The AdvancedAppearance node enables you to use advanced texturing techniques such as multiple texturing.

Node description

AdvancedAppearance { 
   exposedField   SFNode	material		NULL 
   exposedField   MFNode	textures		[] 
   exposedField   MFString	mappingTypes	[] 
   exposedField   MFFloat	weights		[]	# [0, inf)
   exposedField   SFFloat	materialBlending	0	# [0, 1] 
   exposedField   MFNode	textureTransforms	[]
   exposedField   MFString	backgroundFactor	[]
   exposedField   MFString	foregroundFactor	[]
}

material The material field, if specified, contains a Material node.

textures The textures field specifies a set of 2D textures for multi-texturing. The texture field, if specified, contains one of the various types of texture nodes (ImageTexture, MovieTexture, or PixelTexture). If the texture node is NULL or the texture field is unspecified, the object that references this Appearance is not textured.

mappingTypes The mappingTypes field defines a texture map type. The possible types are: "SIMPLE" - ordinary mapping that all VRML browsers support, "ENVIRONMENT" - this simulates the reflecting surfaces. When there are several textures with the "SIMPLE" map type, it is possible to define individual mapping for each texture by using several sets of texture indexes in the texCoordIndex field of the geometry node. The texCoordIndex field may contain N * L indexes, where N is the number of textures with the "SIMPLE" map type, L - the number of indexes in the coordIndex field. For textures with the "ENVIRONMENT" map type texture indexes are not used.

weights The weights field specifies a set of weights that are required to mix different textures. In Cortona 4.0 this field is ignored and the backgroundFactor and foregroundFactor fields are used for mixing textures.

materialBlending The materialBlending field specifies how to combine textures and materials on associated geometry. The value of materialBlending ranges from 0 to 1. If you don't specify any textures (the textures field is empty) or material (material is NULL), no combination happens. The weights required for mixing can be computed as: if(textures.count == 0) Wmaterial = 1; // a material is used else if(material == NULL) Wmaterial = 0; // textures are used else // textures and material are combined Wmaterial = materialBlending.

textureTransforms The textureTransforms field specifies a set of 2D transformations that are applied to different textures that are specified in the textures field. The field, if specified, contains a list of TextureTransform nodes. Descriptions of the TextureTransform node are provided in the VRML97 specification (see 6.49, TextureTransform).

BackgroundFactor, foreGroundFactor The backgroundFactor and foreGroundFactor fields specify the sets of factors required to mix textures.

CMT(i) = CB * FB(i) + CF * FF(i), where
	CMT(i)	- the color resulting from the given pass,
	i	- the texture number in the textures node (the pass number),
	CB	- the pixel color resulting from the previous pass (CMT(i - 1)),
		  or back color (the frame-buffer contents before rendering)
		  for the first pass,
	CF	- the pixel color of the texture with the number i,
	FB(i)	- the factor defined in the backgroundFactor field,
	FF(i)	- the factor defined in the foregroundFactor field.

Value	Factor
DEFAULT	default
ZERO	0
ONE	1
FORE_COLOR	CF
INV_FORE_COLOR	1 - CF
FORE_ALPHA	AF
INV_FORE_ALPHA	1 - AF
BACK_COLOR	CB
INV_BACK_COLOR	1 - CB
BACK_ALPHA	AB
INV_BACK_ALPHA	1 - AB

A_F - the alpha value resulting from the given pass,
A_B - the alpha value resulting from the previous pass or from the back color. (If there is no alpha channel A_B = 1).

Only GeForce adapters support the last two values. So for the rest display adapters the "BACK_ALPHA" value is equivalent to "ONE", and "INV_BACK_ALPHA" is equivalent to "ZERO".

If the values in the backgroundFactor and foreGroundFactor fields are not defined or set to "DEFAULT", they are determined by default according to the texture type (see the table below). The value of C_F also depends on the texture type. If the material is defined (lighting on), the intensity textures are modulating by the diffuse color of the material. If all textures have alpha channels, the material transparency is ignored i.e. it is considered to be 0, and alpha from the textures is used. But if there is at least one texture without alpha the material transparency modulates the alpha channel of all textures.

Texture type	backgroundFactor by default	foregroundFactor by default	CF lighting on	CF lighting off
Intensity	"ZERO"	"ONE"	DM * CT	CT
Intensity + Alpha	"INV_FORE_ALPHA"	"FORE_ALPHA"	DM * CT	CT
RGB	"ZERO"	"ONE"	CT	CT
RGB + Alpha	"INV_FORE_ALPHA"	"FORE_ALPHA"	CT	CT

 AF = AT * (1 - TM), where
	AT    - the alpha value of the texture 
			(for 1- and 3-component textures AT = 1)      
	TM    - the Material.transparency field value 
			(or 0 if all textures have the alpha channel)      

The color obtained after multi-texturing C_MT is processed in the following way:

Lighting off The resulting color is calculated by the formula: C = BM * EM + (1 - BM) * CMT, where C - is the resulting color of the pixel, BM - is the coefficient of the material blending (the materialBlending field), EM - is the emissive color of the material (the Material.emissiveColor field).

Lighting on The resulting color of the pixel is calculated by the standard formula of the VRML lighting model where a diffuse factor (ODrgb) is set to the following color: ODrgb = BM * DM + (1 - BM) * CMT The resulting color Ñ is combined with the color resulting from the previous pass (which is equal to CMT) and with the transparency of Material (the Material.transparency field) according to the following formula: (1 - TM) * C + TM * CMT

Examples

scene size: 692bytes resources size: 4.9KB archive size: 5.7KB

scene size: 7.9KB resources size: 28KB archive size: 30KB