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annotate src/mingl.c @ 3:0e781cc43178

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adding textures
author John Tsiombikas <nuclear@member.fsf.org>
date Mon, 21 Nov 2011 10:16:09 +0200
parents f04884489bad
children bce78aaafc68
rev   line source
nuclear@0 1 /*
nuclear@0 2 256-color 3D graphics hack for real-mode DOS.
nuclear@0 3 Copyright (C) 2011 John Tsiombikas <nuclear@member.fsf.org>
nuclear@0 4
nuclear@0 5 This program is free software: you can redistribute it and/or modify
nuclear@0 6 it under the terms of the GNU General Public License as published by
nuclear@0 7 the Free Software Foundation, either version 3 of the License, or
nuclear@0 8 (at your option) any later version.
nuclear@0 9
nuclear@0 10 This program is distributed in the hope that it will be useful,
nuclear@0 11 but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@0 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
nuclear@0 13 GNU General Public License for more details.
nuclear@0 14
nuclear@0 15 You should have received a copy of the GNU General Public License
nuclear@0 16 along with this program. If not, see <http://www.gnu.org/licenses/>.
nuclear@0 17 */
nuclear@0 18 #include <stdio.h>
nuclear@0 19 #include <stdlib.h>
nuclear@0 20 #include <string.h>
nuclear@0 21 #include <math.h>
nuclear@0 22 #include <assert.h>
nuclear@0 23 #include "mingl.h"
nuclear@0 24 #include "mglimpl.h"
nuclear@0 25
nuclear@3 26
nuclear@0 27 #define DOT(a, b) ((a).x * (b).x + (a).y * (b).y + (a).z * (b).z)
nuclear@0 28
nuclear@0 29 static void transform(vec4_t *res, vec4_t *v, float *mat);
nuclear@0 30 static void transform3(vec3_t *res, vec3_t *v, float *mat);
nuclear@0 31 static void vertex_proc(struct vertex *vert);
nuclear@3 32 static int calc_shiftmask(int val, int *shiftp, unsigned int *maskp);
nuclear@0 33
nuclear@0 34 static struct state st;
nuclear@0 35 static struct framebuffer fb;
nuclear@0 36
nuclear@0 37 int mgl_init(int width, int height)
nuclear@0 38 {
nuclear@0 39 int i;
nuclear@0 40
nuclear@0 41 st.flags = 0;
nuclear@0 42 st.mmode = 0;
nuclear@0 43
nuclear@0 44 mgl_front_face(MGL_CCW);
nuclear@0 45 mgl_cull_face(MGL_BACK);
nuclear@0 46
nuclear@0 47 st.curv.cidx = 0;
nuclear@0 48 st.curv.energy = 1.0;
nuclear@0 49 st.curv.norm.x = st.curv.norm.y = st.curv.norm.z = 0.0;
nuclear@0 50
nuclear@0 51 if(!(fb.pixels = malloc(width * height))) {
nuclear@0 52 return -1;
nuclear@0 53 }
nuclear@0 54 fb.width = width;
nuclear@0 55 fb.height = height;
nuclear@0 56 fb.zbuf = 0;
nuclear@0 57
nuclear@0 58 if(mgl_rast_init(&st, &fb) == -1) {
nuclear@0 59 free(fb.pixels);
nuclear@0 60 return -1;
nuclear@0 61 }
nuclear@0 62
nuclear@0 63 st.mtop[0] = st.mtop[1] = 0;
nuclear@0 64
nuclear@0 65 mgl_matrix_mode(MGL_MODELVIEW);
nuclear@0 66 mgl_load_identity();
nuclear@0 67 mgl_matrix_mode(MGL_PROJECTION);
nuclear@0 68 mgl_load_identity();
nuclear@0 69
nuclear@0 70 /* initial viewport in the size of the framebuffer */
nuclear@0 71 st.vp[0] = st.vp[1] = 0;
nuclear@0 72 st.vp[2] = width;
nuclear@0 73 st.vp[3] = height;
nuclear@0 74
nuclear@0 75 st.col_range = 256;
nuclear@0 76 for(i=0; i<MAX_LIGHTS; i++) {
nuclear@0 77 st.ldir[i].x = st.ldir[i].y = 0.0f;
nuclear@0 78 st.ldir[i].z = 1.0f;
nuclear@0 79 st.lint[i] = 0.0f;
nuclear@0 80 }
nuclear@0 81
nuclear@0 82 return 0;
nuclear@0 83 }
nuclear@0 84
nuclear@0 85 void mgl_free(void)
nuclear@0 86 {
nuclear@0 87 mgl_rast_cleanup();
nuclear@0 88 free(fb.pixels);
nuclear@0 89 }
nuclear@0 90
nuclear@0 91 unsigned char *mgl_framebuffer(void)
nuclear@0 92 {
nuclear@0 93 return fb.pixels;
nuclear@0 94 }
nuclear@0 95
nuclear@0 96 void mgl_clear(int cidx)
nuclear@0 97 {
nuclear@0 98 memset(fb.pixels, cidx, fb.width * fb.height);
nuclear@0 99 }
nuclear@0 100
nuclear@0 101 void mgl_enable(unsigned int bit)
nuclear@0 102 {
nuclear@0 103 st.flags |= bit;
nuclear@0 104 }
nuclear@0 105
nuclear@0 106 void mgl_disable(unsigned int bit)
nuclear@0 107 {
nuclear@0 108 st.flags &= ~bit;
nuclear@0 109 }
nuclear@0 110
nuclear@3 111 int mgl_isenabled(unsigned int bit)
nuclear@3 112 {
nuclear@3 113 return (st.flags & bit) != 0;
nuclear@3 114 }
nuclear@3 115
nuclear@0 116 void mgl_front_face(int ff)
nuclear@0 117 {
nuclear@0 118 st.frontface = ff;
nuclear@0 119 }
nuclear@0 120
nuclear@0 121 void mgl_cull_face(int cf)
nuclear@0 122 {
nuclear@0 123 st.cullface = cf;
nuclear@0 124 }
nuclear@0 125
nuclear@0 126 void mgl_color_range(int rng)
nuclear@0 127 {
nuclear@0 128 st.col_range = rng;
nuclear@0 129 }
nuclear@0 130
nuclear@0 131 void mgl_light_intensity(int ltidx, float intens)
nuclear@0 132 {
nuclear@0 133 assert(ltidx >= 0 && ltidx < MAX_LIGHTS);
nuclear@0 134 st.lint[ltidx] = intens;
nuclear@0 135 }
nuclear@0 136
nuclear@0 137 void mgl_light_direction(int ltidx, float x, float y, float z)
nuclear@0 138 {
nuclear@0 139 vec3_t dir;
nuclear@0 140 float mag;
nuclear@0 141 assert(ltidx >= 0 && ltidx < MAX_LIGHTS);
nuclear@0 142
nuclear@0 143 dir.x = x;
nuclear@0 144 dir.y = y;
nuclear@0 145 dir.z = z;
nuclear@0 146 transform3(&st.ldir[ltidx], &dir, st.matrix[MGL_MODELVIEW][st.mtop[MGL_MODELVIEW]]);
nuclear@0 147
nuclear@0 148 mag = sqrt(DOT(st.ldir[ltidx], st.ldir[ltidx]));
nuclear@0 149 if(fabs(mag) < 1e-6) {
nuclear@0 150 mag = 1.0f;
nuclear@0 151 }
nuclear@0 152 st.ldir[ltidx].x /= mag;
nuclear@0 153 st.ldir[ltidx].y /= mag;
nuclear@0 154 st.ldir[ltidx].z /= mag;
nuclear@0 155 }
nuclear@0 156
nuclear@0 157 void mgl_begin(int prim)
nuclear@0 158 {
nuclear@0 159 st.prim = prim;
nuclear@0 160 st.vidx = 0;
nuclear@0 161
nuclear@0 162 st.ord = st.frontface;
nuclear@0 163 if(st.cullface == MGL_FRONT) {
nuclear@0 164 st.ord = st.frontface == MGL_CCW ? MGL_CW : MGL_CCW;
nuclear@0 165 }
nuclear@0 166
nuclear@0 167 /* select the correct rasterizer according to state */
nuclear@0 168 mgl_rast_prepare();
nuclear@0 169 }
nuclear@0 170
nuclear@0 171 void mgl_end(void)
nuclear@0 172 {
nuclear@0 173 }
nuclear@0 174
nuclear@0 175 void mgl_vertex2f(float x, float y)
nuclear@0 176 {
nuclear@0 177 mgl_vertex4f(x, y, 0.0f, 1.0f);
nuclear@0 178 }
nuclear@0 179
nuclear@0 180 void mgl_vertex3f(float x, float y, float z)
nuclear@0 181 {
nuclear@0 182 mgl_vertex4f(x, y, z, 1.0f);
nuclear@0 183 }
nuclear@0 184
nuclear@0 185 void mgl_vertex4f(float x, float y, float z, float w)
nuclear@0 186 {
nuclear@0 187 st.v[st.vidx].pos.x = x;
nuclear@0 188 st.v[st.vidx].pos.y = y;
nuclear@0 189 st.v[st.vidx].pos.z = z;
nuclear@0 190 st.v[st.vidx].pos.w = w;
nuclear@0 191 st.v[st.vidx].cidx = st.curv.cidx;
nuclear@0 192 st.v[st.vidx].energy = st.curv.energy;
nuclear@0 193 st.v[st.vidx].norm = st.curv.norm;
nuclear@0 194 st.v[st.vidx].tc = st.curv.tc;
nuclear@0 195
nuclear@0 196 vertex_proc(st.v + st.vidx);
nuclear@0 197
nuclear@0 198 if(++st.vidx >= st.prim) {
nuclear@0 199 switch(st.prim) {
nuclear@0 200 case MGL_POINTS:
nuclear@0 201 mgl_draw_point(st.v);
nuclear@0 202 break;
nuclear@0 203 case MGL_LINES:
nuclear@0 204 mgl_draw_line(st.v, st.v + 1);
nuclear@0 205 break;
nuclear@0 206 case MGL_TRIANGLES:
nuclear@0 207 case MGL_QUADS:
nuclear@0 208 mgl_draw_poly(st.v, st.prim);
nuclear@0 209 break;
nuclear@0 210 default:
nuclear@0 211 fprintf(stderr, "invalid primitive: %d\n", st.prim);
nuclear@0 212 abort();
nuclear@0 213 }
nuclear@0 214 st.vidx = 0;
nuclear@0 215 }
nuclear@0 216 }
nuclear@0 217
nuclear@0 218 void mgl_color1f(float energy)
nuclear@0 219 {
nuclear@0 220 st.curv.energy = energy;
nuclear@0 221 }
nuclear@0 222
nuclear@0 223 void mgl_index(int c)
nuclear@0 224 {
nuclear@0 225 st.curv.cidx = c;
nuclear@0 226 }
nuclear@0 227
nuclear@0 228 void mgl_normal(float x, float y, float z)
nuclear@0 229 {
nuclear@0 230 st.curv.norm.x = x;
nuclear@0 231 st.curv.norm.y = y;
nuclear@0 232 st.curv.norm.z = z;
nuclear@0 233 }
nuclear@0 234
nuclear@0 235 void mgl_texcoord2f(float x, float y)
nuclear@0 236 {
nuclear@0 237 st.curv.tc.x = x;
nuclear@0 238 st.curv.tc.y = y;
nuclear@0 239 }
nuclear@0 240
nuclear@0 241 static void transform(vec4_t *res, vec4_t *v, float *mat)
nuclear@0 242 {
nuclear@0 243 res->x = mat[0] * v->x + mat[4] * v->y + mat[8] * v->z + mat[12] * v->w;
nuclear@0 244 res->y = mat[1] * v->x + mat[5] * v->y + mat[9] * v->z + mat[13] * v->w;
nuclear@0 245 res->z = mat[2] * v->x + mat[6] * v->y + mat[10] * v->z + mat[14] * v->w;
nuclear@0 246 res->w = mat[3] * v->x + mat[7] * v->y + mat[11] * v->z + mat[15] * v->w;
nuclear@0 247 }
nuclear@0 248
nuclear@0 249 /* the matrix is 4x4 (16 floats), just ignoring anything out of the 3x3 */
nuclear@0 250 static void transform3(vec3_t *res, vec3_t *v, float *mat)
nuclear@0 251 {
nuclear@0 252 res->x = mat[0] * v->x + mat[4] * v->y + mat[8] * v->z;
nuclear@0 253 res->y = mat[1] * v->x + mat[5] * v->y + mat[9] * v->z;
nuclear@0 254 res->z = mat[2] * v->x + mat[6] * v->y + mat[10] * v->z;
nuclear@0 255 }
nuclear@0 256
nuclear@0 257 static void vertex_proc(struct vertex *vert)
nuclear@0 258 {
nuclear@0 259 vec4_t pview, pclip;
nuclear@0 260
nuclear@0 261 float *mvmat = st.matrix[MGL_MODELVIEW][st.mtop[MGL_MODELVIEW]];
nuclear@0 262 float *pmat = st.matrix[MGL_PROJECTION][st.mtop[MGL_PROJECTION]];
nuclear@0 263
nuclear@0 264 /* modelview transformation */
nuclear@0 265 transform(&pview, &vert->pos, mvmat);
nuclear@0 266
nuclear@0 267 if(st.flags & MGL_LIGHTING) {
nuclear@0 268 if((st.flags & MGL_SMOOTH) || st.vidx == 0) {
nuclear@0 269 int i;
nuclear@0 270 vec3_t norm;
nuclear@0 271 float irrad = 0.0f;
nuclear@0 272
nuclear@0 273 transform3(&norm, &vert->norm, mvmat);
nuclear@0 274
nuclear@0 275 for(i=0; i<MAX_LIGHTS; i++) {
nuclear@0 276 if(st.lint[i] > 1e-6f) {
nuclear@0 277 float ndotl = DOT(norm, st.ldir[i]);
nuclear@0 278 if(ndotl < 0.0) {
nuclear@0 279 ndotl = 0.0;
nuclear@0 280 }
nuclear@0 281 irrad += ndotl * st.lint[i];
nuclear@0 282 }
nuclear@0 283 }
nuclear@0 284 vert->energy = irrad;
nuclear@0 285 } else {
nuclear@0 286 vert->energy = st.v[0].energy;
nuclear@0 287 }
nuclear@0 288 }
nuclear@0 289
nuclear@0 290 transform(&pclip, &pview, pmat);
nuclear@0 291 /* TODO clipping in homogenous clip space */
nuclear@0 292
nuclear@0 293 if(pclip.w < 1e-6 && pclip.w > -1e-6) {
nuclear@0 294 vert->pos.x = vert->pos.y = vert->pos.z = vert->pos.w = 0.0f;
nuclear@0 295 return;
nuclear@0 296 }
nuclear@0 297
nuclear@0 298 /* perspective division */
nuclear@0 299 vert->pos.x = pclip.x / pclip.w;
nuclear@0 300 vert->pos.y = pclip.y / pclip.w;
nuclear@0 301 vert->pos.z = pclip.z / pclip.w;
nuclear@0 302 vert->pos.w = pclip.w;
nuclear@0 303
nuclear@0 304 /* viewport transformation */
nuclear@0 305 vert->pos.x = st.vp[0] + st.vp[2] * (vert->pos.x * 0.5 + 0.5);
nuclear@0 306 vert->pos.y = st.vp[1] + st.vp[3] * (-vert->pos.y * 0.5 + 0.5);
nuclear@0 307 }
nuclear@0 308
nuclear@0 309 void mgl_viewport(int x, int y, int width, int height)
nuclear@0 310 {
nuclear@0 311 st.vp[0] = x;
nuclear@0 312 st.vp[1] = y;
nuclear@0 313 st.vp[2] = width;
nuclear@0 314 st.vp[3] = height;
nuclear@0 315 }
nuclear@0 316
nuclear@0 317 void mgl_matrix_mode(int mmode)
nuclear@0 318 {
nuclear@0 319 st.mmode = mmode;
nuclear@0 320 }
nuclear@0 321
nuclear@0 322 void mgl_push_matrix(void)
nuclear@0 323 {
nuclear@0 324 float *topmat;
nuclear@0 325 if(st.mtop[st.mmode] >= MATRIX_STACK_SIZE - 1) {
nuclear@0 326 fprintf(stderr, "mgl_push_matrix: stack overflow\n");
nuclear@0 327 abort();
nuclear@0 328 }
nuclear@0 329
nuclear@0 330 topmat = st.matrix[st.mmode][st.mtop[st.mmode]];
nuclear@0 331 memcpy(topmat + 16, topmat, 16 * sizeof *topmat);
nuclear@0 332 st.mmode++;
nuclear@0 333 }
nuclear@0 334
nuclear@0 335 void mgl_pop_matrix(void)
nuclear@0 336 {
nuclear@0 337 if(st.mtop[st.mmode] <= 0) {
nuclear@0 338 fprintf(stderr, "mgl_pop_matrix: stack underflow\n");
nuclear@0 339 abort();
nuclear@0 340 }
nuclear@0 341 st.mtop[st.mmode]--;
nuclear@0 342 }
nuclear@0 343
nuclear@0 344 void mgl_load_matrix(float *mat)
nuclear@0 345 {
nuclear@0 346 float *dest = st.matrix[st.mmode][st.mtop[st.mmode]];
nuclear@0 347 memcpy(dest, mat, 16 * sizeof *dest);
nuclear@0 348 }
nuclear@0 349
nuclear@0 350 #define M(i,j) (((j) << 2) + (i))
nuclear@0 351 void mgl_mult_matrix(float *m2)
nuclear@0 352 {
nuclear@0 353 int i, j;
nuclear@0 354 float m1[16];
nuclear@0 355 float *dest = st.matrix[st.mmode][st.mtop[st.mmode]];
nuclear@0 356
nuclear@0 357 memcpy(m1, dest, sizeof m1);
nuclear@0 358
nuclear@0 359 for(i=0; i<4; i++) {
nuclear@0 360 for(j=0; j<4; j++) {
nuclear@0 361 dest[M(i,j)] = m1[M(0,j)] * m2[M(i,0)] +
nuclear@0 362 m1[M(1,j)] * m2[M(i,1)] +
nuclear@0 363 m1[M(2,j)] * m2[M(i,2)] +
nuclear@0 364 m1[M(3,j)] * m2[M(i,3)];
nuclear@0 365 }
nuclear@0 366 }
nuclear@0 367 }
nuclear@0 368
nuclear@0 369 void mgl_load_identity(void)
nuclear@0 370 {
nuclear@0 371 static float id[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
nuclear@0 372 mgl_load_matrix((float*)id);
nuclear@0 373 }
nuclear@0 374
nuclear@0 375 void mgl_translate(float x, float y, float z)
nuclear@0 376 {
nuclear@0 377 float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
nuclear@0 378 xform[12] = x;
nuclear@0 379 xform[13] = y;
nuclear@0 380 xform[14] = z;
nuclear@0 381 mgl_mult_matrix(xform);
nuclear@0 382 }
nuclear@0 383
nuclear@0 384 void mgl_rotate(float deg, float x, float y, float z)
nuclear@0 385 {
nuclear@0 386 float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
nuclear@0 387
nuclear@0 388 float angle = M_PI * deg / 180.0f;
nuclear@0 389 float sina = sin(angle);
nuclear@0 390 float cosa = cos(angle);
nuclear@0 391 float one_minus_cosa = 1.0f - cosa;
nuclear@0 392 float nxsq = x * x;
nuclear@0 393 float nysq = y * y;
nuclear@0 394 float nzsq = z * z;
nuclear@0 395
nuclear@0 396 xform[0] = nxsq + (1.0f - nxsq) * cosa;
nuclear@0 397 xform[4] = x * y * one_minus_cosa - z * sina;
nuclear@0 398 xform[8] = x * z * one_minus_cosa + y * sina;
nuclear@0 399 xform[1] = x * y * one_minus_cosa + z * sina;
nuclear@0 400 xform[5] = nysq + (1.0 - nysq) * cosa;
nuclear@0 401 xform[9] = y * z * one_minus_cosa - x * sina;
nuclear@0 402 xform[2] = x * z * one_minus_cosa - y * sina;
nuclear@0 403 xform[6] = y * z * one_minus_cosa + x * sina;
nuclear@0 404 xform[10] = nzsq + (1.0 - nzsq) * cosa;
nuclear@0 405
nuclear@0 406 mgl_mult_matrix(xform);
nuclear@0 407 }
nuclear@0 408
nuclear@0 409 void mgl_scale(float x, float y, float z)
nuclear@0 410 {
nuclear@0 411 float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
nuclear@0 412 xform[0] = x;
nuclear@0 413 xform[5] = y;
nuclear@0 414 xform[10] = z;
nuclear@0 415 mgl_mult_matrix(xform);
nuclear@0 416 }
nuclear@0 417
nuclear@0 418 void gl_ortho(float left, float right, float bottom, float top, float nr, float fr)
nuclear@0 419 {
nuclear@0 420 float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
nuclear@0 421
nuclear@0 422 float dx = right - left;
nuclear@0 423 float dy = top - bottom;
nuclear@0 424 float dz = fr - nr;
nuclear@0 425
nuclear@0 426 float tx = -(right + left) / dx;
nuclear@0 427 float ty = -(top + bottom) / dy;
nuclear@0 428 float tz = -(fr + nr) / dz;
nuclear@0 429
nuclear@0 430 float sx = 2.0 / dx;
nuclear@0 431 float sy = 2.0 / dy;
nuclear@0 432 float sz = -2.0 / dz;
nuclear@0 433
nuclear@0 434 xform[0] = sx;
nuclear@0 435 xform[5] = sy;
nuclear@0 436 xform[10] = sz;
nuclear@0 437 xform[12] = tx;
nuclear@0 438 xform[13] = ty;
nuclear@0 439 xform[14] = tz;
nuclear@0 440
nuclear@0 441 mgl_mult_matrix(xform);
nuclear@0 442 }
nuclear@0 443
nuclear@0 444 void mgl_frustum(float left, float right, float bottom, float top, float nr, float fr)
nuclear@0 445 {
nuclear@0 446 float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
nuclear@0 447
nuclear@0 448 float dx = right - left;
nuclear@0 449 float dy = top - bottom;
nuclear@0 450 float dz = fr - nr;
nuclear@0 451
nuclear@0 452 float a = (right + left) / dx;
nuclear@0 453 float b = (top + bottom) / dy;
nuclear@0 454 float c = -(fr + nr) / dz;
nuclear@0 455 float d = -2.0 * fr * nr / dz;
nuclear@0 456
nuclear@0 457 xform[0] = 2.0 * nr / dx;
nuclear@0 458 xform[5] = 2.0 * nr / dy;
nuclear@0 459 xform[8] = a;
nuclear@0 460 xform[9] = b;
nuclear@0 461 xform[10] = c;
nuclear@0 462 xform[11] = -1.0f;
nuclear@0 463 xform[14] = d;
nuclear@0 464
nuclear@0 465 mgl_mult_matrix(xform);
nuclear@0 466 }
nuclear@0 467
nuclear@0 468 void mgl_perspective(float vfov, float aspect, float nr, float fr)
nuclear@0 469 {
nuclear@0 470 float vfov_rad = M_PI * vfov / 180.0;
nuclear@0 471 float x = nr * tan(vfov_rad / 2.0);
nuclear@0 472 mgl_frustum(-aspect * x, aspect * x, -x, x, nr, fr);
nuclear@0 473 }
nuclear@3 474
nuclear@3 475 void mgl_teximage(int width, int height, unsigned char *pixels)
nuclear@3 476 {
nuclear@3 477 st.tex.width = width;
nuclear@3 478 st.tex.height = height;
nuclear@3 479 st.tex.pixels = pixels;
nuclear@3 480
nuclear@3 481 if(calc_shiftmask(width, &st.tex.xshift, &st.tex.xmask) == -1 ||
nuclear@3 482 calc_shiftmask(height, &st.tex.yshift, &st.tex.ymask) == -1) {
nuclear@3 483 st.tex.pixels = 0;
nuclear@3 484 }
nuclear@3 485 }
nuclear@3 486
nuclear@3 487 #define MAX_SHIFT 12
nuclear@3 488 static int calc_shiftmask(int val, int *shiftp, unsigned int *maskp)
nuclear@3 489 {
nuclear@3 490 int i;
nuclear@3 491
nuclear@3 492 for(i=0; i<MAX_SHIFT; i++) {
nuclear@3 493 if((val >> i) == 1) {
nuclear@3 494 *shiftp = i;
nuclear@3 495 *maskp = ~(0xffff << i);
nuclear@3 496 return 0;
nuclear@3 497 }
nuclear@3 498 }
nuclear@3 499 return -1;
nuclear@3 500 }