tr_curve.c

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/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena 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 2 of the License,
or (at your option) any later version.

Quake III Arena 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 Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  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];

    Com_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 = /*ri.Hunk_Alloc*/ ri.Malloc( size );
    Com_Memset(grid, 0, size);

    grid->widthLodError = /*ri.Hunk_Alloc*/ ri.Malloc( width * 4 );
    Com_Memcpy( grid->widthLodError, errorTable[0], width * 4 );

    grid->heightLodError = /*ri.Hunk_Alloc*/ ri.Malloc( height * 4 );
    Com_Memcpy( grid->heightLodError, errorTable[1], height * 4 );
#else
    grid = ri.Hunk_Alloc( size );
    Com_Memset(grid, 0, size);

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

    grid->heightLodError = ri.Hunk_Alloc( height * 4 );
    Com_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 ) {
    ri.Free(grid->widthLodError);
    ri.Free(grid->heightLodError);
    ri.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      midxyz2;
                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, midxyz2);
                len = VectorLengthSquared( midxyz2 );           // 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;
}

---