/*
===========================================================================

Return to Castle Wolfenstein single player GPL Source Code
Copyright (C) 1999-2010 id Software LLC, a ZeniMax Media company. 

This file is part of the Return to Castle Wolfenstein single player GPL Source Code (RTCW SP Source Code).  

RTCW SP Source Code 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 3 of the License, or
(at your option) any later version.

RTCW SP Source Code 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 RTCW SP Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the RTCW SP Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the RTCW SP Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

===========================================================================
*/


#include "tr_local.h"

/*

This file does all of the processing necessary to turn a raw grid of points
read from the map file into a srfGridMesh_t ready for rendering.

The level of detail solution is direction independent, based only on subdivided
distance from the true curve.

Only a single entry point:

srfGridMesh_t *R_SubdividePatchToGrid( int width, int height,
								drawVert_t points[MAX_PATCH_SIZE*MAX_PATCH_SIZE] ) {

*/


/*
============
LerpDrawVert
============
*/
static void LerpDrawVert( drawVert_t *a, drawVert_t *b, drawVert_t *out ) {
	out->xyz[0] = 0.5f * ( a->xyz[0] + b->xyz[0] );
	out->xyz[1] = 0.5f * ( a->xyz[1] + b->xyz[1] );
	out->xyz[2] = 0.5f * ( a->xyz[2] + b->xyz[2] );

	out->st[0] = 0.5f * ( a->st[0] + b->st[0] );
	out->st[1] = 0.5f * ( a->st[1] + b->st[1] );

	out->lightmap[0] = 0.5f * ( a->lightmap[0] + b->lightmap[0] );
	out->lightmap[1] = 0.5f * ( a->lightmap[1] + b->lightmap[1] );

	out->color[0] = ( a->color[0] + b->color[0] ) >> 1;
	out->color[1] = ( a->color[1] + b->color[1] ) >> 1;
	out->color[2] = ( a->color[2] + b->color[2] ) >> 1;
	out->color[3] = ( a->color[3] + b->color[3] ) >> 1;
}

/*
============
Transpose
============
*/
static void Transpose( int width, int height, drawVert_t ctrl[MAX_GRID_SIZE][MAX_GRID_SIZE] ) {
	int i, j;
	drawVert_t temp;

	if ( width > height ) {
		for ( i = 0 ; i < height ; i++ ) {
			for ( j = i + 1 ; j < width ; j++ ) {
				if ( j < height ) {
					// swap the value
					temp = ctrl[j][i];
					ctrl[j][i] = ctrl[i][j];
					ctrl[i][j] = temp;
				} else {
					// just copy
					ctrl[j][i] = ctrl[i][j];
				}
			}
		}
	} else {
		for ( i = 0 ; i < width ; i++ ) {
			for ( j = i + 1 ; j < height ; j++ ) {
				if ( j < width ) {
					// swap the value
					temp = ctrl[i][j];
					ctrl[i][j] = ctrl[j][i];
					ctrl[j][i] = temp;
				} else {
					// just copy
					ctrl[i][j] = ctrl[j][i];
				}
			}
		}
	}

}


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

Handles all the complicated wrapping and degenerate cases
=================
*/
static void MakeMeshNormals( int width, int height, drawVert_t ctrl[MAX_GRID_SIZE][MAX_GRID_SIZE] ) {
	int i, j, k, dist;
	vec3_t normal;
	vec3_t sum;
	int count;
	vec3_t base;
	vec3_t delta;
	int x, y;
	drawVert_t  *dv;
	vec3_t around[8], temp;
	qboolean good[8];
	qboolean wrapWidth, wrapHeight;
	float len;
	static int neighbors[8][2] = {
		{0,1}, {1,1}, {1,0}, {1,-1}, {0,-1}, {-1,-1}, {-1,0}, {-1,1}
	};

	wrapWidth = qfalse;
	for ( i = 0 ; i < height ; i++ ) {
		VectorSubtract( ctrl[i][0].xyz, ctrl[i][width - 1].xyz, delta );
		len = VectorLengthSquared( delta );
		if ( len > 1.0 ) {
			break;
		}
	}
	if ( i == height ) {
		wrapWidth = qtrue;
	}

	wrapHeight = qfalse;
	for ( i = 0 ; i < width ; i++ ) {
		VectorSubtract( ctrl[0][i].xyz, ctrl[height - 1][i].xyz, delta );
		len = VectorLengthSquared( delta );
		if ( len > 1.0 ) {
			break;
		}
	}
	if ( i == width ) {
		wrapHeight = qtrue;
	}


	for ( i = 0 ; i < width ; i++ ) {
		for ( j = 0 ; j < height ; j++ ) {
			count = 0;
			dv = &ctrl[j][i];
			VectorCopy( dv->xyz, base );
			for ( k = 0 ; k < 8 ; k++ ) {
				VectorClear( around[k] );
				good[k] = qfalse;

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

					if ( x < 0 || x >= width || y < 0 || y >= height ) {
						break;                  // edge of patch
					}
					VectorSubtract( ctrl[y][x].xyz, base, temp );
					if ( VectorNormalize2( temp, temp ) == 0 ) {
						continue;               // degenerate edge, get more dist
					} else {
						good[k] = qtrue;
						VectorCopy( temp, around[k] );
						break;                  // good edge
					}
				}
			}

			VectorClear( sum );
			for ( k = 0 ; k < 8 ; k++ ) {
				if ( !good[k] || !good[( k + 1 ) & 7] ) {
					continue;   // didn't get two points
				}
				CrossProduct( around[( k + 1 ) & 7], around[k], normal );
				if ( VectorNormalize2( normal, normal ) == 0 ) {
					continue;
				}
				VectorAdd( normal, sum, sum );
				count++;
			}
			if ( count == 0 ) {
//printf("bad normal\n");
				count = 1;
			}
			VectorNormalize2( sum, dv->normal );
		}
	}
}

/*
============
InvertCtrl
============
*/
static void InvertCtrl( int width, int height, drawVert_t ctrl[MAX_GRID_SIZE][MAX_GRID_SIZE] ) {
	int i, j;
	drawVert_t temp;

	for ( i = 0 ; i < height ; i++ ) {
		for ( j = 0 ; j < width / 2 ; j++ ) {
			temp = ctrl[i][j];
			ctrl[i][j] = ctrl[i][width - 1 - j];
			ctrl[i][width - 1 - j] = temp;
		}
	}
}


/*
=================
InvertErrorTable
=================
*/
static void InvertErrorTable( float errorTable[2][MAX_GRID_SIZE], int width, int height ) {
	int i;
	float copy[2][MAX_GRID_SIZE];

	memcpy( copy, errorTable, sizeof( copy ) );

	for ( i = 0 ; i < width ; i++ ) {
		errorTable[1][i] = copy[0][i];  //[width-1-i];
	}

	for ( i = 0 ; i < height ; i++ ) {
		errorTable[0][i] = copy[1][height - 1 - i];
	}

}

/*
==================
PutPointsOnCurve
==================
*/
static void PutPointsOnCurve( drawVert_t ctrl[MAX_GRID_SIZE][MAX_GRID_SIZE],
							  int width, int height ) {
	int i, j;
	drawVert_t prev, next;

	for ( i = 0 ; i < width ; i++ ) {
		for ( j = 1 ; j < height ; j += 2 ) {
			LerpDrawVert( &ctrl[j][i], &ctrl[j + 1][i], &prev );
			LerpDrawVert( &ctrl[j][i], &ctrl[j - 1][i], &next );
			LerpDrawVert( &prev, &next, &ctrl[j][i] );
		}
	}


	for ( j = 0 ; j < height ; j++ ) {
		for ( i = 1 ; i < width ; i += 2 ) {
			LerpDrawVert( &ctrl[j][i], &ctrl[j][i + 1], &prev );
			LerpDrawVert( &ctrl[j][i], &ctrl[j][i - 1], &next );
			LerpDrawVert( &prev, &next, &ctrl[j][i] );
		}
	}
}


/*
=================
R_CreateSurfaceGridMesh
=================
*/
srfGridMesh_t *R_CreateSurfaceGridMesh( int width, int height,
										drawVert_t ctrl[MAX_GRID_SIZE][MAX_GRID_SIZE], float errorTable[2][MAX_GRID_SIZE] ) {
	int i, j, size;
	drawVert_t  *vert;
	vec3_t tmpVec;
	srfGridMesh_t *grid;

	// copy the results out to a grid
	size = ( width * height - 1 ) * sizeof( drawVert_t ) + sizeof( *grid );

#ifdef PATCH_STITCHING
	grid = malloc( size );
	Com_Memset( grid, 0, size );

	grid->widthLodError = malloc( width * 4 );
	memcpy( grid->widthLodError, errorTable[0], width * 4 );

	grid->heightLodError = malloc( height * 4 );
	memcpy( grid->heightLodError, errorTable[1], height * 4 );
#else
	grid = ri.Hunk_Alloc( size, h_low );
	memset( grid, 0, size );

	grid->widthLodError = ri.Hunk_Alloc( width * 4, h_low );
	memcpy( grid->widthLodError, errorTable[0], width * 4 );

	grid->heightLodError = ri.Hunk_Alloc( height * 4, h_low );
	memcpy( grid->heightLodError, errorTable[1], height * 4 );
#endif

	grid->width = width;
	grid->height = height;
	grid->surfaceType = SF_GRID;
	ClearBounds( grid->meshBounds[0], grid->meshBounds[1] );
	for ( i = 0 ; i < width ; i++ ) {
		for ( j = 0 ; j < height ; j++ ) {
			vert = &grid->verts[j * width + i];
			*vert = ctrl[j][i];
			AddPointToBounds( vert->xyz, grid->meshBounds[0], grid->meshBounds[1] );
		}
	}

	// compute local origin and bounds
	VectorAdd( grid->meshBounds[0], grid->meshBounds[1], grid->localOrigin );
	VectorScale( grid->localOrigin, 0.5f, grid->localOrigin );
	VectorSubtract( grid->meshBounds[0], grid->localOrigin, tmpVec );
	grid->meshRadius = VectorLength( tmpVec );

	VectorCopy( grid->localOrigin, grid->lodOrigin );
	grid->lodRadius = grid->meshRadius;
	//
	return grid;
}

/*
=================
R_FreeSurfaceGridMesh
=================
*/
void R_FreeSurfaceGridMesh( srfGridMesh_t *grid ) {
	free( grid->widthLodError );
	free( grid->heightLodError );
	free( grid );
}

/*
=================
R_SubdividePatchToGrid
=================
*/
srfGridMesh_t *R_SubdividePatchToGrid( int width, int height,
									   drawVert_t points[MAX_PATCH_SIZE*MAX_PATCH_SIZE] ) {
	int i, j, k, l;
	drawVert_t prev, next, mid;
	float len, maxLen;
	int dir;
	int t;
	MAC_STATIC drawVert_t ctrl[MAX_GRID_SIZE][MAX_GRID_SIZE];
	float errorTable[2][MAX_GRID_SIZE];

	for ( i = 0 ; i < width ; i++ ) {
		for ( j = 0 ; j < height ; j++ ) {
			ctrl[j][i] = points[j * width + i];
		}
	}

	for ( dir = 0 ; dir < 2 ; dir++ ) {

		for ( j = 0 ; j < MAX_GRID_SIZE ; j++ ) {
			errorTable[dir][j] = 0;
		}

		// horizontal subdivisions
		for ( j = 0 ; j + 2 < width ; j += 2 ) {
			// check subdivided midpoints against control points

			// FIXME: also check midpoints of adjacent patches against the control points
			// this would basically stitch all patches in the same LOD group together.

			maxLen = 0;
			for ( i = 0 ; i < height ; i++ ) {
				vec3_t midxyz;
				vec3_t dir;
				vec3_t projected;
				float d;

				// calculate the point on the curve
				for ( l = 0 ; l < 3 ; l++ ) {
					midxyz[l] = ( ctrl[i][j].xyz[l] + ctrl[i][j + 1].xyz[l] * 2
								  + ctrl[i][j + 2].xyz[l] ) * 0.25f;
				}

				// see how far off the line it is
				// using dist-from-line will not account for internal
				// texture warping, but it gives a lot less polygons than
				// dist-from-midpoint
				VectorSubtract( midxyz, ctrl[i][j].xyz, midxyz );
				VectorSubtract( ctrl[i][j + 2].xyz, ctrl[i][j].xyz, dir );
				VectorNormalize( dir );

				d = DotProduct( midxyz, dir );
				VectorScale( dir, d, projected );
				VectorSubtract( midxyz, projected, midxyz );
				len = VectorLengthSquared( midxyz );            // we will do the sqrt later

				if ( len > maxLen ) {
					maxLen = len;
				}
			}

			maxLen = sqrt( maxLen );
			// if all the points are on the lines, remove the entire columns
			if ( maxLen < 0.1f ) {
				errorTable[dir][j + 1] = 999;
				continue;
			}

			// see if we want to insert subdivided columns
			if ( width + 2 > MAX_GRID_SIZE ) {
				errorTable[dir][j + 1] = 1.0f / maxLen;
				continue;   // can't subdivide any more
			}

			if ( maxLen <= r_subdivisions->value ) {
				errorTable[dir][j + 1] = 1.0f / maxLen;
				continue;   // didn't need subdivision
			}

			errorTable[dir][j + 2] = 1.0f / maxLen;

			// insert two columns and replace the peak
			width += 2;
			for ( i = 0 ; i < height ; i++ ) {
				LerpDrawVert( &ctrl[i][j], &ctrl[i][j + 1], &prev );
				LerpDrawVert( &ctrl[i][j + 1], &ctrl[i][j + 2], &next );
				LerpDrawVert( &prev, &next, &mid );

				for ( k = width - 1 ; k > j + 3 ; k-- ) {
					ctrl[i][k] = ctrl[i][k - 2];
				}
				ctrl[i][j + 1] = prev;
				ctrl[i][j + 2] = mid;
				ctrl[i][j + 3] = next;
			}

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

		}

		Transpose( width, height, ctrl );
		t = width;
		width = height;
		height = t;
	}


	// put all the aproximating points on the curve
	PutPointsOnCurve( ctrl, width, height );

	// cull out any rows or columns that are colinear
	for ( i = 1 ; i < width - 1 ; i++ ) {
		if ( errorTable[0][i] != 999 ) {
			continue;
		}
		for ( j = i + 1 ; j < width ; j++ ) {
			for ( k = 0 ; k < height ; k++ ) {
				ctrl[k][j - 1] = ctrl[k][j];
			}
			errorTable[0][j - 1] = errorTable[0][j];
		}
		width--;
	}

	for ( i = 1 ; i < height - 1 ; i++ ) {
		if ( errorTable[1][i] != 999 ) {
			continue;
		}
		for ( j = i + 1 ; j < height ; j++ ) {
			for ( k = 0 ; k < width ; k++ ) {
				ctrl[j - 1][k] = ctrl[j][k];
			}
			errorTable[1][j - 1] = errorTable[1][j];
		}
		height--;
	}

#if 1
	// flip for longest tristrips as an optimization
	// the results should be visually identical with or
	// without this step
	if ( height > width ) {
		Transpose( width, height, ctrl );
		InvertErrorTable( errorTable, width, height );
		t = width;
		width = height;
		height = t;
		InvertCtrl( width, height, ctrl );
	}
#endif

	// calculate normals
	MakeMeshNormals( width, height, ctrl );

	return R_CreateSurfaceGridMesh( width, height, ctrl, errorTable );
}

/*
===============
R_GridInsertColumn
===============
*/
srfGridMesh_t *R_GridInsertColumn( srfGridMesh_t *grid, int column, int row, vec3_t point, float loderror ) {
	int i, j;
	int width, height, oldwidth;
	MAC_STATIC drawVert_t ctrl[MAX_GRID_SIZE][MAX_GRID_SIZE];
	float errorTable[2][MAX_GRID_SIZE];
	float lodRadius;
	vec3_t lodOrigin;

	oldwidth = 0;
	width = grid->width + 1;
	if ( width > MAX_GRID_SIZE ) {
		return NULL;
	}
	height = grid->height;
	for ( i = 0; i < width; i++ ) {
		if ( i == column ) {
			//insert new column
			for ( j = 0; j < grid->height; j++ ) {
				LerpDrawVert( &grid->verts[j * grid->width + i - 1], &grid->verts[j * grid->width + i], &ctrl[j][i] );
				if ( j == row ) {
					VectorCopy( point, ctrl[j][i].xyz );
				}
			}
			errorTable[0][i] = loderror;
			continue;
		}
		errorTable[0][i] = grid->widthLodError[oldwidth];
		for ( j = 0; j < grid->height; j++ ) {
			ctrl[j][i] = grid->verts[j * grid->width + oldwidth];
		}
		oldwidth++;
	}
	for ( j = 0; j < grid->height; j++ ) {
		errorTable[1][j] = grid->heightLodError[j];
	}
	// put all the aproximating points on the curve
	//PutPointsOnCurve( ctrl, width, height );
	// calculate normals
	MakeMeshNormals( width, height, ctrl );

	VectorCopy( grid->lodOrigin, lodOrigin );
	lodRadius = grid->lodRadius;
	// free the old grid
	R_FreeSurfaceGridMesh( grid );
	// create a new grid
	grid = R_CreateSurfaceGridMesh( width, height, ctrl, errorTable );
	grid->lodRadius = lodRadius;
	VectorCopy( lodOrigin, grid->lodOrigin );
	return grid;
}

/*
===============
R_GridInsertRow
===============
*/
srfGridMesh_t *R_GridInsertRow( srfGridMesh_t *grid, int row, int column, vec3_t point, float loderror ) {
	int i, j;
	int width, height, oldheight;
	MAC_STATIC drawVert_t ctrl[MAX_GRID_SIZE][MAX_GRID_SIZE];
	float errorTable[2][MAX_GRID_SIZE];
	float lodRadius;
	vec3_t lodOrigin;

	oldheight = 0;
	width = grid->width;
	height = grid->height + 1;
	if ( height > MAX_GRID_SIZE ) {
		return NULL;
	}
	for ( i = 0; i < height; i++ ) {
		if ( i == row ) {
			//insert new row
			for ( j = 0; j < grid->width; j++ ) {
				LerpDrawVert( &grid->verts[( i - 1 ) * grid->width + j], &grid->verts[i * grid->width + j], &ctrl[i][j] );
				if ( j == column ) {
					VectorCopy( point, ctrl[i][j].xyz );
				}
			}
			errorTable[1][i] = loderror;
			continue;
		}
		errorTable[1][i] = grid->heightLodError[oldheight];
		for ( j = 0; j < grid->width; j++ ) {
			ctrl[i][j] = grid->verts[oldheight * grid->width + j];
		}
		oldheight++;
	}
	for ( j = 0; j < grid->width; j++ ) {
		errorTable[0][j] = grid->widthLodError[j];
	}
	// put all the aproximating points on the curve
	//PutPointsOnCurve( ctrl, width, height );
	// calculate normals
	MakeMeshNormals( width, height, ctrl );

	VectorCopy( grid->lodOrigin, lodOrigin );
	lodRadius = grid->lodRadius;
	// free the old grid
	R_FreeSurfaceGridMesh( grid );
	// create a new grid
	grid = R_CreateSurfaceGridMesh( width, height, ctrl, errorTable );
	grid->lodRadius = lodRadius;
	VectorCopy( lodOrigin, grid->lodOrigin );
	return grid;
}
