CWE-ou-minkata/Sources/Plasma/PubUtilLib/plScene/plOccTree.h

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*==LICENSE==*/

#ifndef plOccTree_inc
#define plOccTree_inc

#include "hsTemplates.h"
#include "hsGeometry3.h"

class plBoundsHierarchy;

class plOccPlane
{
public:
    hsVector3           fNormal;
    hsScalar            fDist;

};

class plOccPoly
{
public:
    enum {
        kEdgeClipped        = 0x1
    };

    plOccPlane                  fPlane;

    hsTArray<hsPoint3>          fVerts;
    hsTArray<uint8_t>             fEdgeFlags; // flag[i] => edge(fVerts[i], fVerts[(i+1)%n])
};

class plOccNode
{
protected:
    enum {
        kNone           = 0x0,
        kIsLeaf         = 0x1
    };
    enum {
        kAllIn          = 0x0,
        kAllOut         = 0x1,
        kSplit          = 0x2
    };

    uint32_t              fFlags;

    plOccPlane          fPolyPlane; // Plane of the poly we came from
    plOccPlane          fViewPlane; // Plane perp to view dir. 
    // For an interior node, ViewPlane is for the nearest (to view) point
    // on the poly. A bound closer than that will not be occluded by this
    // node or any nodes deeper in the tree.
    // For a leaf it's the farthest point on the poly. A bound inside this
    // plane OR the PolyPlane is occluded.

    plOccNode*      fInChild;
    
    plOccNode*      fOutChild;
};

class plOccTree
{
protected:

    enum {
        kNone           = 0x0,
        kNeedsBuild     = 0x1
    };

    uint8_t                   fFlags;

    // Temp pools for building our trees each frame.
    hsTArray<plOccPoly>     fPolyPool;
    hsTArray<plOccPoly>     fBasePolys;

    // The BSP used to add our polys front to back. This BSP is constant.
    plOccNode*          fBSP;

    // This current frame's view pos and occluder tree.
    plOccNode*          fRoot;
    hsPoint3            fViewPos;


    plOccNode*          IAddPolyRecur(plOccNode* n, plOccPoly* poly);

    void                ITrimPoly(plOccPlane& plane, plOccPoly* polyIn, plOccPoly*& polyIn, plOccPoly*& polyOut);

    plOccNode*          IBuildOccTree();

public:

    plOccTree() : fFlags(kNone), fBSP(nil), fRoot(nil) {}
    ~plOccTree() {}

    // We'll take in the view position (for sorting and building).
    // The view direction isn't necessary, but may be useful for
    // selecting a subset of occluders (like don't bother with ones parallel to the view dir).
    // What we really want is to pass in the viewport walls, or all the clip planes to initialize
    // the occtree, then occluders out of view are automatically pruned, and the single test
    // does the full view/portal/occluder test.
    void SetView(const hsPoint3& pos, const hsVector3& dir);


    // The algorithm is:
    //  if bnd is totally inside this node's plane
    //      recur bnd on inside child/leaf
    //  else if bnd is totaly outside this node's plane
    //      recur bnd on outside child
    //  else
    //      recur bnd's children on this node
    // 
    // There's two ways to output the visibility info
    //      1) Set a visible/invisible bit for each of the bnd leaves
    //      2) output a list of visible bnds.
    // The second is preferable, since leaves determined invisible by interior
    // node tests never get traversed. But if the rendering pipeline has needs
    // to traverse the drawable data in some other order (for depth or material
    // sorting for example), then the list of visible bnds needs to be translated
    // into the first option anyway.
    //
    // Notes on the vague algorithm:
    //  When recurring on the inside child, hitting a leaf checks against the source
    //      occluder poly, with the usual inside=hidden, outside=visible, split recurs
    //      the bnd's children on this leaf.
    //  Hitting a nil outside child == visible
    //  It's a double recursion, recurring first on the bnd hierarchy, and second on the occluder tree.
    //  Recursion stops when:
    //      1) A bnd is totally in or totally out of a leaf of the occluder tree
    //      2) A bnd is a leaf of the bnd hierarchy.
    // 
    void TestHeirarchy(plBoundsHierarchy* bnd);

    virtual void Read(hsStream* s, hsResMgr* mgr);
    virtual void Write(hsStream* s, hsResMgr* mgr);

    // Export only
    void                AddPoly(plOccPoly* poly);
    void                BuildBSP();
};

#endif // plOccTree_inc