This property node defines a 3D texture map and parameters for that map. This map is used to apply a 3D texture to subsequent shapes as they are rendered.

The texture can be read from the file(s) specified by the OIV.Inventor.Nodes.SoTexture3.filenames field. Once the texture has been read, the OIV.Inventor.Nodes.SoTexture3.images field contains the texture data. However, this field is marked so the image is not written out when the texture node is written to a file. To turn off texturing, set the first value of the OIV.Inventor.Nodes.SoTexture3.filenames field to an empty string ("").

Textures can also be specified in memory by setting the OIV.Inventor.Nodes.SoTexture3.images field to contain the texture data. Doing so resets the OIV.Inventor.Nodes.SoTexture3.filenames field to the empty string.

Simply put, a 3D texture is a set of well-arranged 2D textures. Typically, 3D textures represent a set of image-slices of a given volume of data, and are used for mapping onto pieces of geometry. Note that this is different from direct volume rendering in that 3D textures need to be mapped onto a piece of geometry.

OpenGL requires all images in a 3D texture to have the same dimensions, and each dimension (X, Y, and Z) needs to be a power of 2. Also, images must have the same number of components (grayscale, grayscale with transparency, RGB, or RGB with transparency).

• Images that do not have the same number of components as the first image are recomputed to have the same number of components. At best, there is no loss of quality. At worst, the recomputed images may lose colors and/or transparency.

• If the 2D texture image's width or height is greater than the maximum supported by OpenGL, then the image will be clipped at the maximum texture size.

• If one or more of the dimensions is not a power of 2, the texture is enlarged (it is never shrunk) to fit the power-of-2 requirement. Note that, unlike 2D textures where a resized texture is actually rescaled, the 3D image is not rescaled. Instead, black pixels are added to the edge of the image.

You should take this into account when setting texture coordinates. If your 3D image is not correctly dimensioned, you may want to consider either applying a ratio to your coordinates or adding an OIV.Inventor.Nodes.SoTexture3Transform node with the field scaleFactor set to compensate.

• Images that have a different size from the first image are resized (clipped or augmented) to match the size of the first image (which itself may have been resized to satisfy the size requirements of OpenGL).

• If the number of images (the depth of the 3D texture) is not a power of 2, an error is issued and the nearest power of 2 is chosen. If it is lower, some images are discarded; if it is higher, new images are created and filled with zeros.

The quality of the texturing is affected by the textureQuality field of the OIV.Inventor.Nodes.SoComplexity node. The textureQuality field affects what kind of filtering is done to the texture when it must be minified or magnified. The mapping of a particular texture quality value to a particular OpenGL filtering technique is implementation dependent, and varies based on the texturing performance. If mipmap filtering is required, mipmaps are automatically created using the simple box filter.

Transparency Texture images can contain transparency (alpha values less than 1) and modify the transparency of geometry in the scene. Also note that some image file formats, for example JPEG, do not support transparency information (alpha channel).

LIMITATIONS

3D textures are only supported by the following shapes:

• OIV.Inventor.Nodes.SoIndexedFaceSet

• OIV.Inventor.Nodes.SoIndexedQuadMesh

• OIV.Inventor.Nodes.SoIndexedTriangleStripSet

• OIV.Inventor.Nodes.SoFaceSet

• OIV.Inventor.Nodes.SoQuadMesh

• OIV.Inventor.Nodes.SoTriangleStripSet

• OIV.Inventor.Nodes.SoBufferedShape

Only OIV.Inventor.Nodes.SoIndexedFaceSet shapes automatically compute texture coordinates if they are not specified either by a texture coordinate function (see OIV.Inventor.Nodes.SoTextureCoordinateFunction) or by explicit texture coordinates (see OIV.Inventor.Nodes.SoTextureCoordinate3).

FILE FORMAT/DEFAULT

Texture3 {

filenames	""
enableCompressedTexture	false
images	0 0 0 0
wrapS	REPEAT
wrapT	REPEAT
wrapR	REPEAT
model	MODULATE
blendColor	0 0 0
enableBorder	false
borderColor	0 0 0 1
maxAnisotropy	1.0
minFilter	AUTO
magFilter	AUTO
useAutoMipmap	false
internalFormat	AUTO_INTERNAL_FORMAT
layout	VOLUME

}

ACTION BEHAVIOR

OIV.Inventor.Actions.SoGLRenderAction, OIV.Inventor.Actions.SoCallbackAction Sets current texture in state. Sets: OIV.Inventor.Elements.SoTextureImage3Element

Reference