3D/Source/tmap.c

/*

Copyright (C) 2015-2018 Night Dive Studios, LLC.

This program 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.

This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

*/
// $Source: r:/prj/lib/src/3d/RCS/tmap.asm $
// $Revision: 1.30 $
// $Author: jaemz $
// $Date: 1994/09/06 00:12:15 $
//
// Texture mappers
//
// $Log: tmap.asm $
// Revision 1.30  1994/09/06  00:12:15  jaemz
// Externed vbuf2 and nvert so we can peek at them later
//
// Revision 1.29  1994/08/18  03:47:36  jaemz
// added underscore for c to stereo globvs
//
// Revision 1.28  1994/08/16  18:37:43  kevin
// moved constants to 2d.inc.  Modified code for compatability with new 2d.
//
// Revision 1.27  1994/08/04  16:36:36  jaemz
// *** empty log message ***
//
// Revision 1.26  1994/07/21  22:44:46  jaemz
// arrrgh
//
// Revision 1.25  1994/07/19  13:48:47  jaemz
// Added support for stereo
//
// Revision 1.24  1994/07/06  22:37:14  kevin
// use per_umap directly instead of going through canvas table.
//
// Revision 1.23  1994/05/19  09:41:20  kevin
// g3_light(draw)_t(l,floor_,wall_)map now use watcom register passing
// conventions. All perspective maps pass linearity tests.  Non/power/of/2
// bitmaps are punted (for now). Point copy loop has been somewhat optimized.
//
// Revision 1.22  1994/05/04  18:46:44  kevin
// Do clut lighting check correctly.  Check floors and full perspective
// tmaps for linearity.
//
// Revision 1.21  1994/05/02  23:00:52  kevin
// Added support for wall and floor specific texture maps.
//
// Revision 1.20  1993/12/27  21:29:32  kevin
// Hacked in rsd support.
//
// Revision 1.19  1993/12/04  12:44:22  kevin
// Changed 2d calls to conform to new icanvas.inc.
//
// Revision 1.18  1993/10/25  16:28:48  kaboom
// Same bug as last time for g3_draw_tmap.
//
// Revision 1.17  1993/10/22  12:58:02  kaboom
// Fixed bug in quad_tile routines---was losing pointer to vertices.
//
// Revision 1.16  1993/10/22  09:35:26  kaboom
// Added new linear map routines.
//
// Revision 1.15  1993/10/13  13:38:05  kevin
// Changed copy_loop to scale to full bitmap; hopefully without causing
// wrapping.
//
// Revision 1.14  1993/10/03  10:20:30  kaboom
// Fixed 2 register saving bugs.  Also cleanup up code a little.
//
// Revision 1.13  1993/10/02  11:02:07  kaboom
// Changed names of clip_{line,polygon} to g3_clip_{line,polygon} to avoid
// name collisions.
//
// Revision 1.12  1993/10/02  09:29:54  kaboom
// Now calls uv versions of 2d primitives.
//
// Revision 1.11  1993/08/11  15:02:14  kaboom
// Added support for lighting texture mappers.
//
// Revision 1.10  1993/08/10  22:54:27  dc
// add _3d.inc to includes
//
// Revision 1.9  1993/07/08  23:37:54  kaboom
// Changed old use of align field in grs_bitmap to new wlog and hlog.
//
// Revision 1.8  1993/06/16  14:05:06  kaboom
// Replaced code for tiling in calc_warp_matrix accidentally deleted in
// last revision.
//
// Revision 1.7  1993/06/15  19:00:49  kaboom
// Fixed overflow and scaling problems with warp matrix calculation.
//
// Revision 1.6  1993/06/09  15:34:29  kaboom
// Fixed non-initialization of codes for g3_draw_tmap_tile, which
// sometimes caused massive destruction.
//
// Revision 1.5  1993/06/09  04:24:25  kaboom
// Changed g3_draw_tmap_tile to take basis vectors instead of texture map
// width and height.
//
// Revision 1.4  1993/05/11  15:24:21  matt
// Changed g3_draw_tmap_tile() to reuse warp matrix if anchor==0
//
// Revision 1.3  1993/05/11  15:02:00  matt
// Fixed an overflow problem in the warp matrix setup
//
// Revision 1.2  1993/05/10  15:07:51  matt
// Fixed g3_draw_tmap_quad_tile(), which didn't do divide for width and height
// count, so always acted like w,h=1,1.
//
// Revision 1.1  1993/05/04  17:39:54  matt
// Initial revision
//

#include "3d.h"
#include "GlobalV.h"
#include "lg.h"

extern void per_umap(grs_bitmap *bm, int n, grs_vertex **vpl, grs_tmap_info *ti);
extern void h_umap(grs_bitmap *bm, int n, grs_vertex **vpl, grs_tmap_info *ti);
extern void v_umap(grs_bitmap *bm, int n, grs_vertex **vpl, grs_tmap_info *ti);

// prototypes
int do_tmap_tile(g3s_phandle upperleft, g3s_vector *u_vec, g3s_vector *v_vec, int nverts, g3s_phandle *vp,
                 grs_bitmap *bm);
int do_check_tmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count);
int do_tmap(int n, g3s_phandle *vp, grs_bitmap *bm);
int do_tmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count);
void calc_warp_matrix2(g3s_phandle upperleft, fix x10, fix x20, fix y10, fix y20, fix z10, fix z20, grs_bitmap *bm);
int draw_tmap_common(int n, g3s_phandle *vp, grs_bitmap *bm);
int check_linear(int w);

#define _bm_w 8
#define _bm_h 10

void *tmap_func;
grs_bitmap unpack_bm;
grs_tmap_info ti;
grs_tmap_info *ti_ptr = &ti;

// matrix for 2d
fix warp[9];

long light_flag;

// arrays of point handles, used in clipping
extern g3s_phandle vbuf[];
extern g3s_phandle _vbuf2[];

// array of 2d points
extern grs_vertex p_vlist[];
extern grs_vertex *p_vpl[];
extern long _n_verts;

// tiles a texture map over an arbitarary polygon.
// takes eax=upperleft, ebx=width, ecx=height, edx=nverts, esi=ptr to points,
// edi=ptr to bitmap
int g3_draw_lmap_tile(g3s_phandle upperleft, g3s_vector *u_vec, g3s_vector *v_vec, int nverts, g3s_phandle *vp,
                      grs_bitmap *bm) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_BILIN;
    ti.flags = 0;
    light_flag = 0;
    return (do_tmap_tile(upperleft, u_vec, v_vec, nverts, vp, bm));
}

int g3_light_lmap_tile(g3s_phandle upperleft, g3s_vector *u_vec, g3s_vector *v_vec, int nverts, g3s_phandle *vp,
                       grs_bitmap *bm) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_LIT_BILIN;
    ti.flags = 0;
    light_flag = 1;
    return (do_tmap_tile(upperleft, u_vec, v_vec, nverts, vp, bm));
}

int g3_light_tmap_tile(g3s_phandle upperleft, g3s_vector *u_vec, g3s_vector *v_vec, int nverts, g3s_phandle *vp,
                       grs_bitmap *bm) {
    tmap_func = (void *)&per_umap;
    ti.tmap_type = GRC_LIT_PER;
    ti.flags = 0;
    light_flag = 1;
    return (do_tmap_tile(upperleft, u_vec, v_vec, nverts, vp, bm));
}

int g3_draw_tmap_tile(g3s_phandle upperleft, g3s_vector *u_vec, g3s_vector *v_vec, int nverts, g3s_phandle *vp,
                      grs_bitmap *bm) {
    tmap_func = (void *)&per_umap;
    ti.tmap_type = GRC_PER;
    ti.flags = 0;
    light_flag = 0;
    return (do_tmap_tile(upperleft, u_vec, v_vec, nverts, vp, bm));
}

int do_tmap_tile(g3s_phandle upperleft, g3s_vector *u_vec, g3s_vector *v_vec, int nverts, g3s_phandle *vp,
                 grs_bitmap *bm) {
    byte andcode, orcode;
    int i;
    g3s_phandle *src;
    g3s_phandle tempHand;
    fix x10;
    fix y10;
    fix z10;
    fix x20;
    fix y20;
    fix z20;

    // get codes for this polygon
    andcode = 0xff;
    orcode = 0;
    src = vp;
    for (i = nverts; i > 0; i--) {
        tempHand = *(src++);
        andcode &= tempHand->codes;
        orcode |= tempHand->codes;
    }

    // check codes for trivial reject.
    if (andcode)
        return CLIP_ALL;

    // upper left handle of 0 means reuse old warp matrix.

    // store elements of u difference vector as 10 warp differences.
    x10 = u_vec->gX;
    y10 = u_vec->gY;
    z10 = u_vec->gZ;

    // store elements of v difference vector as 20 warp differences.
    x20 = v_vec->gX;
    y20 = v_vec->gY;
    z20 = v_vec->gZ;

    // do warp matrix calculations
    calc_warp_matrix2(upperleft, x10, x20, y10, y20, z10, z20, bm);

    src = vp;
    for (i = nverts; i > 0; i--) {
        fix a, b;
        fix blah1;
        fix blah2;
        fix blah3;

        tempHand = *(src++);
        a = fix_div(tempHand->gX, tempHand->gZ);
        b = fix_div(tempHand->gY, tempHand->gZ);

        blah1 = fix_mul(warp[0], a) + fix_mul(warp[1], b) + warp[2];
        blah2 = fix_mul(warp[3], a) + fix_mul(warp[4], b) + warp[5];
        blah3 = fix_mul(warp[6], a) + fix_mul(warp[7], b) + warp[8];

        tempHand->uv.u = fix_div(blah1, blah3) >> 8;
        tempHand->uv.v = fix_div(blah2, blah3) >> 8;
        tempHand->p3_flags |= PF_U | PF_V;
    }

    return (draw_tmap_common(nverts, vp, bm));
}

int g3_check_and_draw_lmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_BILIN;
    ti.flags = 0;
    light_flag = 0;
    return (do_check_tmap_quad_tile(vp, bm, width_count, height_count));
}

int g3_check_and_light_lmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_LIT_BILIN;
    ti.flags = 0;
    light_flag = 1;
    return (do_check_tmap_quad_tile(vp, bm, width_count, height_count));
}

int g3_check_and_light_tmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    tmap_func = (void *)&per_umap;
    ti.tmap_type = GRC_LIT_PER;
    ti.flags = 0;
    light_flag = 1;
    return (do_check_tmap_quad_tile(vp, bm, width_count, height_count));
}

int g3_check_and_draw_tmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    tmap_func = (void *)&per_umap;
    ti.tmap_type = GRC_PER;
    ti.flags = 0;
    light_flag = 0;
    return (do_check_tmap_quad_tile(vp, bm, width_count, height_count));
}

int do_check_tmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    if (g3_check_poly_facing(vp[0], vp[1], vp[2]))
        return do_tmap_quad_tile(vp, bm, width_count, height_count);
    else
        return CLIP_ALL;
}

// takes eax=nverts edx=ptr to points, ebx=ptr to bitmap
int g3_draw_floor_map(int n, g3s_phandle *vp, grs_bitmap *bm) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_FLOOR;
    ti.flags = TMF_FLOOR;
    light_flag = 0;
    return (do_tmap(n, vp, bm));
}

int g3_light_floor_map(int n, g3s_phandle *vp, grs_bitmap *bm) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_LIT_FLOOR;
    ti.flags = TMF_FLOOR;
    light_flag = 1;
    return (do_tmap(n, vp, bm));
}

int g3_draw_wall_map(int n, g3s_phandle *vp, grs_bitmap *bm) {
    tmap_func = (void *)&v_umap;
    ti.tmap_type = GRC_WALL1D;
    ti.flags = TMF_WALL;
    light_flag = 0;
    return (do_tmap(n, vp, bm));
}

int g3_light_wall_map(int n, g3s_phandle *vp, grs_bitmap *bm) {
    tmap_func = (void *)&v_umap;
    ti.tmap_type = GRC_LIT_WALL1D;
    ti.flags = TMF_WALL;
    light_flag = 1;
    return (do_tmap(n, vp, bm));
}

int g3_draw_lmap(int n, g3s_phandle *vp, grs_bitmap *bm) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_BILIN;
    ti.flags = 0;
    light_flag = 0;
    return (do_tmap(n, vp, bm));
}

int g3_light_lmap(int n, g3s_phandle *vp, grs_bitmap *bm) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_LIT_BILIN;
    ti.flags = 0;
    light_flag = 1;
    return (do_tmap(n, vp, bm));
}

int g3_light_tmap(int n, g3s_phandle *vp, grs_bitmap *bm) {
    tmap_func = (void *)&per_umap;
    ti.tmap_type = GRC_LIT_PER;
    ti.flags = 0;
    light_flag = 1;
    return (do_tmap(n, vp, bm));
}

int g3_draw_tmap(int n, g3s_phandle *vp, grs_bitmap *bm) {
    tmap_func = (void *)&per_umap;
    ti.tmap_type = GRC_PER;
    ti.flags = 0;
    light_flag = 0;
    return (do_tmap(n, vp, bm));
}

int do_tmap(int n, g3s_phandle *vp, grs_bitmap *bm) {
    byte andcode, orcode;
    int i;
    g3s_phandle *src;
    g3s_phandle tempHand;

// clang-format off
#ifdef stereo_on
  test    _g3d_stereo,1
  jz      no_stereo1
  push    eax                // calling destroys eax
  mov     ecx,d [ti_ptr]
  push    ecx
  mov     ecx,d [ti_ptr+4]
  push    ecx
  mov     ecx,tmap_func
  push    ecx
  mov     ecx,light_flag
  push    ecx
  call    do_tmap_raw
  pop     eax
  mov     light_flag,eax
  pop     eax
  mov     tmap_func,eax
  pop     eax
  mov     d [ti_ptr+4],eax
  pop     eax
  mov     d [ti_ptr],eax
  pop     eax

  pushm eax,ebx           // copy list and codes and uv and rgb and i
  // num  points,pointer to  bmap

  move_to_stereo_and_uvi

  set_rt_canv

  popm eax,ebx
  call do_tmap_raw

  set_lt_canv
  popad
  ret

do_tmap_raw:
  pushad
no_stereo1:
#endif

        // clang-format on

        // convert RSD bitmap to normal
        if (bm->type == BMT_RSD8) {
        if (gr_rsd8_convert(bm, &unpack_bm) != GR_UNPACK_RSD8_OK)
            return CLIP_ALL;
        else
            bm = &unpack_bm;
    }

    // get codes for this polygon
    andcode = 0xff;
    orcode = 0;
    src = vp;
    for (i = n; i > 0; i--) {
        tempHand = *(src++);
        andcode &= tempHand->codes;
        orcode |= tempHand->codes;
    }

    // check codes for trivial reject.
    if (andcode)
        return CLIP_ALL;

    return (draw_tmap_common(n, vp, bm));
}

// draws a square texture map, where the corners of the 3d quad match the
// corners of the bitmap
// takes esi=ptr to points, edi=ptr to bitmap, eax=width count, ebx=height count
int g3_draw_lmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_BILIN;
    ti.flags = 0;
    light_flag = 0;
    return (do_tmap_quad_tile(vp, bm, width_count, height_count));
}

int g3_light_lmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    tmap_func = (void *)&h_umap;
    ti.tmap_type = GRC_LIT_BILIN;
    ti.flags = 0;
    light_flag = 1;
    return (do_tmap_quad_tile(vp, bm, width_count, height_count));
}

int g3_light_tmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    tmap_func = (void *)&per_umap;
    ti.tmap_type = GRC_LIT_PER;
    ti.flags = 0;
    light_flag = 1;
    return (do_tmap_quad_tile(vp, bm, width_count, height_count));
}

int g3_draw_tmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    tmap_func = (void *)&per_umap;
    ti.tmap_type = GRC_PER;
    ti.flags = 0;
    light_flag = 0;
    return (do_tmap_quad_tile(vp, bm, width_count, height_count));
}

int do_tmap_quad_tile(g3s_phandle *vp, grs_bitmap *bm, int width_count, int height_count) {
    int temp_w, temp_h;
    byte andcode, orcode;
    int i;
    g3s_phandle *src;
    g3s_phandle tempHand;

    temp_w = width_count << 8;
    temp_h = height_count << 8;
    _n_verts = 4;

    vp[0]->uv.u = vp[0]->uv.v = 0;
    vp[0]->p3_flags |= PF_U | PF_V;

    vp[1]->uv.u = temp_w;
    vp[1]->uv.v = 0;
    vp[1]->p3_flags |= PF_U | PF_V;

    vp[2]->uv.u = temp_w;
    vp[2]->uv.v = temp_h;
    vp[2]->p3_flags |= PF_U | PF_V;

    vp[3]->uv.u = 0;
    vp[3]->uv.v = temp_h;
    vp[3]->p3_flags |= PF_U | PF_V;

    // first, go though points and get codes
    andcode = 0xff;
    orcode = 0;
    src = vp;
    for (i = 4; i > 0; i--) {
        tempHand = *(src++);
        andcode &= tempHand->codes;
        orcode |= tempHand->codes;
    }

    // check codes for trivial reject.
    if (andcode)
        return CLIP_ALL;

    return (draw_tmap_common(4, vp, bm));
}

int draw_tmap_common(int n, g3s_phandle *vp, grs_bitmap *bm) {
    int branch_to_copy = 0;
    int hlog, wlog;
    g3s_phandle temphand;
    int i, temp;
    grs_vertex *cur_vert;

    // always clip for now
    // copy to temp buffer for clipping
    // BlockMove(vp,vbuf,n*4);
    memmove(vbuf, vp, n * sizeof *vbuf);

    _n_verts = n = g3_clip_polygon(n, vbuf, _vbuf2);
    if (n == 0)
        return CLIP_ALL;
    if (ti.tmap_type >= GRC_CLUT_BILIN + 2)
        branch_to_copy = check_linear(n);
    else
        branch_to_copy = 1;

    // check if bitmap is power of 2
    wlog = bm->wlog;
    hlog = bm->hlog;

    if (((1 << wlog) != bm->w) || ((1 << hlog) != bm->h))
        return CLIP_ALL;

    wlog += 8;
    hlog += 8;

    // now, copy 2d points to buffer for tmap call, projecting if neccesary
    //	for (i=n-1; i--; i>=0)
    for (i = 0; i < n; i++) {
        temphand = _vbuf2[i];
        p_vpl[i] = cur_vert = &p_vlist[i];

        // check if this point has been projected
        if ((temphand->p3_flags & PF_PROJECTED) == 0)
            g3_project_point(temphand);

        cur_vert->x = temphand->sx;
        cur_vert->y = temphand->sy;

        temp = temphand->uv.u;
        if (temp <= 0)
            temp++;
        else
            temp--;
        cur_vert->u = temp << wlog;

        temp = temphand->uv.v;
        if (temp <= 0)
            temp++;
        else
            temp--;
        cur_vert->v = temp << hlog;

        cur_vert->i = temphand->i << 8;

        if (!branch_to_copy) // fix Z
        {
            temp = temphand->gZ;
            cur_vert->w = fix_div(0x010000, temp); // 1/Z
        }
    }

    if (!light_flag) {
        ((void (*)(grs_bitmap * bm, int n, grs_vertex **vpl, grs_tmap_info *ti)) tmap_func)(bm, _n_verts, p_vpl, &ti);
        return CLIP_NONE;
    } else {
        extern fix gr_clut_lit_tol;
        int temp_n;
        fix imax, imin, temp_i;
        grs_vertex *temp_p_vlist;

        temp_p_vlist = p_vlist;
        temp_n = n - 1;
        imax = imin = temp_p_vlist[temp_n].i;
        while (--n >= 0) {
            temp_i = temp_p_vlist[n].i;
            if (temp_i < imin)
                imin = temp_i;
            if (temp_i > imax)
                imax = temp_i;
        }

        temp_i = imax - imin;
        if (temp_i >= gr_clut_lit_tol) {
            ((void (*)(grs_bitmap * bm, int n, grs_vertex **vpl, grs_tmap_info *ti)) tmap_func)(bm, _n_verts, p_vpl,
                                                                                                &ti);
            return CLIP_NONE;
        } else {
            uchar *temp_ptr;

            imin += imax;
            imin >>= 9;
            imin &= 0xff00;
            temp_ptr = gr_get_light_tab() + imin;
            ti.clut = temp_ptr;
            ti.tmap_type += 2;
            ti.flags |= TMF_CLUT;

            ((void (*)(grs_bitmap * bm, int n, grs_vertex **vpl, grs_tmap_info *ti)) tmap_func)(bm, _n_verts, p_vpl,
                                                                                                &ti);
            return CLIP_NONE;
        }
    }
}

// return 1 if punt (ignore Z), 0 if use it
int check_linear(int n) {
    extern ubyte flat8_per_ltol;
    g3s_phandle temphand;
    fix zmin, zmax;
    fix temp;
    g3s_phandle *temp_vbuf2;

    temp_vbuf2 = _vbuf2;
    n--;
    temphand = temp_vbuf2[n];
    zmax = zmin = temphand->gZ;

    while (--n >= 0) {
        temphand = temp_vbuf2[n];
        temp = temphand->gZ;

        if (temp < zmin)
            zmin = temp;
        if (temp > zmax)
            zmax = temp;
    }

    zmax -= zmin;
    temp = zmin >> flat8_per_ltol;
    if (temp >= zmax) {
        ti.tmap_type = GRC_BILIN + (light_flag << 1);
        tmap_func = (void *)&h_umap;
        return 1; // punt
    } else
        return 0; // use Z
}

// compute warp matrix with deltas already set.
// arguments:
//   deltas in x10,x20,y10,y20,z10,z20
//   pointer to bitmap in bm_ptr
//   esi=basis 0
void calc_warp_matrix2(g3s_phandle upperleft, fix x10, fix x20, fix y10, fix y20, fix z10, fix z20, grs_bitmap *bm) {
    fix x0 = upperleft->gX;
    fix y0 = upperleft->gY;
    fix z0 = upperleft->gZ;

    // compute the actual matrix.

    warp[0] = fix_mul(y20, z0) - fix_mul(y0, z20);
    warp[1] = fix_mul(x0, z20) - fix_mul(x20, z0);
    warp[2] = fix_mul(x20, y0) - fix_mul(x0, y20);
    warp[3] = fix_mul(y0, z10) - fix_mul(y10, z0);
    warp[4] = fix_mul(x10, z0) - fix_mul(x0, z10);
    warp[5] = fix_mul(x0, y10) - fix_mul(x10, y0);
    warp[6] = fix_mul(y10, z20) - fix_mul(y20, z10);
    warp[7] = fix_mul(x20, z10) - fix_mul(x10, z20);
    warp[8] = fix_mul(x10, y20) - fix_mul(x20, y10);
}

// ------------------------------------------------------------------------------------------------
// MLA - calc_warp_matrix never called! none of this stuff used!?

/*
getdel  macro   dest,ofs,src1,src2
       mov     eax,[src1].ofs
       sub     eax,[src2].ofs
       break_if        o,'overflow in getdel'
       mov     dest,eax
       endm

divm    macro   dest,reg
       mov     eax,dest
       cdq
       idiv    reg
       mov     dest,eax
       endm


// figure out the goofy warp matrix.
// takes three points: ebx,ecx,edx=basis 0,1,2 and bm_ptr must point to
// the address of the bitmap.
// only handles square bitmaps now.
void calc_warp_matrix(void)
{
// get deltas
// x10 = r1->x - r0->x   x20 = r2->x - r0->x
// y10 = r1->y - r0->y   y20 = r2->y - r0->y
// z10 = r1->z - r0->z   z20 = r2->z - r0->z
       // get 10 differences.
       getdel  x10,x,ecx,ebx
       getdel  y10,y,ecx,ebx
       getdel  z10,z,ecx,ebx
       // get 20 differences.
       getdel  x20,x,edx,ebx
       getdel  y20,y,edx,ebx
       getdel  z20,z,edx,ebx
       mov     esi,ebx                 // esi -> basis0

       mov     ebx,width_count
       cmp     ebx,1
       je      skip_w_div
       divm    x10,ebx
       divm    y10,ebx
       divm    z10,ebx
skip_w_div:
       mov     ebx,height_count
       cmp     ebx,1
       je      skip_h_div
       divm    x20,ebx
       divm    y20,ebx
       divm    z20,ebx
skip_h_div:
                               jmp			calc_warp_matrix2
}
 */