1 /*
2
3 Copyright (C) 2015-2018 Night Dive Studios, LLC.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
17
18 */
19 /*
20 * $Source: r:/prj/lib/src/2d/RCS/fl8cply.c $
21 * $Revision: 1.2 $
22 * $Author: kevin $
23 * $Date: 1994/10/17 14:59:58 $
24 *
25 * Routines for drawing flat shaded polygons onto a flat 8 canvas.
26 *
27 * This file is part of the 2d library.
28 */
29
30 #include "cnvdat.h"
31 #include "fix.h"
32 #include "gente.h"
33 #include "poly.h"
34 #include "rgb.h"
35 #include "scrdat.h"
36 #include "tmapint.h"
37
38 // prototypes
39 int gri_cpoly_loop(grs_tmap_loop_info *ti);
40 void gri_cpoly_init(grs_tmap_loop_info *ti);
41 void gri_clut_cpoly_init(grs_tmap_loop_info *ti);
42
gri_cpoly_loop(grs_tmap_loop_info * ti)43 int gri_cpoly_loop(grs_tmap_loop_info *ti) {
44 int x, d;
45 fix dx, frac;
46 fix r, g, b, dr, dg, db;
47
48 do {
49 dx = ti->right.x - ti->left.x;
50 frac = fix_ceil(ti->left.x) - ti->left.x;
51
52 r = ti->left.u;
53 dr = fix_div(ti->right.u - r, dx);
54 r += fix_mul(frac, dr);
55
56 g = ti->left.v;
57 dg = fix_div(ti->right.v - g, dx);
58 g += fix_mul(frac, dg);
59
60 b = ti->left.i;
61 db = fix_div(ti->right.i - b, dx);
62 b += fix_mul(frac, db);
63
64 if ((d = fix_cint(ti->right.x) - fix_cint(ti->left.x)) > 0) {
65 switch (ti->bm.hlog) {
66 case GRL_OPAQUE:
67 for (x = fix_cint(ti->left.x); x < fix_cint(ti->right.x); x++) {
68 int j = gr_index_rgb(r, g, b);
69 ti->d[x] = grd_ipal[j];
70 r += dr, g += dg, b += db;
71 }
72 break;
73 case GRL_CLUT:
74 for (x = fix_cint(ti->left.x); x < fix_cint(ti->right.x); x++) {
75 int j = gr_index_rgb(r, g, b);
76 ti->d[x] = ti->clut[grd_ipal[j]];
77 r += dr, g += dg, b += db;
78 }
79 break;
80 }
81 } else if (d < 0) {
82 return TRUE;
83 }
84 /* update span extrema and destination. */
85 ti->left.x += ti->left.dx;
86 ti->right.x += ti->right.dx;
87 ti->left.u += ti->left.du;
88 ti->right.u += ti->right.du;
89 ti->left.v += ti->left.dv;
90 ti->right.v += ti->right.dv;
91 ti->left.i += ti->left.di;
92 ti->right.i += ti->right.di;
93 ti->d += grd_bm.row;
94 } while ((--(ti->n)) > 0);
95 return FALSE;
96 }
97
gri_cpoly_init(grs_tmap_loop_info * ti)98 void gri_cpoly_init(grs_tmap_loop_info *ti) {
99 ti->bm.hlog = GRL_OPAQUE;
100 ti->d = ti->y * grd_bm.row + grd_bm.bits;
101 ti->loop_func = (void (*)())gri_cpoly_loop;
102 ti->top_edge_func = (void (*)())gri_rgbx_edge;
103 ti->bot_edge_func = (void (*)())gri_rgbx_edge;
104 }
105
gri_clut_cpoly_init(grs_tmap_loop_info * ti)106 void gri_clut_cpoly_init(grs_tmap_loop_info *ti) {
107 ti->bm.hlog = GRL_CLUT;
108 ti->d = ti->y * grd_bm.row + grd_bm.bits;
109 ti->loop_func = (void (*)())gri_cpoly_loop;
110 ti->top_edge_func = (void (*)())gri_rgbx_edge;
111 ti->bot_edge_func = (void (*)())gri_rgbx_edge;
112 }
113