Introduction

This section explains the Torque Lighting System's implementation of dynamic lighting and shadows in TGEA.

Dynamic Lighting

Most dynamic lighting features are shared between all versions of the Torque Lighting System and are covered in the Basic Lighting articles (which also cover static lighting).

There a several features specific to TGEA's implementation:

Lighting Shader Features

The Feature property determines which of the base material features (diffuse, bump, specular, cube mapping, ...) the dynamic light reproduces, which adds control over the light's visual impact and quality. Reducing features also improves rendering performance (see Dynamic Lighting Performance for details).

The lighting features are:

Full - reproduces the entire base material features
NoCube - reproduces all of the base material features except cube mapping
NoSpecCube - reproduces all of the base material features except cube mapping and specular highlights

Lighting Mask

The Mask Cube property allows a dynamic light to be filtered using the specified cube map texture. The mask is applied using modulation, meaning that white areas allow lighting to pass unaffected, while dark areas apply a shadowing effect. The effect also applies the filter's color to the light, so transparency effects like dirty, broken, and stained glass can be created.

Dynamic Shadows

The Torque Lighting System's dynamic shadow implementation casts shadows from dynamic DTS objects onto the world and the objects themselves (based on shadow quality and hardware availability). Dynamic shadows like all dynamic real-time effects create rendering overhead and should be used sparingly (see Performance Considerations for more details).

Different types of DTS objects (TSStatic, ShapeBase derived, ...) cast either static or dynamic shadows. To understand the differences and to find out which objects are best for your scene; see DTS Lighting and Shadows

Object shadows are adjusted using the following datablock properties:

shadowEnable - enables shadows on the object.
shadowCanMove - performance tweak that skips surface recalc when object is not moveable.
shadowCanAnimate - performance tweak that skips image recalc when object is not animated.
shadowSelfShadow - enables self-shadowing.
shadowDTSShadow - enables casting onto other DTS objects (requires self-shadowing, currently limited to other ShapeBase derived objects, ***see Note 1***)
shadowSize - shadow texture size (must be a power of two).
shadowAnimationFrameSkip - performance tweak that skips image recalc for X rendered frames (ignored when self-shadowing).
shadowMaxVisibleDistance - maximum distance from the viewer the shadow is visible.
shadowProjectionDistance - distance the shadow projects from the casting object.
shadowSphereAdjust - expands the shadow image out beyond the object bounding box by X times (for objects with bad bounding boxes).
shadowBias - adjusts the shadow's error correction.

Dynamic shadows automatically perform LOD transitions based on the distance from the viewer to improve performance when quality is not as critical. The LOD affects both shadow size and quality (disabling self-shadowing at a suitable distance).

Dynamic shadows can be reduced from multiple shadows-per-object to a single shadow with the user pref $pref::LightManager::sgMultipleDynamicShadows, or disabled with the user pref
$pref::LightManager::sgUseDynamicShadows.

Note 1: Unlike shadows cast on interiors, DTS to DTS shadowing cannot use depth partitioning. This means DTS objects can receive shadows through walls and other objects. To minimize this effect, use zoned lighting, reduce the casting object's shadow projection distance, rig lighting to avoid shadow casting lights near thin walls, floors, or ceilings, or design levels with thick walls, floors, and ceilings.

Dynamic Shadow Quality

Dynamic shadow quality is adjustable on several levels, including; per-object via datablock, automatically based on hardware support, and through the user quality pref

$pref::LightManager::sgDynamicShadowQuality (0 - high, 1 - medium, 2 - low), which limits the quality of all dynamic shadows, trading quality for performance.

High quality shadows perform self-shadowing and provide a nice soft shadow edge. High quality requires pixel shader 3.0 or higher, the user quality pref set to high (0), and the object set to self-shadow.

Medium quality shadows perform self-shadowing, but have a less smooth edge. Medium quality requires pixel shader 2.0 or higher, the user quality pref set to at least medium (1), and the object set to self-shadow.

Low quality shadows do not self-shadow, but provide a nice soft edge. Low quality is used on hardware with < pixel shader 2.0, when the user quality pref is set to low (2), or on objects that do not self-shadow.

Dynamic Shadow Size

Dynamic shadow size works similar to shadow quality, though it's not limited by hardware. An object's maximum shadow size is set using the datablock property shadowSize. The user shadow size pref $pref::LightManager::sgDynamicShadowDetailSize (0 - highest, 1 - next smaller size, ...) reduces the size of all shadows, trading quality for performance.

Tweaking Self-shadowing

Self-shadowing can cause some visual artifacts especially when using small shadow sizes, this can be reduced using the datablock property shadowBias. The default value is 0.0005 - increasing the value reduces any visual artifacts, while decreasing the value makes shadows more accurate.

Performance Considerations

See TGEA Performance Considerations.