rasterizer/core/tessellator.hpp

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*/

#pragma once
//=================================================================================================================================
// Microsoft D3D11 Fixed Function Tessellator Reference - May 7, 2012
// amar.patel@microsoft.com
//
// CHWTessellator demonstrates what is expected of hardware in the D3D11 fixed function Tessellator stage.  Hardware
// implementers need only look at this class.
//
// CHLSLTessellator is a wrapper for CHWTessellator, representing the effect of shader code that will
// be autogenerated by HLSL in the Hull Shader, both for plumbing data around, and to precondition TessFactor values before they
// are passed to the hardware (such as deriving inside TessFactors from edge TessFactors).  The algorithms used
// in CHLSLTessellator are subject to change, but since they represent shader code auto-generated by the HLSL compiler,
// CHLSLTessellator has no effect on hardware design at all.  Note the HLSL compiler will expose all the raw hardware
// control illustrated by CHWTessellator for those who don't need the helper functionality illustrated by CHLSLTessellator.
//
// Usage:        (1) Create either a CHLSLTessellator or CHWTessellator object, depending on which you want to verify.
//               (2) Call C*Tessellator::Init()
//               (3) Call C*Tessellator::Tessellate[IsoLine|Tri|Quad]Domain()
//                      - Here you pass in TessFactors (how much to tessellate)
//               (4) Call C*Tessellator::GetPointCount(), C*Tessellator::GetIndexCount() to see how much data was generated.
//               (5) Call C*Tessellator::GetPoints() and C*Tessellator::GetIndices() to get pointers to the data.
//                   The pointers are fixed for the lifetime of the object (storage for max tessellation),
//                   so if you ::Tessellate again, the data in the buffers is overwritten.
//               (6) There are various other Get() methods to retrieve TessFactors that have been processed from
//                   what you passed in at step 3.  You can retrieve separate TessFactors that the tessellator
//                   produced after clamping but before rounding, and also after rounding (say in pow2 mode).
//                   These numbers can be useful information if you are geomorphing displacement maps.
//               (7) Goto Step 2 or 3 if you want to animate TessFactors or tessellate a different patch
//
// Code implementation details:
//
// There is lots of headroom to make this code run faster on CPUs.  It was written merely as a reference for
// what results hardware should produce, with CPU performance not a consideration.  It is nice that this implementation
// only generates the exact number of vertices needed (no duplicates) in the output vertex buffer.  Also, the number
// of calculations done for each U/V domain coordinate is minimized by doing some precalculation of some patch or edge
// invariant numbers (see TESS_FACTOR_CONTEXT).  All the vertex coordinate calculations could be computed with as much
// parallelism as you like.  Similarly the calculation of connectivity itself is highly parallelizable, and can also
// be done independent of the vertex calculations.
//
//=================================================================================================================================

#define D3D11_TESSELLATOR_MIN_ODD_TESSELLATION_FACTOR 1
#define D3D11_TESSELLATOR_MAX_ODD_TESSELLATION_FACTOR 63
#define D3D11_TESSELLATOR_MIN_EVEN_TESSELLATION_FACTOR 2
#define D3D11_TESSELLATOR_MAX_EVEN_TESSELLATION_FACTOR 64

#define D3D11_TESSELLATOR_MIN_ISOLINE_DENSITY_TESSELLATION_FACTOR 1
#define D3D11_TESSELLATOR_MAX_ISOLINE_DENSITY_TESSELLATION_FACTOR 64

#define D3D11_TESSELLATOR_MAX_TESSELLATION_FACTOR 64 // max of even and odd tessFactors

#define MAX_POINT_COUNT ((D3D11_TESSELLATOR_MAX_TESSELLATION_FACTOR+1)*(D3D11_TESSELLATOR_MAX_TESSELLATION_FACTOR+1))
#define MAX_INDEX_COUNT (D3D11_TESSELLATOR_MAX_TESSELLATION_FACTOR*D3D11_TESSELLATOR_MAX_TESSELLATION_FACTOR*2*3)

//=================================================================================================================================
// Data types for the caller
//=================================================================================================================================
enum D3D11_TESSELLATOR_PARTITIONING
{
    D3D11_TESSELLATOR_PARTITIONING_INTEGER,
    D3D11_TESSELLATOR_PARTITIONING_POW2,
    D3D11_TESSELLATOR_PARTITIONING_FRACTIONAL_ODD,
    D3D11_TESSELLATOR_PARTITIONING_FRACTIONAL_EVEN
};

enum D3D11_TESSELLATOR_REDUCTION
{
    D3D11_TESSELLATOR_REDUCTION_MIN,
    D3D11_TESSELLATOR_REDUCTION_MAX,
    D3D11_TESSELLATOR_REDUCTION_AVERAGE
};

enum D3D11_TESSELLATOR_QUAD_REDUCTION_AXIS
{
    D3D11_TESSELLATOR_QUAD_REDUCTION_1_AXIS,
    D3D11_TESSELLATOR_QUAD_REDUCTION_2_AXIS
};

enum D3D11_TESSELLATOR_OUTPUT_PRIMITIVE
{
    D3D11_TESSELLATOR_OUTPUT_POINT,
    D3D11_TESSELLATOR_OUTPUT_LINE,
    D3D11_TESSELLATOR_OUTPUT_TRIANGLE_CW,
    D3D11_TESSELLATOR_OUTPUT_TRIANGLE_CCW,
};

typedef struct DOMAIN_POINT
{
    float u;
    float v; // for tri, w = 1 - u - v;
} DOMAIN_POINT;

//=================================================================================================================================
// CHWTessellator: D3D11 Tessellation Fixed Function Hardware Reference
//=================================================================================================================================
typedef unsigned int FXP; // fixed point number

class CHWTessellator
{

//---------------------------------------------------------------------------------------------------------------------------------
public:
    void Init( D3D11_TESSELLATOR_PARTITIONING         partitioning,
               D3D11_TESSELLATOR_OUTPUT_PRIMITIVE     outputPrimitive);

    void TessellateIsoLineDomain( float TessFactor_V_LineDensity,
                                  float TessFactor_U_LineDetail );

    void TessellateTriDomain( float TessFactor_Ueq0,
                              float TessFactor_Veq0,
                              float TessFactor_Weq0,
                              float TessFactor_Inside );

    void TessellateQuadDomain( float TessFactor_Ueq0,
                               float TessFactor_Veq0,
                               float TessFactor_Ueq1,
                               float TessFactor_Veq1,
                               float TessFactor_InsideU,
                               float TessFactor_InsideV );

    int GetPointCount();
    int GetIndexCount();

    DOMAIN_POINT* GetPoints(); // Get CHWTessellator owned pointer to vertices (UV values).
                               // Pointer is fixed for lifetime of CHWTessellator object.
    int* GetIndices();         // Get CHWTessellator owned pointer to vertex indices.
                               // Pointer is fixed for lifetime of CHWTessellator object.

#define ALLOW_XBOX_360_COMPARISON // Different vertex splitting order. This is NOT D3D11 behavior, just available here for comparison.
	                              // Setting this define true just allows the XBox split style to be enabled via
	                              // SetXBox360Mode() below, but by default this XBox360 mode still always starts off DISABLED.
								  // The XBox360 always splits from the center of an edge (D3D11 uses ruler function).  Splitting
	                              // from the center causes sliver triangles in transition areas, which cause numerous problems.
                                  // Note the XBox360 only supports adaptive tessellation via fractional_even partitioning,
                                  // though this #define lets you try the XBox vertex splitting order with any of the
                                  // partitioning modes: even, odd, integer or pow2.
#ifdef ALLOW_XBOX_360_COMPARISON
    void SetXBox360Mode(bool bXboxMode) {m_bXBox360Mode = bXboxMode;}
#endif
    CHWTessellator();
    ~CHWTessellator();
//---------------------------------------------------------------------------------------------------------------------------------
    //=============================================================================================================================
    // Some defines so that numbers are usually self commenting
    //=============================================================================================================================
    static const int U = 0; // points on a tri patch
    static const int V = 1;
    static const int W = 2;
    static const int Ueq0 = 0; // edges on a tri patch
    static const int Veq0 = 1;
    static const int Weq0 = 2;

    static const int Ueq1 = 2; // edges on a quad patch: Ueq0, Veq0, Ueq1, Veq1
    static const int Veq1 = 3;

    static const int QUAD_AXES = 2;
    static const int QUAD_EDGES = 4;
    static const int TRI_EDGES = 3;
    //=============================================================================================================================

    enum TESSELLATOR_PARITY // derived from D3D11_TESSELLATOR_PARTITIONING
    {                               // (note: for integer tessellation, both parities are used)
        TESSELLATOR_PARITY_EVEN,
        TESSELLATOR_PARITY_ODD
    };
private:
    TESSELLATOR_PARITY                   m_originalParity; // user chosen parity
    TESSELLATOR_PARITY                   m_parity; // current parity: if allowing mix of even/odd during discrete
                                                   // tessellation, this can vary from the user defined parity
    D3D11_TESSELLATOR_PARTITIONING       m_originalPartitioning; // user chosen partitioning
    D3D11_TESSELLATOR_PARTITIONING       m_partitioning; // current partitioning.  IsoLines overrides for line density
    D3D11_TESSELLATOR_OUTPUT_PRIMITIVE   m_outputPrimitive;
    DOMAIN_POINT*                        m_Point; // array where we will store u/v's for the points we generate
    int*                                 m_Index; // array where we will store index topology
    int                                  m_NumPoints;
    int                                  m_NumIndices;
#ifdef ALLOW_XBOX_360_COMPARISON
    bool                                 m_bXBox360Mode;
#endif
    // PlacePointIn1D below is the workhorse for all position placement.
    // It is code that could run as preamble in a Domain Shader, so the tessellator itself
    // doesn't necessarily need to have floating point.
    // Some per-TessFactor fixed context is needed, and that can be computed wherever
    // the TessFactor reduction is done, perhaps as Hull Shader postamble - this is shared
    // for all point evaluation.
    typedef struct TESS_FACTOR_CONTEXT
    {
        FXP fxpInvNumSegmentsOnFloorTessFactor;
        FXP fxpInvNumSegmentsOnCeilTessFactor;
        FXP fxpHalfTessFactorFraction;
        int numHalfTessFactorPoints;
        int splitPointOnFloorHalfTessFactor;
    } TESS_FACTOR_CONTEXT;
    void ComputeTessFactorContext( FXP fxpTessFactor, TESS_FACTOR_CONTEXT& TessFactorCtx );
    void PlacePointIn1D( const TESS_FACTOR_CONTEXT& TessFactorCtx, int point, FXP& fxpLocation );

    int NumPointsForTessFactor(FXP fxpTessFactor);

    // Tessellation parity control
    bool Odd() {return (m_parity == TESSELLATOR_PARITY_ODD) ? true : false;}
    void SetTessellationParity(TESSELLATOR_PARITY parity) {m_parity = parity;}

    // HWIntegerPartitioning() - hardware doesn't care about what pow2 partitioning is - the query below is true for
    //                           both integer and pow2.
    bool HWIntegerPartitioning() {return ((m_partitioning == D3D11_TESSELLATOR_PARTITIONING_INTEGER)||
                                          (m_partitioning == D3D11_TESSELLATOR_PARTITIONING_POW2)) ? true : false;}

    // Tesselation Partitioning control
    void RestorePartitioning() {m_partitioning = m_originalPartitioning;};
    void OverridePartitioning(D3D11_TESSELLATOR_PARTITIONING partitioning) {m_partitioning = partitioning;} //isoline uses this for density

    // Call these to generate new points and indices.  Max TessFactor storage is already allocated.
    int DefinePoint(FXP u, FXP v, int pointStorageOffset);
    void DefineIndex(int index, int indexStorageOffset);
    void DefineClockwiseTriangle(int index0, int index1, int index2, int indexStorageBaseOffset);

    // Couple of trivial ways to generate index data just given points and no other connectivity.
    void DumpAllPoints();                  // Make point indices for point rendering mode -
                                           // redundant, but just here for orthogonality.
    void DumpAllPointsAsInOrderLineList(); // A debug visualization of all the points connected
                                           // in the order they were generated.
                                           // Asking to draw line topology on a tri or quad patch will do this


    // The structures below define the data that is derived given input TessFactors and which
    // is used by point generation and connectivity generation steps (each of which are independent)
    typedef struct PROCESSED_TESS_FACTORS_ISOLINE
    {
        TESSELLATOR_PARITY lineDensityParity;
        TESSELLATOR_PARITY lineDetailParity;
        TESS_FACTOR_CONTEXT lineDensityTessFactorCtx;
        TESS_FACTOR_CONTEXT lineDetailTessFactorCtx;
        bool bPatchCulled;
        int numPointsPerLine;
        int numLines;
    } PROCESSED_TESS_FACTORS_ISOLINE;
    typedef struct PROCESSED_TESS_FACTORS_TRI
    {
        FXP outsideTessFactor[TRI_EDGES];
        FXP insideTessFactor;
        TESSELLATOR_PARITY outsideTessFactorParity[TRI_EDGES];
        TESSELLATOR_PARITY insideTessFactorParity;
        TESS_FACTOR_CONTEXT outsideTessFactorCtx[TRI_EDGES];
        TESS_FACTOR_CONTEXT insideTessFactorCtx;
        bool bJustDoMinimumTessFactor;
        bool bPatchCulled;
        // Stuff below is just specific to the traversal order
        // this code happens to use to generate points/lines
        int numPointsForOutsideEdge[TRI_EDGES];
        int numPointsForInsideTessFactor;
        int insideEdgePointBaseOffset;
    } PROCESSED_TESS_FACTORS_TRI;
    typedef struct PROCESSED_TESS_FACTORS_QUAD
    {
        FXP outsideTessFactor[QUAD_EDGES];
        FXP insideTessFactor[QUAD_AXES];
        TESSELLATOR_PARITY outsideTessFactorParity[QUAD_EDGES];
        TESSELLATOR_PARITY insideTessFactorParity[QUAD_AXES];
        TESS_FACTOR_CONTEXT outsideTessFactorCtx[QUAD_EDGES];
        TESS_FACTOR_CONTEXT insideTessFactorCtx[QUAD_AXES];
        bool bJustDoMinimumTessFactor;
        bool bPatchCulled;
        // Stuff below is just specific to the traversal order
        // this code happens to use to generate points/lines
        int numPointsForOutsideEdge[QUAD_EDGES];
        int numPointsForInsideTessFactor[QUAD_AXES];
        int insideEdgePointBaseOffset;
    } PROCESSED_TESS_FACTORS_QUAD;

    // These are the workhorse functions for tessellation:
    // (1) Process input TessFactors
    // (2) Generate points
    // (3) Generate connectivity (can be done in parallel to (2))
    void IsoLineProcessTessFactors( float TessFactor_V_LineDensity, float TessFactor_U_LineDetail, PROCESSED_TESS_FACTORS_ISOLINE& processedTessFactors );
    void IsoLineGeneratePoints( const PROCESSED_TESS_FACTORS_ISOLINE& processedTessFactors );
    void IsoLineGenerateConnectivity( const PROCESSED_TESS_FACTORS_ISOLINE& processedTessFactors );
    void TriProcessTessFactors( float tessFactor_Ueq0, float TessFactor_Veq0, float TessFactor_Weq0, float insideTessFactor, PROCESSED_TESS_FACTORS_TRI& processedTessFactors );
    void TriGeneratePoints( const PROCESSED_TESS_FACTORS_TRI& processedTessFactors );
    void TriGenerateConnectivity( const PROCESSED_TESS_FACTORS_TRI& processedTessFactors );
    void QuadProcessTessFactors( float tessFactor_Ueq0, float tessFactor_Veq0, float tessFactor_Ueq1, float tessFactor_Veq1,
                               float insideTessFactor_U, float insideTessFactor_V, PROCESSED_TESS_FACTORS_QUAD& processedTessFactors );
    void QuadGeneratePoints( const PROCESSED_TESS_FACTORS_QUAD& processedTessFactors );
    void QuadGenerateConnectivity( const PROCESSED_TESS_FACTORS_QUAD& processedTessFactors );

    // Stitching
    // ---------
    // Given pointers to the beginning of 2 parallel rows of points, and TessFactors for each, stitch them.
    // The assumption is the stitch is symmetric.
    void StitchTransition(int baseIndexOffset, int insideEdgePointBaseOffset, int insideNumHalfTessFactorPoints,
                                               TESSELLATOR_PARITY insideEdgeTessFactorParity,
                                               int outsideEdgePointBaseOffset, int outsideNumHalfTessFactorPoints,
                                               TESSELLATOR_PARITY outsideEdgeTessFactorParity );
    // The interior can just use a simpler stitch.
    enum DIAGONALS
    {
        DIAGONALS_INSIDE_TO_OUTSIDE,
        DIAGONALS_INSIDE_TO_OUTSIDE_EXCEPT_MIDDLE,
        DIAGONALS_MIRRORED
    };

    void StitchRegular(bool bTrapezoid, DIAGONALS diagonals, int baseIndexOffset, int numInsideEdgePoints,
                                        int insideEdgePointBaseOffset, int outsideEdgePointBaseOffset);

//---------------------------------------------------------------------------------------------------------------------------------
    // Index Patching
    // --------------
    // The code below patches index values produces during triangulation, so triangulation doesn't have to know
    // where points should go.  I happened to never produce duplicate vertices, but the patching would
    // be simpler if some duplicate vertices were introduced in practice.  During point rendering mode however,
    // it is not permitted for duplicate points to show up.

    // Since the points are generated in concentric rings, most of the time, the point locations are
    // sequentially increasing in memory for each side of a ring, which the stitch can take advantage of.
    // However, there are exceptions where the points are not sequentially increasing, such as
    // the 4th row in a given ring, where the last point on the outside of each row is actually the beginning
    // point.
    // So we let the stitching code think it sees sequential vertices, and when it emits a vertex index,
    // we patch it to be the real location.
    int  PatchIndexValue(int index);
    typedef struct INDEX_PATCH_CONTEXT
    {
        int insidePointIndexDeltaToRealValue;
        int insidePointIndexBadValue;
        int insidePointIndexReplacementValue;
        int outsidePointIndexPatchBase;
        int outsidePointIndexDeltaToRealValue;
        int outsidePointIndexBadValue;
        int outsidePointIndexReplacementValue;
    } INDEX_PATCH_CONTEXT;
    void SetUsingPatchedIndices(bool bUsingPatchedIndices) {m_bUsingPatchedIndices = bUsingPatchedIndices;}

    // A second index patch we have to do handles the leftover strip of quads in the middle of an odd quad patch after
    // finishing all the concentric rings.
    // This also handles the leftover strip of points in the middle of an even quad
    // patch, when stitching the row of triangles up the left side (V major quad) or bottom (U major quad) of the
    // inner ring
    typedef struct INDEX_PATCH_CONTEXT2
    {
        int baseIndexToInvert;
        int indexInversionEndPoint;
        int cornerCaseBadValue;
        int cornerCaseReplacementValue;
    } INDEX_PATCH_CONTEXT2;
    void SetUsingPatchedIndices2(bool bUsingPatchedIndices) {m_bUsingPatchedIndices2 = bUsingPatchedIndices;}
    bool                                 m_bUsingPatchedIndices;
    bool                                 m_bUsingPatchedIndices2;
    INDEX_PATCH_CONTEXT                  m_IndexPatchContext;
    INDEX_PATCH_CONTEXT2                 m_IndexPatchContext2;

};

//=================================================================================================================================
// CHLSLTessellator: D3D11 Tessellation HLSL Tessellator Interface
// Demonstrates TessFactor preconditioning code auto-generated by HLSL.  Subject to change, but this
// just represents the effect of shader code the HLSL compiler will generate in the Hull Shader,
// so it does not affect hardware design at all.
//=================================================================================================================================
class CHLSLTessellator : public CHWTessellator
{
public:
    void Init( D3D11_TESSELLATOR_PARTITIONING         partitioning,
               D3D11_TESSELLATOR_REDUCTION            insideTessFactorReduction,
               D3D11_TESSELLATOR_QUAD_REDUCTION_AXIS  quadInsideTessFactorReductionAxis,
               D3D11_TESSELLATOR_OUTPUT_PRIMITIVE     outputPrimitive);

    void TessellateIsoLineDomain( float TessFactor_V_LineDensity,
                                  float TessFactor_U_LineDetail );

    void TessellateTriDomain( float tessFactor_Ueq0,
                              float TessFactor_Veq0,
                              float TessFactor_Weq0,
                              float insideTessFactorScale /*[0..1]*/ );

    void TessellateQuadDomain( float TessFactorUeq0,
                               float TessFactorVeq0,
                               float TessFactorUeq1,
                               float TessFactorVeq1,
                               float insideTessFactorScaleU /*[0..1]*/,
                               float insideTessFactorScaleV /*[0..1]*/ );

    int GetPointCount() {return CHWTessellator::GetPointCount();};
    int GetIndexCount() {return CHWTessellator::GetIndexCount();}

    DOMAIN_POINT* GetPoints() {return CHWTessellator::GetPoints();} // Get CHLSLTessellator owned pointer to vertices (UV values).
                               // Pointer is fixed for lifetime of CHLSLTessellator object.
    int* GetIndices() {return CHWTessellator::GetIndices();}         // Get CHLSLTessellator owned pointer to vertex indices.
                               // Pointer is fixed for lifetime of CHLSLTessellator object.

    // Retrieve TessFactors actually used by the "hardware"
    // This includes clamping to valid range, and more interestingly
    // if integer or pow2 partitioning is being done, the rounded TessFactors can be retrieved.
    // Getting the rounded TessFactors can be useful for geomorphing of displacement maps.
    float GetIsoLineDensityTessFactor() {return m_LastComputedTessFactors[0];}
    float GetIsoLineDetailTessFactor() {return m_LastComputedTessFactors[1];}
    float GetTriUeq0TessFactor() {return m_LastComputedTessFactors[0];}
    float GetTriVeq0TessFactor() {return m_LastComputedTessFactors[1];}
    float GetTriWeq0TessFactor() {return m_LastComputedTessFactors[2];}
    float GetTriInsideTessFactor() {return m_LastComputedTessFactors[3];}
    float GetQuadUeq0TessFactor() {return m_LastComputedTessFactors[0];}
    float GetQuadVeq0TessFactor() {return m_LastComputedTessFactors[1];}
    float GetQuadUeq1TessFactor() {return m_LastComputedTessFactors[2];}
    float GetQuadVeq1TessFactor() {return m_LastComputedTessFactors[3];}
    float GetQuadInsideUTessFactor() {return m_LastComputedTessFactors[4];}
    float GetQuadInsideVTessFactor() {return m_LastComputedTessFactors[5];}
    float GetUnRoundedIsoLineDensityTessFactor() {return m_LastUnRoundedComputedTessFactors[0];}
    float GetUnRoundedIsoLineDetailTessFactor() {return m_LastUnRoundedComputedTessFactors[1];}
    float GetUnRoundedTriUeq0TessFactor() {return m_LastUnRoundedComputedTessFactors[0];}
    float GetUnRoundedTriVeq0TessFactor() {return m_LastUnRoundedComputedTessFactors[1];}
    float GetUnRoundedTriWeq0TessFactor() {return m_LastUnRoundedComputedTessFactors[2];}
    float GetUnRoundedTriInsideTessFactor() {return m_LastUnRoundedComputedTessFactors[3];}
    float GetUnRoundedQuadUeq0TessFactor() {return m_LastUnRoundedComputedTessFactors[0];}
    float GetUnRoundedQuadVeq0TessFactor() {return m_LastUnRoundedComputedTessFactors[1];}
    float GetUnRoundedQuadUeq1TessFactor() {return m_LastUnRoundedComputedTessFactors[2];}
    float GetUnRoundedQuadVeq1TessFactor() {return m_LastUnRoundedComputedTessFactors[3];}
    float GetUnRoundedQuadInsideUTessFactor() {return m_LastUnRoundedComputedTessFactors[4];}
    float GetUnRoundedQuadInsideVTessFactor() {return m_LastUnRoundedComputedTessFactors[5];}

    CHLSLTessellator();
//---------------------------------------------------------------------------------------------------------------------------------
private:
    TESSELLATOR_PARITY                   m_originalParity; // user chosen parity
    TESSELLATOR_PARITY                   m_parity; // current parity: if allowing mix of even/odd during discrete
                                                   // tessellation, this can vary from the user defined parity
    D3D11_TESSELLATOR_PARTITIONING       m_originalPartitioning; // user chosen partitioning
    D3D11_TESSELLATOR_PARTITIONING       m_partitioning; // current partitioning.  IsoLines overrides for line density
    D3D11_TESSELLATOR_OUTPUT_PRIMITIVE   m_outputPrimitive;
    D3D11_TESSELLATOR_REDUCTION          m_insideTessFactorReduction;
    D3D11_TESSELLATOR_QUAD_REDUCTION_AXIS m_quadInsideTessFactorReductionAxis;
    float                                m_LastComputedTessFactors[6]; // TessFactors used for last tessellation
    float                                m_LastUnRoundedComputedTessFactors[6]; // TessFactors used for last tessellation (before they were rounded)
    bool IntegerPartitioning() {return (m_partitioning == D3D11_TESSELLATOR_PARTITIONING_INTEGER) ? true : false;}
    bool Pow2Partitioning() {return (m_partitioning == D3D11_TESSELLATOR_PARTITIONING_POW2)? true : false;}
    void ClampTessFactor(float& TessFactor);
    void RoundUpTessFactor(float& TessFactor);
    void CleanupFloatTessFactor(float& input); // clamp float to [1.0f... +INF] (incl NaN->1.0f)
    void ClampFloatTessFactorScale(float& input); // clamp float to [0.0f... +INF] (incl NaN->0.0f)

    // Tessellation parity control
    bool Odd() {return (m_parity == TESSELLATOR_PARITY_ODD) ? true : false;}
    void SetTessellationParity(TESSELLATOR_PARITY parity) {m_parity = parity;}

    // Tesselation Partitioning control
    void RestorePartitioning() {m_partitioning = m_originalPartitioning;};
    void OverridePartitioning(D3D11_TESSELLATOR_PARTITIONING partitioning) {m_partitioning = partitioning;} //isoline uses this for density

    void IsoLineHLSLProcessTessFactors( float TessFactor_V_LineDensity, float TessFactor_U_LineDetail );
    void TriHLSLProcessTessFactors( float tessFactor_Ueq0, float TessFactor_Veq0, float TessFactor_Weq0, float insideTessFactor );
    void QuadHLSLProcessTessFactors( float TessFactor_Ueq0, float TessFactor_Veq0, float TessFactor_Ueq1, float TessFactor_Veq1,
                               float insideTessFactor_U, float insideTessFactor_V );

};