Tessellation for Markups
Types
Functions
Detailed Description
- group a3d_tessmarkup
Tessellation for markups.
Entity type is kA3DTypeTessMarkup.
The tessellation uses two arrays: one for the codes and another for the coordinates. The codes array describes the type of contents in tessellation (the entities). The coordinates array contains point coordinates and other floating point values used by the entities. The coordinates array is specified in the A3DTessBaseData structure.
Each entity occupies at least two codes. The first code contains the entity type and the number of specific codes. The second code contains the number of doubles (coordinates) for the entity. The doubles (coordinates) are in the coordinates array of the A3DTessBaseData structure.
Explanation of the first code:
Use one of the following masks to identify the entity type with the first code:
kA3DMarkupIsMatrix denotes a matrix.
kA3DMarkupIsExtraData indicates other entities (extra data).
kA3DMarkupExtraDataType is the type of extra data.
kA3DMarkupIsMatrix must not be set if kA3DMarkupIsExtraData is set and kA3DMarkupExtraDataType represents the type of entity only if kA3DMarkupIsExtraData
is set.
The
kA3DMarkupIntegerMask mask represents the number of codes that refers to the entity (inner codes).kA3DMarkupIsMatrix and kA3DMarkupIsExtraData are booleans; whereas, kA3DMarkupExtraDataTypeis an integer.
The other bits should be set to zero.
See Bitmasks for A3DTessMarkupData tessellation and Extra data types for A3DTessMarkupData tessellation for more details.
Explanation of the second code:
The second code is the number of doubles needed by the entity. Each time the first double of block refers to updated position within BaseData Coord array: starting from 0 if reading a matrix first and next double value to read will be at Coord[16].
The following table describes the inner codes and doubles that can be defined for each entity. It also describes the extra data type number.
See A3D_ENCODE_EXTRA_DATA macro to encode extra data.Entity Extra data type Number of inner codes Number of doubles --------------------------------------------------------------------------------------------- Polyline none 0 number of points * 3 Matrix mode[1] none 0 or number in block 0 or number in block Pattern 0 3 + number of loops number of points in loops * 3 Picture 1 1 0 Triangles 2 0 number of triangles * 9 Quads 3 0 number of quads * 12 Face view mode[1] 6 0 or number in block 0 or number in block Frame draw mode[1] 7 0 or number in block 0 or number in block Fixed size mode[1] 8 0 or number in block 0 or number in block Symbol 9 1 3 Cylinder 10 0 3 Color 11 1 0 Line stipple[2] 12 0 or 1 0 Font 13 2 0 Text 14 1 2 Points 15 0 number of points * 3 Polygon 16 0 number of points * 3 Line width[2] 17 0 0 or 1
About Blocks
Blocks are defined by face view, frame draw, fixed size, and matrix modes (indicated by [1]). Each block is surrounded by the corresponding entity. At the start of a block, the entity modifies the state (style, current transformation matrix, …). Then this state is restored at the end of the block. For example, a matrix mode starts by defining a matrix (which will multiply the current transformation matrix), draws some entities, and ends with another matrix mode entity for indicating the end of the mode.
[1] The face view, frame draw, fixed size, and matrix modes start with the corresponding entity and end with the same entity; therefore, they define blocks. The starting entity has a non-zero number of inner codes. It represents the number of codes until the end of the block, excluding the 2 mandatory codes for each entity. The same rule applies to the doubles. The ending entity has 0 inner codes and 0 doubles. The use of this number is to easily skip a block when reading tessellation. To treat the content of a block, the numbers to use are as follows:
Mode Number of inner codes Number of doubles -------------------------------------------------------------------------------- Face view (starting) 0 3 Face view (ending) 0 0 Frame draw (starting) 0 3 Frame draw (ending) 0 0 Fixed size (starting) 0 3 Fixed size (ending) 0 0 Matrix (starting) 0 16 Matrix (ending) 0 0
For example: matrix mode
--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-- Codes | |M1|16|C |C |C |C |C |C |C |C |C |C |C |M2|0 | --+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--
M1 code is kA3DMarkupIsMatrix (0 additional code), which is the same as M2. This example shows the codes for defining a matrix mode. The M1 code defines the beginning of the matrix mode, and the M2 code defines the closing of that mode. The number of doubles for the M1 code is 16. After that, some entities are drawn (the Cs) and the M2 code defines the end of the matrix mode. The M2 code has 0 codes and 0 doubles because it is only reverting back to the initial matrix.
[2] The line stipple and line width modes operate identically to [1], but the numbers correspond to the entity only and not to the block. This is because the treatment of those can be more easily omitted than for the previous ones. For line stipple mode, the number of inner codes denotes the start (1) or the end (0) of the block. For line width mode, the number of doubles denotes the start (1) or the end (0) of the block.
Explanation of each entity:
The array for each entity is organized as described here:
First column shows the mandatory codes and the inner codes
Second column shows the doubles
There is a (x,y,z) triplet for each point of the polyline.Codes Doubles -------------------------------------------------------------------------------- 0 X number of points * 3 Y Z
Triangles
A list of triangles.
There is a (x,y,z) triplet for each point of the triangle list.Codes Doubles -------------------------------------------------------------------------------- 0 X number of triangles * 9 Y Z
Quads
A list of quads.
There is a (x,y,z) triplet for each point of the quad list.Codes Doubles -------------------------------------------------------------------------------- 0 X number of quads * 12 Y Z
Polygon
There is a (x,y,z) triplet for each point of the polygon.Codes Doubles -------------------------------------------------------------------------------- 0 X number of points * 3 Y Z
Points
A list of points.
There is a (x,y,z) triplet for each point.Codes Doubles -------------------------------------------------------------------------------- 0 X number of points * 3 Y Z
Face view mode
In this mode, all the drawing entities are parallel to the screen (billboard). The point given in the doubles corresponds to the origin of the new coordinate system in which we draw parallel to the screen.
Codes Doubles -------------------------------------------------------------------------------- 0 or number in block X 0 or number in block Y Z
Frame draw mode
In this mode, all the drawing entities are given in 2D space. The point given in the doubles corresponds to a 3D point projected onto the screen giving origin of 2D coordinate system in which we draw in 2D (viewport).
Codes Doubles -------------------------------------------------------------------------------- 0 or number in block X 0 or number in block Y Z
Fixed size mode
In this mode, all the drawing entities are drawn at a fixed size, independent of the zoom setting. The point given in the doubles corresponds to the origin of the new coordinate system in which we draw at fixed size.
Codes Doubles -------------------------------------------------------------------------------- 0 or number in block X 0 or number in block Y Z
Matrix mode
In this mode, all the drawing entities are transformed by the current transformation matrix multiplied by the matrix given in the doubles. At the end of the mode, the previously active transformation matrix is restored.
Codes Doubles -------------------------------------------------------------------------------- 0 or number in block a(1,1) 0 or number in block a(2,1) a(3,1) a(4,1) a(1,2) a(2,2) ... a(3,4) a(4,4)
Symbol
The point given in the doubles corresponds to the position of the symbol in 3D.
The pattern is an A3DGraphVPicturePatternData type. The pattern identifier is obtained by invoking the A3DGlobalInsertGraphVPicturePattern function.Codes Doubles -------------------------------------------------------------------------------- 1 X 3 Y id of pattern Z
Color
This entity defines a color that will be effective until a new one is defined.
Color identifier is obtained by invoking the A3DGlobalInsertGraphRgbColor function.Codes Doubles -------------------------------------------------------------------------------- 1 0 id of color
Line stipple mode
This entity defines the style that will be effective inside the block.
The first code is 1 for beginning the block and 0 for ending the block. The style identifier is obtained by invoking the A3DGlobalInsertGraphStyle function.Codes Doubles -------------------------------------------------------------------------------- 0 or 1 0 id of style
Font
This entity defines the font used for the Text entity (described next).
The indexes and the attributes are taken from the A3DFontKeyData structure. To create the A3DFontKeyData structure, invoke the A3DGlobalFontKeyCreate function.Codes Doubles -------------------------------------------------------------------------------- 2 0 family index style index/size index/attributes
The font style, size indexes, and attributes are encoded into a single code by using the bitmasks in Masks for encoding font keys. See Fonts.
Text
This entity defines a text string to be rendered with the current font (defined by A3DFontData entity).
The index of text refers to the zero-based text index in A3DTessMarkupData::m_ppcTextsCodes Doubles -------------------------------------------------------------------------------- 1 W 2 H index of text
.
The
W and H correspond to the width and height (respectively) of text in real display coordinates.See also
Line width mode
This entity defines the line width that will be effective inside the block.
The number of doubles is 1 for beginning the block and 0 for ending the block. The W double is the line width to use in the block. There is no W double when ending the block.Codes Doubles -------------------------------------------------------------------------------- 0 W 0 or 1
Cylinder
The cylinder is positioned by a matrix mode, oriented with Z axis, base at Z = 0 and top at Z = Height.Codes Doubles -------------------------------------------------------------------------------- 0 Base radius 3 Top radius Height
Picture
This entity defines a picture positioned at the current position.
Picture identifier is obtained by invoking the A3DGlobalInsertGraphPicture function.Codes Doubles -------------------------------------------------------------------------------- 1 0 id of picture
Pattern
The filled mode is one of these values:Codes Doubles -------------------------------------------------------------------------------- 3 + number of loops X number of points in loops * 3 Y id of pattern Z filled mode behavior number of points for loop 1 ... number of points for loop n
0=OR,1=AND, or2=XOR. The behavior is a bit field, with the 0x1 bit specifying whether to ignore the view transformation. If true, the pattern is not transformed by the current view transformation. The other bits should be set to zero. There is a (x,y,z) triplet for each point of loops, sequentially.Pattern identifier is created by invoking one of the following functions:
Function Documentation
-
A3DStatus A3DTessMarkupGet(const A3DTessMarkup *pTess, A3DTessMarkupData *pData)
Populates the A3DTessMarkupData structure.
- Version
2.0
- Return values:
A3D_INITIALIZE_NOT_CALLED –
A3D_INVALID_DATA_STRUCT_SIZE –
A3D_INVALID_DATA_STRUCT_NULL –
A3D_INVALID_ENTITY_NULL –
A3D_INVALID_ENTITY_TYPE –
A3D_SUCCESS –
- Returns:
A3D_SUCCESS in case of success or an error code
-
A3DStatus A3DTessMarkupCreate(const A3DTessMarkupData *pData, A3DTessMarkup **ppTess)
Creates an A3DTessMarkup entity from an A3DTessMarkupData structure.
- Version
2.0
- Return values:
A3D_INITIALIZE_NOT_CALLED –
A3D_INVALID_DATA_STRUCT_SIZE –
A3D_INVALID_DATA_STRUCT_NULL –
A3D_INVALID_ENTITY_NULL –
A3D_INVALID_ENTITY_TYPE –
A3D_TESSMARKUP_HAS_INVALID_FONTKEY –
A3D_TESSMARKUP_HAS_INVALID_TEXT_INDEX –
A3D_SUCCESS –
- Returns:
A3D_SUCCESS in case of success or an error code
