SoShadowMapping

InventorModule

author	MeVis Medical Solutions AG
package	MeVisLab/Standard
dll	SoShadowMapping
definition	SoShadowMapping.def
see also	SoShadowCast
keywords	cascaded, hardware, soft, PCF, percentage, closer, depth, perception

Purpose

The SoShadowMapping renders the scene that is located below itself using Cascaded Shadow Mapping. The module renders shadows for a single directional light source.

It is based on the NVidia SDK sample at http://developer.download.nvidia.com/SDK/10/opengl/samples.html#cascaded_shadow_maps and has been ported to work inside Open Inventor.

Example screenshot:

Usage

Just add Open Inventor geometry below the node and the will be rendered with shadows.

Details

This module requires OpenGL 2.0, GLSL 1.20 and texture arrays.

It makes use of the GLSL Shader Pipeline and extends the pipeline with a shadowed light. Currently only a single directional light is supported.

The “Percentage Closer Soft Shadow” (PCSS) mode uses code provided by NVidia which was ported to from HLSL to GLSL. This software contains source code provided by NVIDIA Corporation.

Windows

Default Panel

Input Fields

child

name: child, type: SoNode

Output Fields

self

name: self, type: SoNode

Parameter Fields

Field Index

Altitude: Float	Shadow Darkness: Float
Attach Light To Camera: Bool	Shadow Map Size: Integer
Azimuth: Float	Shadow Map Splits: Integer
Debug Depth Textures: Bool	Shadow Mode: Enum
Diffuse Color: Color	supported: Bool
Enabled: Bool
Penumbra Angle: Float
Replace Lighting: Bool

Visible Fields

Enabled

name: enabled, type: Bool, default: TRUE

Replace Lighting

name: replaceLighting, type: Bool, default: TRUE

Shadow Map Size

name: shadowMapSize, type: Integer, default: 2048

Defines the size of the shadow map (should be a power of two for better performance)

Shadow Map Splits

name: shadowMapSplits, type: Integer, default: 3, minimum: 1, maximum: 4

Defines the number of frustum splits (and thus the number of shadow maps that are generated), setting this to 1 results in standard shadow mapping. Using 4 splits takes most resources but allows scenes with very near and very far objects, while still rendering high detail shadows on the near objects.

Attach Light To Camera

name: attachLightToCamera, type: Bool, default: TRUE

If enabled, the light angles are relative to the viewing direction of the camera.

Altitude

name: lightPolarRho, type: Float, default: -45

The polar coordinate rho.

Azimuth

name: lightPolarPhi, type: Float, default: 45

The polar coordinate phi.

Diffuse Color

name: lightDiffuseColor, type: Color, default: 1 1 1

Defines the diffuse color of the directional light.

Shadow Darkness

name: shadowDarkness, type: Float, default: 0.80000001, minimum: 0, maximum: 1

Defines how dark the shadow is (1. means black, 0. means fully transparent)

Penumbra Angle

name: penumbraAngle, type: Float, default: 1, minimum: 0.1, maximum: 3

Defines the penumbra angle in degrees for the PCSS soft shadow mode.

Shadow Mode

name: shadowMode, type: Enum, default: PCF_GAUSSIAN_3X3

Defines how the shadow is rendered.

Values:

Title	Name	Description
Hard Shadows	SINGLE	A single shadow fetch is done. (Very sharp edges and aliasing).
Hard Shadows - PCF	PCF	Percent closer filtering done by the hardware (smoother edges).
Hard Shadows - PCF 4 Tap	PCF_4TAP	Four PCF samples are bilinear interpolated.
Hard Shadows - Gaussian 3x3	PCF_GAUSSIAN_3X3	A 3x3 Gaussian filter is used (using 9 PCF samples). This results in the smoothest shadow edges.
Percentage Closer Soft Shadows	PCSS	Percentage Closer Soft Shadow mapping as described in http://developer.download.nvidia.com/whitepapers/2008/PCSS_Integration.pdf The implementation uses a directional light which has a fixed penumbra slope angle.

Debug Depth Textures

name: debugDepthTextures, type: Bool, default: FALSE

If enabled, the cascaded shadow maps are rendered to the screen.

Hidden Fields

supported

name: supported, type: Bool, default: TRUE