A3DTessFaceData

struct A3DTessFaceData

Structure that describes basic entities of a face in a solid or surface mesh representations.

2.0

In the context of solid or surface mesh representations, an entity can be any number of triangles. If more than one, they maybe organized as a fan or strip.

The m_uiStyleIndexesSizemember has these values:

• 0 indicates that there are no graphics (in this case, all graphics are inherited from the owner (parent) of the A3DTess3DData).
• 1 indicates that one graphic is associated with the face.
• Greater than 1 indicates that the number of graphics is linked to the number of entities in the m_puiSizesTriangulatedmember.

Wireframe representation

The following A3DTessFaceDatamembers are used to describe a wireframe representation:

• m_uiStartWire: The starting index for the wire in the array of point indexes of the A3DTess3DData.
• m_puiSizesWires: Array of the number of indexes for each wire edge of the face, where the number of indexes is OR’d with the relevant flags kA3DTessFaceDataWireIsNotDrawnand/or kA3DTessFaceDataWireIsClosing.

Consider an example of an A3DTessFaceDatastructure in which both loops describe closed wire edges:

• First edge has 16 points (0x10).
• Second edge has 32 points (0x20).
• First loop consists of two wire edges:
• Second loop is one edge having 18 points (0x12).

For this example, the m_puiSizesWiresarray has these entries:[0x0010, 0x8020, 0x8012]. The second and third array entries are the number of edges OR’d with the kA3DTessFaceDataWireIsClosing(0x8000). Notice that the indexes for each edge’s extremity are always stored. Therefore, the last point of the first edge is followed by the first point of the second edge.

In an A3DTessFaceDatastructure, the size of a wire edge is limited to 16383(0x3FFF) points.

Solid representation

The following A3DTessFaceDatamembers are for solid representations:

• m_usUsedEntitiesFlags(see Bitmasks for Specifying Tessellation Types): This flag specifies how to interpret the array m_puiSizesTriangulated.
• m_uiStartTriangulated: Starting index for the triangulated data in the array of point indexes of the A3DTess3DData.
• m_puiSizesTriangulated: Array of the number of indexes for each triangulated entity of the face.The triangulated data sizes are stored following the order of values in Bitmasks for Specifying Tessellation Types. Thus, the triangles are stored before triangle fans and before textured triangles.
• For triangle types, the m_puiSizesTriangulatedmember specifies the number of triangles.
• For triangle fan and strips types, the m_puiSizesTriangulatedmember specifies the number of fans or strips followed by the number of points for each of them.

Consider an example of an A3DTessFaceDatastructure that describes five triangles, two fans of 5 and 7 points respectively, and one strip of 11 indexes. For this example, set m_usUsedEntitiesFlagsto kA3DTessFaceDataTriangle& kA3DTessFaceDataTriangleFan& kA3DTessFaceDataTriangleStripe. In this case, m_puiSizesTriangulatedwill be [5,2,5,7,1,11].

In case of the tessellation types kA3DTessFaceData*OneNormal*(i.e., one of the bitmasks specifying a tessellation type with one normal), the number of points can bear the flag kA3DTessFaceDataNormalSingle, modifying the way of reading normals information. In such a case, you must use kA3DTessFaceDataNormalSingleto characterize status and kA3DTessFaceDataNormalMaskto access the real value.

The following A3DTessFaceDatamembers also apply to solid representations:

• m_pucRGBAVertices: Colors stored directly on vertices. Either there is no color on vertices or every vertex must bear a color. Therefore, m_uiRGBAVerticesSizeis either 0 or equal to the number of point indexes as calculated from m_puiSizesTriangulated, multiplied by 3 if RGB, by 4 if RGBA. (In the previous example, m_uiRGBAVerticesSizeis 38*(m_bIsRGBA?4:3) = (5*3 + 5 + 7 + 11)*(m_bIsRGBA?4:3)).
• m_bIsRGBA: If true, the color scheme is RGBa; otherwise, it is RGB.
• m_usBehaviour: This member denotes the graphics behavior for this A3DTessFaceDatatowards owning entity in the tree, as described in Bit Field for Behavior on Graphics. For face behavior, kA3DGraphicsShowand kA3DGraphicsRemovedare not currently supported.
• m_uiTextureCoordIndexesSize: Number of texture coordinate indexes (see Bitmasks for Specifying Tessellation Types).

Index

Variables

• m_uiStyleIndexesSize
• m_puiStyleIndexes
• m_uiStartWire
• m_uiSizesWiresSize
• m_puiSizesWires
• m_usUsedEntitiesFlags
• m_uiStartTriangulated
• m_uiSizesTriangulatedSize
• m_puiSizesTriangulated
• m_bIsRGBA
• m_uiRGBAVerticesSize
• m_pucRGBAVertices
• m_usBehaviour
• m_uiTextureCoordIndexesSize

Variables

A3DUns32 A3DTessFaceData.m_uiStyleIndexesSize

A3DUns32

The size of m_puiStyleIndexes.

A3DUns32 *A3DTessFaceData.m_puiStyleIndexes

A3DUns32*

Array of display styles.

See explanations above.

A3DUns32 A3DTessFaceData.m_uiStartWire

A3DUns32

See explanations above.

A3DUns32 A3DTessFaceData.m_uiSizesWiresSize

A3DUns32

The size of m_puiSizesWires.

A3DUns32 *A3DTessFaceData.m_puiSizesWires

A3DUns32*

See explanations above.

A3DUns16 A3DTessFaceData.m_usUsedEntitiesFlags

A3DUns16

Bit field containing list of used entities in current face tessellation.

See explanations above.

Bitmasks for Specifying Tessellation Types

A3DUns32 A3DTessFaceData.m_uiStartTriangulated

A3DUns32

See explanations above.

A3DUns32 A3DTessFaceData.m_uiSizesTriangulatedSize

A3DUns32

The size of m_puiSizesTriangulated.

A3DUns32 *A3DTessFaceData.m_puiSizesTriangulated

A3DUns32*

See explanations above.

A3DBool A3DTessFaceData.m_bIsRGBA

A3DBool

A value of true specifies that the array is made of RGBA.

A value of false indicates that it is made of RGB.

A3DUns32 A3DTessFaceData.m_uiRGBAVerticesSize

A3DUns32

The size of m_pucRGBAVertices.

A3DUns8 *A3DTessFaceData.m_pucRGBAVertices

A3DUns8*

See explanations above.

A3DUns16 A3DTessFaceData.m_usBehaviour

A3DUns16

See explanations above.

A3DUns32 A3DTessFaceData.m_uiTextureCoordIndexesSize

A3DUns32

See explanations above.