Planar Shadows

Overview

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

• Supports batching with extremely low shader cost, suitable for mobile platforms.

• Even if expensive ShadowMap technology is desired for shadow effects, this solution can be used in low-quality settings so that low-end configurations can still have shadows.

Key Features

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

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

• Supports stylization — customize shadow styles using textures.

• Supports configurable shadow color and transparency.

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

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

• Supports SRP Batcher — SRP-compatible batching.

Supported Shadow Types

• StaticHeightShadow

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

• OriginHeightShadow

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

• RootHeightShadow

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

• RaycastGroundShadow

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

Usage

• Use "Tools/GraphicsCat/Graphics/PlanarShadows Setup" menu to automatically set up planar shadows.

• The auto-setup tool will:

  • Add PlanarShadowsRendererFeature to the Renderer used by the main camera.

  • Create a GlobalVolume in the scene and add PlanarShadowsVolume to it.

• If the menu tool fails to set up correctly, please set it up manually.

• Configure PlanarShadowsVolume parameters.

• Add the RootHeightShadow component to composite objects.

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

Parameter Reference

• 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.

• OriginHeightShadow 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 OriginHeightShadow 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.

Shadows Not Visible in SceneView

• SceneView uses the default Renderer, so you must also add PlanarShadowsRendererFeature to the default Renderer to see shadows in SceneView.

• The auto-setup menu already does this for you; if not, please add it manually.

Enjoying this package?

• Give it a quick rating or leave a short review on the Unity Asset Store.

• Your feedback helps us improve and add even more features!

• Review on Unity Asset Store