class Geo::TriGroupSelection

Utility for doing vertex-based chart identification.

This is the code used as part of the precompute for identifying the tri groups (aka charts) in an Enlighten::IPrecompInputMesh mesh for mesh projection and packing into lightmaps. It identifies tri groups based on the index buffer and a set of explicit links. It holds the chart information in two forms for convenience:

1. A set of identified charts, with a list of triangle indices for each.

2. An array of chart indices to match the vertex array.

A triangle group is any group of triangles that do not share vertices with any other group. This definition allows us to operate on groups independently without having to worry about the changes to one group affecting another.

There are two reasons triangles may be joined together into the same group:

1. They share vertices and therefore cannot be separated

2. They reference vertices that are explicitly linked together

The index buffer specifies all the information we need to determine which vertices are between triangles. Additional explicit links can also be added as an array of index pairs. The explicit links allow an opportunity to remove any unnecessary vertex duplication that may exist, such as vertices being duplicated to incorporate additional irrelevant data. Note that the actual vertex data is not required.

Variables

Functions

static TriGroupSelection* Geo::TriGroupSelection::Create

public: TriGroupSelection * Create
(
    const Geo::s32 numVertices,
    const Geo::s32 * indexBuffer,
    Geo::s32 numIndices,
    const IdxLink * linkBuffer,
    Geo::s32 numLinks,
    const Geo::s16 * chartTags,
    const Geo::u8 * faceTypes
)

Create a tri group selection.

Parameters

static TriGroupSelection* Geo::TriGroupSelection::CreateExplicit

public: TriGroupSelection * CreateExplicit
(
    const Geo::s32 numVertices,
    const Geo::s32 numGroups,
    Geo::s32 * numTrisInTriGroup,
    Geo::s32 * triGroupBufferOffset,
    Geo::s32 * sharedTriIdxBuffer,
    Geo::s32 * vertexGroupIdxArray,
    Geo::s16 * chartTags,
    Geo::u8 * chartTypes
)

Explicitly construct a TriGroupSelection from ready-made arrays.

This provides a means to wrap a TriGroupSelection object around a set of arrays that match the internal structure of this class. This function takes ownership of the arrays and will delete them on exit. The parameters correspond to the m_ member variable namesakes. Note that this function does no error checking so the caller must ensure the data is correctly structured.

Geo::s16 Geo::TriGroupSelection::GetChartTagForGroupIdx

public: Geo::s16 GetChartTagForGroupIdx
(
    Geo::s32 groupIdx
) const

Gets the chart tag for the given TriGroup index.

Parameters

Geo::u8 Geo::TriGroupSelection::GetGroupTypeForGroupIdx

public: Geo::u8 GetGroupTypeForGroupIdx
(
    Geo::s32 groupIdx
) const

Gets the group type for the given TriGroup index.

Parameters

Geo::s32 Geo::TriGroupSelection::GetNumTriGroups

public: Geo::s32 GetNumTriGroups() const

Get the number of tri groups.

Geo::s32 Geo::TriGroupSelection::GetNumTrisInGroupIdx

public: Geo::s32 GetNumTrisInGroupIdx
(
    Geo::s32 groupIdx
) const

Returns the number of tris in the tri group specified by groupIdx.

Parameters

Returns

The number of tris or -1 if groupIdx is out of range.

const Geo::s32* Geo::TriGroupSelection::GetPerVertexGroupIdxArray

public: const Geo::s32 * GetPerVertexGroupIdxArray() const

Access the array of group indices with the same length and format as the vertex buffer Will be null if numVertices was 0.

Geo::s32 Geo::TriGroupSelection::GetPerVertexGroupIdxArrayLength

public: Geo::s32 GetPerVertexGroupIdxArrayLength() const

The length of the per vertex group idx array.

This is the same as numVertices passed in during Create()

const Geo::s32* Geo::TriGroupSelection::GetTriIdxArrayForGroupIdx

public: const Geo::s32 * GetTriIdxArrayForGroupIdx
(
    Geo::s32 groupIdx
) const

Get an array of triangle indices that comprise the group.

Because all the vertices in a triangle are linked into the same group by definition we only need to store the indices of the triangles in a group. So all elements of the set {indexBuffer[i * 3 + 0..2]}, where i is a triangle index, will be in the same group. This class doesn't currently provide group indices in an index buffer format, but this can be easily and efficiently reconstructed from this data.

Parameters

Returns

The array of triangle indices.

void Geo::TriGroupSelection::Release

public: void Release()

Release the object.

void Geo::TriGroupSelection::SetGroupTypeForGroupIdx

public: void SetGroupTypeForGroupIdx
(
    Geo::s32 groupIdx,
    Geo::u8 groupType
)

Sets the group type for the given TriGroup index.