View source for Vertex (lx-vertex.hpp)

{{DISPLAYTITLE:vertex (lx_vertex.hpp)}}

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== Vertex Features ==

A vertex is a general concept spanning meshes, render surfaces, and particle simulation. A vertex is a point in a multi-dimensional space. Vertex features are named vectors describing aspects of the vertex. A vertex vector is the concatenation of the values of all of its features into a single array. A vertex description (also TableauVertex) lists the features of the vertex and their offset in the vertex vector.

Vertex feature categories indicate the context where the feature is expected to be valid. Currently that just surfaces and particles.

===== (1) SDK: LXsVFCAT_SURFACE, etc. defines =====

<syntaxhighlight>
 #define [[LXsVFCAT_SURFACE (index)|LXsVFCAT_SURFACE]]        "surface"
 #define [[LXsVFCAT_PARTICLE (index)|LXsVFCAT_PARTICLE]]       "particle"
</syntaxhighlight>

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A vector type can in theory be any string of unique character codes, but these are the most common and most likely supported.

===== (2) SDK: LXsVECTYPE_XY, etc. defines =====

<syntaxhighlight>
 #define [[LXsVECTYPE_XY (index)|LXsVECTYPE_XY]]           "XY"
 #define [[LXsVECTYPE_XYZ (index)|LXsVECTYPE_XYZ]]          "XYZ"
 #define [[LXsVECTYPE_RGB (index)|LXsVECTYPE_RGB]]          "RGB"
 #define [[LXsVECTYPE_RGBA (index)|LXsVECTYPE_RGBA]]         "RGBA"
 #define [[LXsVECTYPE_UV (index)|LXsVECTYPE_UV]]           "UV"
 #define [[LXsVECTYPE_UVW (index)|LXsVECTYPE_UVW]]          "UVW"
</syntaxhighlight>

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=== Tableau Vertex ===

A tableau vertex object encodes information about the structure of the vertex data for sampling elements.  Shaders and the renderer negotiate for the features they want from the element.  These are added to the vertex object and are given offsets into the master vector.  Once set, the vector can be queried for its total size, and for the offsets of each of the selected vertex features.

===== (3) SDK: TableauVertex::AddFeature, etc. =====

<syntaxhighlight>
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 AddFeature) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         LXtID4                   type,
         const char              *name,
         unsigned int            *index);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 Lookup) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         LXtID4                   type,
         const char              *name,
         unsigned int            *offset);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  unsigned int,
 Size) (
         [[LXtObjectID (index)|LXtObjectID]]              self);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  unsigned int,
 Count) (
         [[LXtObjectID (index)|LXtObjectID]]              self);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 ByIndex) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         unsigned int             index,
         LXtID4                  *type,
         const char             **name,
         unsigned int            *offset);
</syntaxhighlight>

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===== (4) SDK: CLxUser_TableauVertex::NewFeature method =====

<syntaxhighlight>
         int
 NewFeature (
         LXtID4                   type,
         const char              *name)
 {
         unsigned                 index;
         [[LxResult (index)|LxResult]]                 rc;
 
         rc = AddFeature (type, name, &index);
         if ([[LXx_OK (index)|LXx_OK]] (rc))
                 return index;
         else
                 return -1;
 }
</syntaxhighlight>

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===== (5) SDK: CLxUser_TableauVertex::GetOffset method =====

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         int
 GetOffset (
         LXtID4                   type,
         const char              *name)
 {
         unsigned                 offset;
         [[LxResult (index)|LxResult]]                 rc;
 
         rc = Lookup (type, name, &offset);
         if ([[LXx_OK (index)|LXx_OK]] (rc))
                 return offset;
         else
                 return -1;
 }
</syntaxhighlight>

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===== (6) SDK: LXu_TABLEAUVERTEX define =====

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 #define [[LXu_TABLEAUVERTEX (index)|LXu_TABLEAUVERTEX]]       "F90A0A39-EE2A-4D11-912B-9338EF271DFF"</syntaxhighlight>

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Empty TableauVertex Python user class.

===== (7) PY: empty TableauVertex user class =====

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 pass
</syntaxhighlight>

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=== Service ===

The vertex feature service provides methods for interrogating features.

===== (8) SDK: LXa_VERTEXFEATURESERVICE, etc. defines =====

<syntaxhighlight>
 #define [[LXa_VERTEXFEATURESERVICE (index)|LXa_VERTEXFEATURESERVICE]]        "vertexfeatureservice"
 #define [[LXu_VERTEXFEATURESERVICE (index)|LXu_VERTEXFEATURESERVICE]]        "B40D51A9-6C04-46D1-BA8A-0FE9B32EAC3C"</syntaxhighlight>

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===== (9) SDK: VertexFeatureService::ScriptQuery =====

<syntaxhighlight>
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 ScriptQuery) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         void                   **ppvObj);
</syntaxhighlight>

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Get a new, empty TableauVertex object.

===== (10) SDK: VertexFeatureService::AllocVertex =====

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         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 AllocVertex) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         void                   **ppvObj);
</syntaxhighlight>

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This gets the ident string for a vertex feature given the type and (optional) name.

===== (11) SDK: VertexFeatureService::Lookup =====

<syntaxhighlight>
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 Lookup) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         LXtID4                   type,
         const char              *name,
         const char             **ident);
</syntaxhighlight>

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Given the ident the various attributes of the feature can be read.

===== (12) SDK: VertexFeatureService::Type, etc. =====

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         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 Type) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         const char              *ident,
         LXtID4                  *type);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 Name) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         const char              *ident,
         const char             **name);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 Dimension) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         const char              *ident,
         unsigned                *dimension);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 VectorType) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         const char              *ident,
         const char             **vecType);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 DataType) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         const char              *ident,
         const char             **typeName);
 
         [[LXxMETHOD (index)|LXxMETHOD]](  [[LxResult (index)|LxResult]],
 TestCategory) (
         [[LXtObjectID (index)|LXtObjectID]]              self,
         const char              *ident,
         const char              *category);
</syntaxhighlight>

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===== (13) SDK: empty VertexFeatureService User Class =====

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Empty vertes service Python user class.

===== (14) PY: empty Service.VertexFeature user class =====

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 pass
</syntaxhighlight>

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== Feature Packages ==

For some subset of features we define packages. If an item type wants to be able to use a package it should set this server tag to the feature category.

===== (15) SDK: LXsPKG_USEFEATURES define =====

<syntaxhighlight>
 #define [[LXsPKG_USEFEATURES (index)|LXsPKG_USEFEATURES]]      "package.useFeatures"
</syntaxhighlight>

These packages have names that are derived from the ident and the read-only flag.

[[Category:Headers]]
[[Category:Autogenerated]]