/* -------------------------------------------------------------------------------

   Copyright (C) 1999-2007 id Software, Inc. and contributors.
   For a list of contributors, see the accompanying CONTRIBUTORS file.

   This file is part of GtkRadiant.

   GtkRadiant is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   GtkRadiant is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GtkRadiant; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

   ----------------------------------------------------------------------------------

   This code has been altered significantly from its original form, to support
   several games based on the Quake III Arena engine, in the form of "Q3Map2."

   ------------------------------------------------------------------------------- */



/* dependencies */
#include "q3map2.h"



/*
   LerpDrawVert()
   returns an 50/50 interpolated vert
 */

bspDrawVert_t LerpDrawVert( const bspDrawVert_t& a, const bspDrawVert_t& b ){
	bspDrawVert_t out;

	out.xyz = vector3_mid( a.xyz, b.xyz );
	out.st = vector2_mid( a.st, b.st );

	for ( int k = 0; k < MAX_LIGHTMAPS; ++k )
	{
		out.lightmap[ k ] = vector2_mid( a.lightmap[ k ], b.lightmap[ k ] );
		for( int i = 0; i < 4; ++i )
			out.color[ k ][ i ] = ( a.color[ k ][ i ] + b.color[ k ][ i ] ) >> 1;
	}

	/* ydnar: added normal interpolation */
	out.normal = a.normal + b.normal;

	/* if the interpolant created a bogus normal, just copy the normal from a */
	if ( VectorNormalize( out.normal ) == 0 ) {
		out.normal = a.normal;
	}

	return out;
}



/*
   LerpDrawVertAmount()
   returns a biased interpolated vert
 */

void LerpDrawVertAmount( const bspDrawVert_t& a, const bspDrawVert_t& b, float amount, bspDrawVert_t& out ){

	out.xyz = a.xyz + ( b.xyz - a.xyz ) * amount;

	out.st = a.st + ( b.st - a.st ) * amount;

	for ( int k = 0; k < MAX_LIGHTMAPS; ++k )
	{
		out.lightmap[ k ] = a.lightmap[ k ] + ( b.lightmap[ k ] - a.lightmap[ k ] ) * amount;
		for( int i = 0; i < 4; ++i )
			out.color[ k ][ i ] = a.color[ k ][ i ] + amount * ( b.color[ k ][ i ] - a.color[ k ][ i ] );
	}

	out.normal = a.normal + ( b.normal - a.normal ) * amount;

	/* if the interpolant created a bogus normal, just copy the normal from a */
	if ( VectorNormalize( out.normal ) == 0 ) {
		out.normal = a.normal;
	}
}


void PrintMesh( const mesh_t& m ) {
	for ( int i = 0; i < m.height; ++i ) {
		for ( int j = 0; j < m.width; ++j ) {
			Sys_Printf( "(%5.2f %5.2f %5.2f) "
			            , m[i][j].xyz[0]
			            , m[i][j].xyz[1]
			            , m[i][j].xyz[2] );
		}
		Sys_Printf( "\n" );
	}
	Sys_Printf( "\n" );
}


/*
   TransposeMesh()
   returns a transposed copy of the mesh, freeing the original
 */

void TransposeMesh( mesh_t& m ) {
	mesh_t out( m.height, m.width ); // swap width/height

	for ( int h = 0; h < m.height; ++h )
		for ( int w = 0; w < m.width; ++w )
			out[ w ][ h ] = m[ h ][ w ];

	m = std::move( out );
}
/* 90` clockwise */
void RotateMesh( mesh_t& m ) {
	mesh_t out( m.height, m.width ); // swap width/height

	for ( int h = 0; h < m.height; ++h )
		for ( int w = 0; w < m.width; ++w )
			out[ w ][ m.height - 1 - h ] = m[ h ][ w ];

	m = std::move( out );
}

void InvertMesh( mesh_t& m ) {
	for ( int h = 0; h < m.height; ++h )
		for ( int w = 0; w < m.width / 2; ++w )
			std::swap(
				m[ h ][ w ],
				m[ h ][ m.width - 1 - w ]
			);
}

/*
   =================
   MakeMeshNormals

   =================
 */
void MakeMeshNormals( mesh_t& in ){
	int i, j, k, dist;
	int count;
	int x, y;
	Vector3 around[8];
	bool good[8];
	bool wrapWidth, wrapHeight;
	int neighbors[8][2] =
	{
		{ 0, 1 }, { 1, 1 }, { 1, 0 }, { 1,-1 },
		{ 0,-1 }, {-1,-1 }, {-1, 0 }, {-1, 1 }
	};


	wrapWidth = false;
	for ( i = 0; i < in.height; ++i ) {
		if ( vector3_length( in[i][0].xyz - in[i][in.width - 1].xyz ) > 1 ) {
			break;
		}
	}
	if ( i == in.height ) {
		wrapWidth = true;
	}

	wrapHeight = false;
	for ( i = 0; i < in.width; ++i ) {
		if ( vector3_length( in[0][i].xyz - in[in.height - 1][i].xyz ) > 1 ) {
			break;
		}
	}
	if ( i == in.width ) {
		wrapHeight = true;
	}


	for ( i = 0; i < in.width; ++i ) {
		for ( j = 0; j < in.height; ++j ) {
			count = 0;
			bspDrawVert_t& dv = in[j][i];
			const Vector3 base( dv.xyz );
			for ( k = 0; k < 8; ++k ) {
				around[k].set( 0 );
				good[k] = false;

				for ( dist = 1; dist <= 3; ++dist ) {
					x = i + neighbors[k][0] * dist;
					y = j + neighbors[k][1] * dist;
					if ( wrapWidth ) {
						if ( x < 0 ) {
							x = in.width - 1 + x;
						}
						else if ( x >= in.width ) {
							x = 1 + x - in.width;
						}
					}
					if ( wrapHeight ) {
						if ( y < 0 ) {
							y = in.height - 1 + y;
						}
						else if ( y >= in.height ) {
							y = 1 + y - in.height;
						}
					}

					if ( x < 0 || x >= in.width || y < 0 || y >= in.height ) {
						break;                  // edge of patch
					}
					Vector3 temp = in[y][x].xyz - base;
					if ( VectorNormalize( temp ) == 0 ) {
						continue;               // degenerate edge, get more dist
					}
					else {
						good[k] = true;
						around[k] = temp;
						break;                  // good edge
					}
				}
			}

			Vector3 sum( 0 );
			for ( k = 0; k < 8; ++k ) {
				if ( !good[k] || !good[( k + 1 ) & 7] ) {
					continue;   // didn't get two points
				}
				Vector3 normal = vector3_cross( around[( k + 1 ) & 7], around[k] );
				if ( VectorNormalize( normal ) == 0 ) {
					continue;
				}
				sum += normal;
				count++;
			}
			if ( count == 0 ) {
//Sys_Printf( "bad normal\n" );
				count = 1;
			}
			dv.normal = VectorNormalized( sum );
		}
	}
}

/*
   PutMeshOnCurve()
   drops the aproximating points onto the curve
 */

void PutMeshOnCurve( mesh_t& in ) {
	const auto lerp3 = []( const bspDrawVert_t& prev, bspDrawVert_t& mid, const bspDrawVert_t& next ){
		mid.xyz = ( prev.xyz + mid.xyz * 2 + next.xyz ) * .25;
		/* ydnar: interpolating st coords */
		mid.st = ( prev.st + mid.st * 2 + next.st ) * .25;
		for ( int m = 0; m < MAX_LIGHTMAPS; ++m )
			mid.lightmap[ m ] = ( prev.lightmap[ m ] + mid.lightmap[ m ] * 2 + next.lightmap[ m ] ) * .25;
	};
	// put all the aproximating points on the curve
	for ( int i = 0; i < in.width; ++i )
		for ( int j = 1; j < in.height; j += 2 )
			lerp3( in[ j - 1 ][ i ],
			       in[ j + 0 ][ i ],
			       in[ j + 1 ][ i ] );

	for ( int j = 0; j < in.height; ++j )
		for ( int i = 1; i < in.width; i += 2 )
			lerp3( in[ j ][ i - 1 ],
			       in[ j ][ i + 0 ],
			       in[ j ][ i + 1 ] );
}


/*
   =================
   SubdivideMesh

   =================
 */
mesh_t SubdivideMesh( const mesh_view_t in, float maxError, float minLength ){
	bspDrawVert_t expand[MAX_EXPANDED_AXIS][MAX_EXPANDED_AXIS];
	int width = in.width;
	int height = in.height;

	/* copy each row */
	for ( int h = 0; h < in.height; ++h )
		std::copy_n( in[h], in.width, expand[h] );

	// horizontal subdivisions
	for ( int i, j = 0; j + 2 < width; j += 2 ) {
		// check subdivided midpoints against control points
		for ( i = 0; i < height; ++i ) {
			const Vector3 prevxyz = expand[i][j + 1].xyz - expand[i][j].xyz;
			const Vector3 nextxyz = expand[i][j + 2].xyz - expand[i][j + 1].xyz;
			const Vector3 midxyz = ( expand[i][j].xyz + expand[i][j + 1].xyz * 2 + expand[i][j + 2].xyz ) * 0.25;

			// if the span length is too long, force a subdivision
			if ( vector3_length( prevxyz ) > minLength
			  || vector3_length( nextxyz ) > minLength ) {
				break;
			}

			// see if this midpoint is off far enough to subdivide
			if ( vector3_length( expand[i][j + 1].xyz - midxyz ) > maxError ) {
				break;
			}
		}

		if ( width + 2 >= MAX_EXPANDED_AXIS ) {
			break;  // can't subdivide any more
		}

		if ( i == height ) {
			continue;   // didn't need subdivision
		}

		// insert two columns and replace the peak
		width += 2;

		for ( i = 0; i < height; ++i ) {
			for ( int k = width - 1; k > j + 3; --k ) {
				expand[i][k] = expand[i][k - 2];
			}
			expand[i][j + 3] = LerpDrawVert( expand[i][j + 1], expand[i][j + 2] );
			expand[i][j + 1] = LerpDrawVert( expand[i][j + 0], expand[i][j + 1] );
			expand[i][j + 2] = LerpDrawVert( expand[i][j + 1], expand[i][j + 3] );
		}

		// back up and recheck this set again, it may need more subdivision
		j -= 2;
	}

	// vertical subdivisions
	for ( int i, j = 0; j + 2 < height; j += 2 ) {
		// check subdivided midpoints against control points
		for ( i = 0; i < width; ++i ) {
			const Vector3 prevxyz = expand[j + 1][i].xyz - expand[j][i].xyz;
			const Vector3 nextxyz = expand[j + 2][i].xyz - expand[j + 1][i].xyz;
			const Vector3 midxyz = ( expand[j][i].xyz + expand[j + 1][i].xyz * 2 + expand[j + 2][i].xyz ) * 0.25;

			// if the span length is too long, force a subdivision
			if ( vector3_length( prevxyz ) > minLength
			  || vector3_length( nextxyz ) > minLength ) {
				break;
			}
			// see if this midpoint is off far enough to subdivide
			if ( vector3_length( expand[j + 1][i].xyz - midxyz ) > maxError ) {
				break;
			}
		}

		if ( height + 2 >= MAX_EXPANDED_AXIS ) {
			break;  // can't subdivide any more
		}

		if ( i == width ) {
			continue;   // didn't need subdivision
		}

		// insert two columns and replace the peak
		height += 2;

		for ( i = 0; i < width; ++i ) {
			for ( int k = height - 1; k > j + 3; --k ) {
				expand[k][i] = expand[k - 2][i];
			}
			expand[j + 3][i] = LerpDrawVert( expand[j + 1][i], expand[j + 2][i] );
			expand[j + 1][i] = LerpDrawVert( expand[j + 0][i], expand[j + 1][i] );
			expand[j + 2][i] = LerpDrawVert( expand[j + 1][i], expand[j + 3][i] );
		}

		// back up and recheck this set again, it may need more subdivision
		j -= 2;
	}

	// collapse the verts

	for ( int i = 1; i < height; ++i ) {
		memmove( expand[0] + width * i, expand[i], width * sizeof( bspDrawVert_t ) );
	}

	return mesh_t( width, height, expand[0] );
}



/*
   IterationsForCurve() - ydnar
   given a curve of a certain length, return the number of subdivision iterations
   note: this is affected by subdivision amount
 */

int IterationsForCurve( float len, int subdivisions ){
	int iterations, facets;


	/* calculate the number of subdivisions */
	for ( iterations = 0; iterations < 3; ++iterations )
	{
		facets = subdivisions * 16 * pow( 2, iterations );
		if ( facets >= len ) {
			break;
		}
	}

	/* return to caller */
	return iterations;
}


/*
   SubdivideMesh2() - ydnar
   subdivides each mesh quad a specified number of times
 */

mesh_t SubdivideMesh2( const mesh_view_t in, int iterations ){
	bspDrawVert_t expand[ MAX_EXPANDED_AXIS ][ MAX_EXPANDED_AXIS ];
	int width = in.width;
	int height = in.height;

	/* copy each row */
	for ( int h = 0; h < in.height; ++h )
		std::copy_n( in[h], in.width, expand[h] );

	/* keep chopping */
	for ( ; iterations > 0; --iterations )
	{
		/* horizontal subdivisions */
		for ( int j = 0; j + 2 < width; j += 4 )
		{
			/* check size limit */
			if ( width + 2 >= MAX_EXPANDED_AXIS ) {
				break;
			}

			/* insert two columns and replace the peak */
			width += 2;
			for ( int i = 0; i < height; ++i )
			{
				for ( int k = width - 1; k > j + 3; --k )
					expand [ i ][ k ] = expand[ i ][ k - 2 ];

				expand[ i ][ j + 3 ] = LerpDrawVert( expand[ i ][ j + 1 ], expand[ i ][ j + 2 ] );
				expand[ i ][ j + 1 ] = LerpDrawVert( expand[ i ][ j + 0 ], expand[ i ][ j + 1 ] );
				expand[ i ][ j + 2 ] = LerpDrawVert( expand[ i ][ j + 1 ], expand[ i ][ j + 3 ] );
			}
		}

		/* vertical subdivisions */
		for ( int j = 0; j + 2 < height; j += 4 )
		{
			/* check size limit */
			if ( height + 2 >= MAX_EXPANDED_AXIS ) {
				break;
			}

			/* insert two columns and replace the peak */
			height += 2;
			for ( int i = 0; i < width; ++i )
			{
				for ( int k = height - 1; k > j + 3; --k )
					expand[ k ][ i ] = expand[ k - 2 ][ i ];

				expand[ j + 3 ][ i ] = LerpDrawVert( expand[ j + 1 ][ i ], expand[ j + 2 ][ i ] );
				expand[ j + 1 ][ i ] = LerpDrawVert( expand[ j + 0 ][ i ], expand[ j + 1 ][ i ] );
				expand[ j + 2 ][ i ] = LerpDrawVert( expand[ j + 1 ][ i ], expand[ j + 3 ][ i ] );
			}
		}
	}

	/* collapse the verts */
	for ( int i = 1; i < height; ++i )
		memmove( expand[0] + width * i, expand[ i ], width * sizeof( bspDrawVert_t ) );

	/* return to sender */
	return mesh_t( width, height, expand[0] );
}







/*
   ================
   ProjectPointOntoVector
   ================
 */
inline Vector3 ProjectPointOntoVector( const Vector3& point, const Vector3& vStart, const Vector3& vEnd ){
	const Vector3 pVec = point - vStart;
	const Vector3 vec = VectorNormalized( vEnd - vStart );
	// project onto the directional vector for this segment
	return ( vStart + vec * vector3_dot( pVec, vec ) );
}

/*
   ================
   RemoveLinearMeshColumsRows
   ================
 */
mesh_t RemoveLinearMeshColumnsRows( const mesh_t& in ) {
	bspDrawVert_t expand[MAX_EXPANDED_AXIS][MAX_EXPANDED_AXIS];
	int width = in.width;
	int height = in.height;

	/* copy each row */
	for ( int h = 0; h < in.height; ++h )
		std::copy_n( in[h], in.width, expand[h] );

	for ( int j = 1; j < width - 1; ++j ) {
		double maxLength = 0;
		for ( int i = 0; i < height; ++i ) {
			value_maximize( maxLength, vector3_length( expand[i][j].xyz - ProjectPointOntoVector( expand[i][j].xyz, expand[i][j - 1].xyz, expand[i][j + 1].xyz ) ) );
		}
		if ( maxLength < 0.1 ) {
			width--;
			for ( int i = 0; i < height; ++i ) {
				for ( int k = j; k < width; ++k ) {
					expand[i][k] = expand[i][k + 1];
				}
			}
			j--;
		}
	}
	for ( int j = 1; j < height - 1; ++j ) {
		double maxLength = 0;
		for ( int i = 0; i < width; ++i ) {
			value_maximize( maxLength, vector3_length( expand[j][i].xyz - ProjectPointOntoVector( expand[j][i].xyz, expand[j - 1][i].xyz, expand[j + 1][i].xyz ) ) );
		}
		if ( maxLength < 0.1 ) {
			height--;
			for ( int i = 0; i < width; ++i ) {
				for ( int k = j; k < height; ++k ) {
					expand[k][i] = expand[k + 1][i];
				}
			}
			j--;
		}
	}
	// collapse the verts
	for ( int i = 1; i < height; ++i ) {
		memmove( expand[0] + width * i, expand[i], width * sizeof( bspDrawVert_t ) );
	}

	return mesh_t( width, height, expand[0] );
}


mesh_t TessellatedMesh( const mesh_view_t in, int iterations ){
	//%	mesh_t subdivided = SubdivideMesh( in, 8, 512 );
	mesh_t subdivided = SubdivideMesh2( in, iterations );

	/* fit it to the curve and remove colinear verts on rows/columns */
	PutMeshOnCurve( subdivided );
	mesh_t mesh = RemoveLinearMeshColumnsRows( subdivided );
	//% MakeMeshNormals( mesh );

	return mesh;
}


/*
   =================
   SubdivideMeshQuads
   =================
 */
static mesh_t SubdivideMeshQuads( const mesh_view_t in, float minLength, int maxsize, int *widthtable, int *heighttable ){
	int i, j, k, w, h, maxsubdivisions, subdivisions;
	bspDrawVert_t expand[MAX_EXPANDED_AXIS][MAX_EXPANDED_AXIS];
	int width = in.width;
	int height = in.height;

	/* copy each row */
	for ( int h = 0; h < in.height; ++h )
		std::copy_n( in[h], in.width, expand[h] );

	if ( maxsize > MAX_EXPANDED_AXIS ) {
		Error( "SubdivideMeshQuads: maxsize > MAX_EXPANDED_AXIS" );
	}

	// horizontal subdivisions

	maxsubdivisions = ( maxsize - in.width ) / ( in.width - 1 );

	for ( w = 0, j = 0; w < in.width - 1; ++w, j += subdivisions + 1 ) {
		double maxLength = 0;
		for ( i = 0; i < height; ++i ) {
			value_maximize( maxLength, vector3_length( expand[i][j + 1].xyz - expand[i][j].xyz ) );
		}

		subdivisions = std::min( (int) ( maxLength / minLength ), maxsubdivisions );

		widthtable[w] = subdivisions + 1;
		if ( subdivisions <= 0 ) {
			continue;
		}

		width += subdivisions;

		for ( i = 0; i < height; ++i ) {
			for ( k = width - 1; k > j + subdivisions; --k ) {
				expand[i][k] = expand[i][k - subdivisions];
			}
			for ( k = 1; k <= subdivisions; ++k )
			{
				const float amount = (float) k / ( subdivisions + 1 );
				LerpDrawVertAmount( expand[i][j], expand[i][j + subdivisions + 1], amount, expand[i][j + k] );
			}
		}
	}

	maxsubdivisions = ( maxsize - in.height ) / ( in.height - 1 );

	for ( h = 0, j = 0; h < in.height - 1; ++h, j += subdivisions + 1 ) {
		double maxLength = 0;
		for ( i = 0; i < width; ++i ) {
			value_maximize( maxLength, vector3_length( expand[j + 1][i].xyz - expand[j][i].xyz ) );
		}

		subdivisions = std::min( (int) ( maxLength / minLength ), maxsubdivisions );

		heighttable[h] = subdivisions + 1;
		if ( subdivisions <= 0 ) {
			continue;
		}

		height += subdivisions;

		for ( i = 0; i < width; ++i ) {
			for ( k = height - 1; k > j + subdivisions; --k ) {
				expand[k][i] = expand[k - subdivisions][i];
			}
			for ( k = 1; k <= subdivisions; ++k )
			{
				const float amount = (float) k / ( subdivisions + 1 );
				LerpDrawVertAmount( expand[j][i], expand[j + subdivisions + 1][i], amount, expand[j + k][i] );
			}
		}
	}

	// collapse the verts
	for ( i = 1; i < height; ++i ) {
		memmove( expand[0] + width * i, expand[i], width * sizeof( bspDrawVert_t ) );
	}

	return mesh_t( width, height, expand[0] );
}