2 blender for the Gameboy Advance
3 Copyright (C) 2021 John Tsiombikas <nuclear@member.fsf.org>
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.
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.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>.
24 #define MAT_STACK_SIZE 4
27 static int32_t mat[MAT_STACK_SIZE][16];
29 static unsigned int opt;
30 static int32_t ldir[3];
32 static void draw_ptlines(int prim, const struct xvertex *varr, int vcount);
37 xgl_viewport(0, 0, 240, 160);
40 ldir[0] = ldir[1] = 0;
44 void xgl_enable(unsigned int o)
49 void xgl_disable(unsigned int o)
54 void xgl_viewport(int x, int y, int w, int h)
62 void xgl_push_matrix(void)
66 if(mtop >= MAT_STACK_SIZE - 1) return;
69 memcpy(mat[mtop], mat[prev], sizeof mat[0]);
72 void xgl_pop_matrix(void)
77 static const int32_t id[] = {
84 void xgl_load_identity(void)
89 void xgl_load_matrix(const int32_t *m)
91 memcpy(mat[mtop], m, sizeof mat[0]);
94 #define M(i,j) (((i) << 2) + (j))
95 #define XMUL(a, b) (((a) >> 8) * ((b) >> 8))
96 void xgl_mult_matrix(const int32_t *m2)
100 int32_t *dest = mat[mtop];
102 memcpy(m1, dest, sizeof m1);
106 *dest++ = XMUL(m1[M(0, j)], m2[M(i, 0)]) +
107 XMUL(m1[M(1, j)], m2[M(i, 1)]) +
108 XMUL(m1[M(2, j)], m2[M(i, 2)]) +
109 XMUL(m1[M(3, j)], m2[M(i, 3)]);
114 #define XSIN(x) (int32_t)(sin(x / 65536.0f) * 65536.0f)
115 #define XCOS(x) (int32_t)(cos(x / 65536.0f) * 65536.0f)
117 void xgl_translate(int32_t x, int32_t y, int32_t z)
119 int32_t m[16] = {0x10000, 0, 0, 0, 0, 0x10000, 0, 0, 0, 0, 0x10000, 0, 0, 0, 0, 0x10000};
126 void xgl_rotate_x(int32_t angle)
128 int32_t m[16] = {0x10000, 0, 0, 0, 0, 0x10000, 0, 0, 0, 0, 0x10000, 0, 0, 0, 0, 0x10000};
129 int32_t sa = XSIN(angle);
130 int32_t ca = XCOS(angle);
138 void xgl_rotate_y(int32_t angle)
140 int32_t m[16] = {0x10000, 0, 0, 0, 0, 0x10000, 0, 0, 0, 0, 0x10000, 0, 0, 0, 0, 0x10000};
141 int32_t sa = XSIN(angle);
142 int32_t ca = XCOS(angle);
150 void xgl_rotate_z(int32_t angle)
152 int32_t m[16] = {0x10000, 0, 0, 0, 0, 0x10000, 0, 0, 0, 0, 0x10000, 0, 0, 0, 0, 0x10000};
153 int32_t sa = XSIN(angle);
154 int32_t ca = XCOS(angle);
162 void xgl_scale(int32_t x, int32_t y, int32_t z)
172 static void xform(struct xvertex *out, const struct xvertex *in, const int32_t *m)
174 out->x = XMUL(m[0], in->x) + XMUL(m[4], in->y) + XMUL(m[8], in->z) + m[12];
175 out->y = XMUL(m[1], in->x) + XMUL(m[5], in->y) + XMUL(m[9], in->z) + m[13];
176 out->z = XMUL(m[2], in->x) + XMUL(m[6], in->y) + XMUL(m[10], in->z) + m[14];
179 static void xform_norm(struct xvertex *out, const struct xvertex *in, const int32_t *m)
181 out->nx = XMUL(m[0], in->nx) + XMUL(m[4], in->ny) + XMUL(m[8], in->nz);
182 out->ny = XMUL(m[1], in->nx) + XMUL(m[5], in->ny) + XMUL(m[9], in->nz);
183 out->nz = XMUL(m[2], in->nx) + XMUL(m[6], in->ny) + XMUL(m[10], in->nz);
186 /* d = 1.0 / tan(fov/2) */
187 #define PROJ_D 0x20000
189 void xgl_draw(int prim, const struct xvertex *varr, int vcount)
192 struct xvertex xv[4];
193 struct pvertex pv[4];
197 draw_ptlines(prim, varr, vcount);
201 while(vcount >= prim) {
204 xform(xv, varr, mat[mtop]);
205 xform_norm(xv, varr, mat[mtop]);
214 if(opt & XGL_LIGHTING) {
215 ndotl = (xv->nx >> 8) * ldir[0] + (xv->ny >> 8) * ldir[1] + (xv->nz >> 8) * ldir[2];
216 if(ndotl < 0) ndotl = 0;
217 cidx = 128 + (ndotl >> 9);
218 if(cidx > 255) cidx = 255;
221 xv->x = (xv->x << 1) / (xv->z >> 8); /* assume aspect: ~2 */
222 xv->y = (xv->y << 2) / (xv->z >> 8); /* the shift is * PROJ_D */
223 /* projection result is 24.8 */
225 pv->x = (((xv->x + 0x100) >> 1) * vp[2]) + (vp[0] << 8);
226 pv->y = (((0x100 - xv->y) >> 1) * vp[3]) + (vp[1] << 8);
229 for(i=1; i<prim; i++) {
230 xform(xv + i, varr, mat[mtop]);
232 xv[i].x = (xv[i].x << 1) / (xv[i].z >> 8); /* assume aspect: ~2 */
233 xv[i].y = (xv[i].y << 2) / (xv[i].z >> 8); /* the shift is * PROJ_D */
234 /* projection result is 24.8 */
236 pv[i].x = (((xv[i].x + 0x100) >> 1) * vp[2]) + (vp[0] << 8);
237 pv[i].y = (((0x100 - xv[i].y) >> 1) * vp[3]) + (vp[1] << 8);
242 polyfill_flat(pv, prim, cidx);
246 static void draw_ptlines(int prim, const struct xvertex *varr, int vcount)
249 struct xvertex xv[2];
251 while(vcount >= prim) {
252 for(i=0; i<prim; i++) {
253 xform(xv + i, varr, mat[mtop]);
255 xv[i].x = (xv[i].x << 1) / (xv[i].z >> 8); /* assume aspect: ~2 */
256 xv[i].y = (xv[i].y << 2) / (xv[i].z >> 8); /* the shift is * PROJ_D */
257 /* projection result is 24.8 */
259 xv[i].x = ((((xv[i].x + 0x100) >> 1) * vp[2]) >> 8) + vp[0];
260 xv[i].y = ((((0x100 - xv[i].y) >> 1) * vp[3]) >> 8) + vp[1];
266 clip_line((int*)&xv[0].x, (int*)&xv[0].y, (int*)&xv[1].x, (int*)&xv[1].y, vp[0], vp[1], vp[2] - 1, vp[3] - 1);
267 draw_line(xv[0].x, xv[0].y, xv[1].x, xv[1].y, varr[-2].cidx);