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//============ Copyright (c) Valve Corporation, All rights reserved. ============
//
// Utility functions for polygon simplification / convex decomposition.
//
//===============================================================================
#ifndef POLYGON_H
#define POLYGON_H
#if defined( COMPILER_MSVC )
#pragma once
#endif
#include "utlvector.h"
//-----------------------------------------------------------------------------
// NOTE: Polygons are assumed to be wound clockwise unless otherwise noted.
// Holes in polygons wind counter-clockwise.
//-----------------------------------------------------------------------------
static const float POINT_IN_POLYGON_EPSILON = 0.01f;
//-----------------------------------------------------------------------------
// Simplifies a polygon by removing points such that the area will not
// decrease by more than the specified amount (area increases are not
// allowed).
// With a low max deviation, this will perfectly remove all colinear points.
//-----------------------------------------------------------------------------
void SimplifyPolygon( CUtlVector< Vector > *pPoints, const Vector &vNormal, float flMaxDeviation );
//-----------------------------------------------------------------------------
// Simplifies a polygon using quadric error metrics.
//-----------------------------------------------------------------------------
void SimplifyPolygonQEM( CUtlVector< Vector > *pPoints, const Vector &vNormal, float flMaximumSquaredError, bool bUseOptimalPointPlacement );
//-----------------------------------------------------------------------------
// Returns whether a vertex of a polygon (v1) is concave, given its normal
// and previous & next vertices (v0 and v2, respectively).
//-----------------------------------------------------------------------------
bool IsConcave( const Vector &v0, const Vector &v1, const Vector &v2, const Vector &vNormal );
//-----------------------------------------------------------------------------
// Returns whether a vertex (points[nVertex]) of a polygon is
// concave, given the polygon's vertices, and its normal.
//-----------------------------------------------------------------------------
bool IsConcave( const Vector *pPolygonPoints, int nPointCount, int nVertex, const Vector &vNormal );
//-----------------------------------------------------------------------------
// Returns whether a polygon is concave.
//-----------------------------------------------------------------------------
bool IsConcave( const Vector *pPolygonPoints, int nPointCount, const Vector &vNormal );
//-----------------------------------------------------------------------------
// Given a set of points (i.e. vertex buffer), this represents an ordered
// subset of points which comprise a polygon (i.e. index buffer).
//-----------------------------------------------------------------------------
struct SubPolygon_t{ CUtlVector< int > m_Indices; int GetVertexIndex( int i ) const { i = i % m_Indices.Count(); if ( i < 0 ) { i += m_Indices.Count(); } return m_Indices[i]; }
static const Vector &GetPoint( const Vector *pPolygonPoints, int nPointCount, int nVertex ) { nVertex = nVertex % nPointCount; if ( nVertex < 0 ) { nVertex += nPointCount; } return pPolygonPoints[nVertex]; }
static const Vector &GetPoint( const CUtlVector< Vector > &originalPoints, int nVertex ) { return GetPoint( originalPoints.Base(), originalPoints.Count(), nVertex ); }};
//-----------------------------------------------------------------------------
// Attempts to strip off one convex region from a concave/convex polygon.
//-----------------------------------------------------------------------------
void DecomposePolygon_Step( const CUtlVector< Vector > &polygonPoints, const Vector &vNormal, CUtlVector< SubPolygon_t > *pHoles, SubPolygon_t *pNewPartition, SubPolygon_t *pRemainingPolygon, int *pFirstIndex );
//-----------------------------------------------------------------------------
// Decomposes a polygon into one or more convex, non-overlapping parts.
//-----------------------------------------------------------------------------
void DecomposePolygon( const CUtlVector< Vector > &polygonPoints, const Vector &vNormal, SubPolygon_t *pOriginalPolygon, CUtlVector< SubPolygon_t > *pHoles, CUtlVector< SubPolygon_t > *pPartitions );
//-----------------------------------------------------------------------------
// Is a point in the prism formed by extruding the polygon?
// If so, what is its height above/below the plane of the polygon?
//-----------------------------------------------------------------------------
bool IsPointInPolygonPrism( const Vector *pPolygonPoints, int nPointCount, const Vector &vPoint, float flThreshold = 0.0f, float *pHeight = NULL );
#endif // POLYGON_H
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