes, with gradients and stylization enhancing visual fidelity.

  • Useful for performance scaling: apply high-cost shadows on high-end devices, and PlanarShadows on low-end ones.

Shadow Types

  • Static Height Shadow

    • Renders all shadows at a fixed height, suitable for objects on the same horizontal plane.

  • Origin Height Shadow

    • Renders shadows at the model’s origin position, suitable for objects placed at different heights.

  • Root Height Shadow

    • Renders shadows at the root position of a composite object, suitable for complex objects at varying heights.

  • Raycast Ground Shadow

    • Detects ground height via raycast and renders shadows on the ground, suitable for characters jumping between platforms.

Visual Features

  • Supports configurable shadow color and transparency.

  • Supports non-stacking shadows — shadows will not overlap each other (fade gradient not supported in this mode).

  • Supports fade gradient — the farther the shadow is from the origin, the lighter its color becomes.

  • Supports stylization — customize shadow styles using textures.

Feature Support

  • Supports complex objects (multiple parts, multiple submeshes).

  • Supports Volume — configure via Volume to suit different scene requirements.

Performance Advantages

  • Extremely low overhead, with most calculations handled in the vertex shader.

  • Supports SRP Batcher — SRP-compatible batching.

Deployment Instructions

  • Inspect the PlanarShadows prefab.

  • Under normal circumstances, it references a PlanarShadowMaterial.

  • If this property is empty, drag and drop PlanarShadows/Materials/PlanarShadowDefault.mat onto it.

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  • Add the PlanarShadows prefab to your scene.

  • Create a Volume and attach PlanarShadows.

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  • Configure PlanarShadowsVolume parameters.

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Basic Settings

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  • Adjust the Base parameters of the PlanarShadowsVolume.

  • ShadowColor — Sets the shadow’s color and transparency.

  • Shadow Offset — Adjusts the shadow’s height offset.

    • Used to address Z-fighting issues.

    • Also resolves cases where shadows are incorrectly occluded by the ground.

Gradient Effect Configuration

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  • Distance defines the distance from the shadow pixel to the shadow’s origin, in meters.

  • The farther from the origin, the lighter the shadow becomes, fading to fully invisible at the specified Distance.

Stylization Effect Configuration

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  • Texture

    • Defines the stylization pattern; you can apply a texture with a regular decorative pattern.

    • Ensure the texture’s Wrap Mode is set to Repeat to allow the pattern to tile seamlessly.

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  • Scale — Adjusts the pattern size; smaller values make the pattern denser.

  • Flow Speed — Controls the movement speed of the pattern.

Static Height Shadows

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  • Static Height Shadows render object shadows at a fixed height, supporting batching for multiple objects.

  • Caster — Set a LayerMask to specify which layers’ objects should cast Static Height Shadows.

  • Height — Sets the shadow height; shadows of relevant objects will be rendered at this uniform height.

Static Height Shadows Configuration

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  • Origin Height Shadows render shadows at the model’s origin height, supporting batching for multiple objects.

  • Caster — Set a LayerMask to specify which layers’ objects should cast Origin Height Shadows.

Root Height Shadows Configuration

  • Root Height Shadows render shadows at the root node of the composite object.

  • Add the RootHeightShadow component to the root of composite objects.

Raycast Ground Shadows Configuration

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  • Raycast Ground Shadows use physics raycasting to detect the ground platform’s position and render the object’s shadow there.

  • Receiver — Set a LayerMask to specify which ground platforms should receive Raycast Ground Shadows.

  • Add the RaycastGroundShadow component to objects that move or jump between platforms.

Planar Shadows Volume Parameter ReferenceBase

  • Base

    • Shadow Color — Shadow color, supports both color and transparency adjustment.

    • Shadow Offset — Height offset for shadows, fine-tune to prevent Z-fighting between shadows and ground.

  • Distance Fade

    • Distance — The distance from the object’s origin at which the shadow fades to nearly invisible.

  • Stylized

    • Texture — Stylized texture, the image content defines the stylized pattern.

    • Scale — Display size of the stylized texture; smaller values result in denser patterns.

    • Flow Speed — Scrolling speed of the stylized effect.

  • StaticHeightShadow

    • Caster — Assign objects that use StaticHeightShadow.

    • Height — The shadow rendering height for StaticHeightShadow.

  • OriginHeightShadow

    • Caster — Assign objects that use OriginHeightShadow.

  • RaycastGroundShadow

    • Receiver — Define which ground layers RaycastGroundShadow will render on.

Performance Recommendations

  • Prefer StaticHeightShadow and OriginHeightShadow for batching support.

  • RootHeightShadow does not support batching — only use for complex objects at different heights.

  • RaycastGroundShadow does not support batching — only use for characters jumping between platforms.

  • Merge meshes where possible to reduce draw calls for RootHeightShadow and RaycastGroundShadow.

OriginHeightShadow Model Requirements

  • OriginHeightShadow renders shadows at the model’s origin.

  • For static models, the bottom of the visible model should align with the origin (this is usually the case in modeling).

  • For animated models:

    • The origin is usually not at the visual bottom, so avoid using OriginHeightShadow

    • Use RootHeightShadow or RaycastGroundShadow instead

Limitations

  • Shadows are rendered horizontally, so this method is not suitable for sloped surfaces.

  • If the object is outside the camera view, its shadow will also not be visible, even if the shadow itself is within view.

  • In the Editor, if the mouse hovers over the Material Inspector, Raycast shadows may flicker.

  • Transparent materials and cutout materials are not supported for shadow rendering:

    • The transparent areas are usually customized and cannot produce accurate shadow shapes.

    • Due to inconsistent cutout implementations across materials, accurate cutout shadows cannot be guaranteed.

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