1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/mingl.c	Mon Nov 21 06:14:01 2011 +0200
     1.3 @@ -0,0 +1,466 @@
     1.4 +/*
     1.5 +256-color 3D graphics hack for real-mode DOS.
     1.6 +Copyright (C) 2011  John Tsiombikas <nuclear@member.fsf.org>
     1.7 +
     1.8 +This program is free software: you can redistribute it and/or modify
     1.9 +it under the terms of the GNU General Public License as published by
    1.10 +the Free Software Foundation, either version 3 of the License, or
    1.11 +(at your option) any later version.
    1.12 +
    1.13 +This program is distributed in the hope that it will be useful,
    1.14 +but WITHOUT ANY WARRANTY; without even the implied warranty of
    1.15 +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    1.16 +GNU General Public License for more details.
    1.17 +
    1.18 +You should have received a copy of the GNU General Public License
    1.19 +along with this program.  If not, see <http://www.gnu.org/licenses/>.
    1.20 +*/
    1.21 +#include <stdio.h>
    1.22 +#include <stdlib.h>
    1.23 +#include <string.h>
    1.24 +#include <math.h>
    1.25 +#include <assert.h>
    1.26 +#include "mingl.h"
    1.27 +#include "mglimpl.h"
    1.28 +
    1.29 +#define DOT(a, b)	((a).x * (b).x + (a).y * (b).y + (a).z * (b).z)
    1.30 +
    1.31 +static void transform(vec4_t *res, vec4_t *v, float *mat);
    1.32 +static void transform3(vec3_t *res, vec3_t *v, float *mat);
    1.33 +static void vertex_proc(struct vertex *vert);
    1.34 +
    1.35 +static struct state st;
    1.36 +static struct framebuffer fb;
    1.37 +
    1.38 +int mgl_init(int width, int height)
    1.39 +{
    1.40 +	int i;
    1.41 +
    1.42 +	st.flags = 0;
    1.43 +	st.mmode = 0;
    1.44 +
    1.45 +	mgl_front_face(MGL_CCW);
    1.46 +	mgl_cull_face(MGL_BACK);
    1.47 +
    1.48 +	st.curv.cidx = 0;
    1.49 +	st.curv.energy = 1.0;
    1.50 +	st.curv.norm.x = st.curv.norm.y = st.curv.norm.z = 0.0;
    1.51 +
    1.52 +	if(!(fb.pixels = malloc(width * height))) {
    1.53 +		return -1;
    1.54 +	}
    1.55 +	fb.width = width;
    1.56 +	fb.height = height;
    1.57 +	fb.zbuf = 0;
    1.58 +
    1.59 +	if(mgl_rast_init(&st, &fb) == -1) {
    1.60 +		free(fb.pixels);
    1.61 +		return -1;
    1.62 +	}
    1.63 +
    1.64 +	st.mtop[0] = st.mtop[1] = 0;
    1.65 +
    1.66 +	mgl_matrix_mode(MGL_MODELVIEW);
    1.67 +	mgl_load_identity();
    1.68 +	mgl_matrix_mode(MGL_PROJECTION);
    1.69 +	mgl_load_identity();
    1.70 +
    1.71 +	/* initial viewport in the size of the framebuffer */
    1.72 +	st.vp[0] = st.vp[1] = 0;
    1.73 +	st.vp[2] = width;
    1.74 +	st.vp[3] = height;
    1.75 +
    1.76 +	st.col_range = 256;
    1.77 +	for(i=0; i<MAX_LIGHTS; i++) {
    1.78 +		st.ldir[i].x = st.ldir[i].y = 0.0f;
    1.79 +		st.ldir[i].z = 1.0f;
    1.80 +		st.lint[i] = 0.0f;
    1.81 +	}
    1.82 +
    1.83 +	return 0;
    1.84 +}
    1.85 +
    1.86 +void mgl_free(void)
    1.87 +{
    1.88 +	mgl_rast_cleanup();
    1.89 +	free(fb.pixels);
    1.90 +}
    1.91 +
    1.92 +unsigned char *mgl_framebuffer(void)
    1.93 +{
    1.94 +	return fb.pixels;
    1.95 +}
    1.96 +
    1.97 +void mgl_clear(int cidx)
    1.98 +{
    1.99 +	memset(fb.pixels, cidx, fb.width * fb.height);
   1.100 +}
   1.101 +
   1.102 +void mgl_enable(unsigned int bit)
   1.103 +{
   1.104 +	st.flags |= bit;
   1.105 +}
   1.106 +
   1.107 +void mgl_disable(unsigned int bit)
   1.108 +{
   1.109 +	st.flags &= ~bit;
   1.110 +}
   1.111 +
   1.112 +void mgl_front_face(int ff)
   1.113 +{
   1.114 +	st.frontface = ff;
   1.115 +}
   1.116 +
   1.117 +void mgl_cull_face(int cf)
   1.118 +{
   1.119 +	st.cullface = cf;
   1.120 +}
   1.121 +
   1.122 +void mgl_color_range(int rng)
   1.123 +{
   1.124 +	st.col_range = rng;
   1.125 +}
   1.126 +
   1.127 +void mgl_light_intensity(int ltidx, float intens)
   1.128 +{
   1.129 +	assert(ltidx >= 0 && ltidx < MAX_LIGHTS);
   1.130 +	st.lint[ltidx] = intens;
   1.131 +}
   1.132 +
   1.133 +void mgl_light_direction(int ltidx, float x, float y, float z)
   1.134 +{
   1.135 +	vec3_t dir;
   1.136 +	float mag;
   1.137 +	assert(ltidx >= 0 && ltidx < MAX_LIGHTS);
   1.138 +
   1.139 +	dir.x = x;
   1.140 +	dir.y = y;
   1.141 +	dir.z = z;
   1.142 +	transform3(&st.ldir[ltidx], &dir, st.matrix[MGL_MODELVIEW][st.mtop[MGL_MODELVIEW]]);
   1.143 +
   1.144 +	mag = sqrt(DOT(st.ldir[ltidx], st.ldir[ltidx]));
   1.145 +	if(fabs(mag) < 1e-6) {
   1.146 +		mag = 1.0f;
   1.147 +	}
   1.148 +	st.ldir[ltidx].x /= mag;
   1.149 +	st.ldir[ltidx].y /= mag;
   1.150 +	st.ldir[ltidx].z /= mag;
   1.151 +}
   1.152 +
   1.153 +void mgl_begin(int prim)
   1.154 +{
   1.155 +	st.prim = prim;
   1.156 +	st.vidx = 0;
   1.157 +
   1.158 +	st.ord = st.frontface;
   1.159 +	if(st.cullface == MGL_FRONT) {
   1.160 +		st.ord = st.frontface == MGL_CCW ? MGL_CW : MGL_CCW;
   1.161 +	}
   1.162 +
   1.163 +	/* select the correct rasterizer according to state */
   1.164 +	mgl_rast_prepare();
   1.165 +}
   1.166 +
   1.167 +void mgl_end(void)
   1.168 +{
   1.169 +}
   1.170 +
   1.171 +void mgl_vertex2f(float x, float y)
   1.172 +{
   1.173 +	mgl_vertex4f(x, y, 0.0f, 1.0f);
   1.174 +}
   1.175 +
   1.176 +void mgl_vertex3f(float x, float y, float z)
   1.177 +{
   1.178 +	mgl_vertex4f(x, y, z, 1.0f);
   1.179 +}
   1.180 +
   1.181 +void mgl_vertex4f(float x, float y, float z, float w)
   1.182 +{
   1.183 +	st.v[st.vidx].pos.x = x;
   1.184 +	st.v[st.vidx].pos.y = y;
   1.185 +	st.v[st.vidx].pos.z = z;
   1.186 +	st.v[st.vidx].pos.w = w;
   1.187 +	st.v[st.vidx].cidx = st.curv.cidx;
   1.188 +	st.v[st.vidx].energy = st.curv.energy;
   1.189 +	st.v[st.vidx].norm = st.curv.norm;
   1.190 +	st.v[st.vidx].tc = st.curv.tc;
   1.191 +
   1.192 +	vertex_proc(st.v + st.vidx);
   1.193 +
   1.194 +	if(++st.vidx >= st.prim) {
   1.195 +		switch(st.prim) {
   1.196 +		case MGL_POINTS:
   1.197 +			mgl_draw_point(st.v);
   1.198 +			break;
   1.199 +		case MGL_LINES:
   1.200 +			mgl_draw_line(st.v, st.v + 1);
   1.201 +			break;
   1.202 +		case MGL_TRIANGLES:
   1.203 +		case MGL_QUADS:
   1.204 +			mgl_draw_poly(st.v, st.prim);
   1.205 +			break;
   1.206 +		default:
   1.207 +			fprintf(stderr, "invalid primitive: %d\n", st.prim);
   1.208 +			abort();
   1.209 +		}
   1.210 +		st.vidx = 0;
   1.211 +	}
   1.212 +}
   1.213 +
   1.214 +void mgl_color1f(float energy)
   1.215 +{
   1.216 +	st.curv.energy = energy;
   1.217 +}
   1.218 +
   1.219 +void mgl_index(int c)
   1.220 +{
   1.221 +	st.curv.cidx = c;
   1.222 +}
   1.223 +
   1.224 +void mgl_normal(float x, float y, float z)
   1.225 +{
   1.226 +	st.curv.norm.x = x;
   1.227 +	st.curv.norm.y = y;
   1.228 +	st.curv.norm.z = z;
   1.229 +}
   1.230 +
   1.231 +void mgl_texcoord2f(float x, float y)
   1.232 +{
   1.233 +	st.curv.tc.x = x;
   1.234 +	st.curv.tc.y = y;
   1.235 +}
   1.236 +
   1.237 +static void transform(vec4_t *res, vec4_t *v, float *mat)
   1.238 +{
   1.239 +	res->x = mat[0] * v->x + mat[4] * v->y + mat[8] * v->z + mat[12] * v->w;
   1.240 +	res->y = mat[1] * v->x + mat[5] * v->y + mat[9] * v->z + mat[13] * v->w;
   1.241 +	res->z = mat[2] * v->x + mat[6] * v->y + mat[10] * v->z + mat[14] * v->w;
   1.242 +	res->w = mat[3] * v->x + mat[7] * v->y + mat[11] * v->z + mat[15] * v->w;
   1.243 +}
   1.244 +
   1.245 +/* the matrix is 4x4 (16 floats), just ignoring anything out of the 3x3 */
   1.246 +static void transform3(vec3_t *res, vec3_t *v, float *mat)
   1.247 +{
   1.248 +	res->x = mat[0] * v->x + mat[4] * v->y + mat[8] * v->z;
   1.249 +	res->y = mat[1] * v->x + mat[5] * v->y + mat[9] * v->z;
   1.250 +	res->z = mat[2] * v->x + mat[6] * v->y + mat[10] * v->z;
   1.251 +}
   1.252 +
   1.253 +static void vertex_proc(struct vertex *vert)
   1.254 +{
   1.255 +	vec4_t pview, pclip;
   1.256 +
   1.257 +	float *mvmat = st.matrix[MGL_MODELVIEW][st.mtop[MGL_MODELVIEW]];
   1.258 +	float *pmat = st.matrix[MGL_PROJECTION][st.mtop[MGL_PROJECTION]];
   1.259 +
   1.260 +	/* modelview transformation */
   1.261 +	transform(&pview, &vert->pos, mvmat);
   1.262 +
   1.263 +	if(st.flags & MGL_LIGHTING) {
   1.264 +		if((st.flags & MGL_SMOOTH) || st.vidx == 0) {
   1.265 +			int i;
   1.266 +			vec3_t norm;
   1.267 +			float irrad = 0.0f;
   1.268 +
   1.269 +			transform3(&norm, &vert->norm, mvmat);
   1.270 +
   1.271 +			for(i=0; i<MAX_LIGHTS; i++) {
   1.272 +				if(st.lint[i] > 1e-6f) {
   1.273 +					float ndotl = DOT(norm, st.ldir[i]);
   1.274 +					if(ndotl < 0.0) {
   1.275 +						ndotl = 0.0;
   1.276 +					}
   1.277 +					irrad += ndotl * st.lint[i];
   1.278 +				}
   1.279 +			}
   1.280 +			vert->energy = irrad;
   1.281 +		} else {
   1.282 +			vert->energy = st.v[0].energy;
   1.283 +		}
   1.284 +	}
   1.285 +
   1.286 +	transform(&pclip, &pview, pmat);
   1.287 +	/* TODO clipping in homogenous clip space */
   1.288 +
   1.289 +	if(pclip.w < 1e-6 && pclip.w > -1e-6) {
   1.290 +		vert->pos.x = vert->pos.y = vert->pos.z = vert->pos.w = 0.0f;
   1.291 +		return;
   1.292 +	}
   1.293 +
   1.294 +	/* perspective division */
   1.295 +	vert->pos.x = pclip.x / pclip.w;
   1.296 +	vert->pos.y = pclip.y / pclip.w;
   1.297 +	vert->pos.z = pclip.z / pclip.w;
   1.298 +	vert->pos.w = pclip.w;
   1.299 +
   1.300 +	/* viewport transformation */
   1.301 +	vert->pos.x = st.vp[0] + st.vp[2] * (vert->pos.x * 0.5 + 0.5);
   1.302 +	vert->pos.y = st.vp[1] + st.vp[3] * (-vert->pos.y * 0.5 + 0.5);
   1.303 +}
   1.304 +
   1.305 +void mgl_viewport(int x, int y, int width, int height)
   1.306 +{
   1.307 +	st.vp[0] = x;
   1.308 +	st.vp[1] = y;
   1.309 +	st.vp[2] = width;
   1.310 +	st.vp[3] = height;
   1.311 +}
   1.312 +
   1.313 +void mgl_matrix_mode(int mmode)
   1.314 +{
   1.315 +	st.mmode = mmode;
   1.316 +}
   1.317 +
   1.318 +void mgl_push_matrix(void)
   1.319 +{
   1.320 +	float *topmat;
   1.321 +	if(st.mtop[st.mmode] >= MATRIX_STACK_SIZE - 1) {
   1.322 +		fprintf(stderr, "mgl_push_matrix: stack overflow\n");
   1.323 +		abort();
   1.324 +	}
   1.325 +
   1.326 +	topmat = st.matrix[st.mmode][st.mtop[st.mmode]];
   1.327 +	memcpy(topmat + 16, topmat, 16 * sizeof *topmat);
   1.328 +	st.mmode++;
   1.329 +}
   1.330 +
   1.331 +void mgl_pop_matrix(void)
   1.332 +{
   1.333 +	if(st.mtop[st.mmode] <= 0) {
   1.334 +		fprintf(stderr, "mgl_pop_matrix: stack underflow\n");
   1.335 +		abort();
   1.336 +	}
   1.337 +	st.mtop[st.mmode]--;
   1.338 +}
   1.339 +
   1.340 +void mgl_load_matrix(float *mat)
   1.341 +{
   1.342 +	float *dest = st.matrix[st.mmode][st.mtop[st.mmode]];
   1.343 +	memcpy(dest, mat, 16 * sizeof *dest);
   1.344 +}
   1.345 +
   1.346 +#define M(i,j)	(((j) << 2) + (i))
   1.347 +void mgl_mult_matrix(float *m2)
   1.348 +{
   1.349 +	int i, j;
   1.350 +	float m1[16];
   1.351 +	float *dest = st.matrix[st.mmode][st.mtop[st.mmode]];
   1.352 +
   1.353 +	memcpy(m1, dest, sizeof m1);
   1.354 +
   1.355 +	for(i=0; i<4; i++) {
   1.356 +		for(j=0; j<4; j++) {
   1.357 +			dest[M(i,j)] = m1[M(0,j)] * m2[M(i,0)] +
   1.358 +				m1[M(1,j)] * m2[M(i,1)] +
   1.359 +				m1[M(2,j)] * m2[M(i,2)] +
   1.360 +				m1[M(3,j)] * m2[M(i,3)];
   1.361 +		}
   1.362 +	}
   1.363 +}
   1.364 +
   1.365 +void mgl_load_identity(void)
   1.366 +{
   1.367 +	static float id[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
   1.368 +	mgl_load_matrix((float*)id);
   1.369 +}
   1.370 +
   1.371 +void mgl_translate(float x, float y, float z)
   1.372 +{
   1.373 +	float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
   1.374 +	xform[12] = x;
   1.375 +	xform[13] = y;
   1.376 +	xform[14] = z;
   1.377 +	mgl_mult_matrix(xform);
   1.378 +}
   1.379 +
   1.380 +void mgl_rotate(float deg, float x, float y, float z)
   1.381 +{
   1.382 +	float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
   1.383 +
   1.384 +	float angle = M_PI * deg / 180.0f;
   1.385 +	float sina = sin(angle);
   1.386 +	float cosa = cos(angle);
   1.387 +	float one_minus_cosa = 1.0f - cosa;
   1.388 +	float nxsq = x * x;
   1.389 +	float nysq = y * y;
   1.390 +	float nzsq = z * z;
   1.391 +
   1.392 +	xform[0] = nxsq + (1.0f - nxsq) * cosa;
   1.393 +	xform[4] = x * y * one_minus_cosa - z * sina;
   1.394 +	xform[8] = x * z * one_minus_cosa + y * sina;
   1.395 +	xform[1] = x * y * one_minus_cosa + z * sina;
   1.396 +	xform[5] = nysq + (1.0 - nysq) * cosa;
   1.397 +	xform[9] = y * z * one_minus_cosa - x * sina;
   1.398 +	xform[2] = x * z * one_minus_cosa - y * sina;
   1.399 +	xform[6] = y * z * one_minus_cosa + x * sina;
   1.400 +	xform[10] = nzsq + (1.0 - nzsq) * cosa;
   1.401 +
   1.402 +	mgl_mult_matrix(xform);
   1.403 +}
   1.404 +
   1.405 +void mgl_scale(float x, float y, float z)
   1.406 +{
   1.407 +	float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
   1.408 +	xform[0] = x;
   1.409 +	xform[5] = y;
   1.410 +	xform[10] = z;
   1.411 +	mgl_mult_matrix(xform);
   1.412 +}
   1.413 +
   1.414 +void gl_ortho(float left, float right, float bottom, float top, float nr, float fr)
   1.415 +{
   1.416 +	float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
   1.417 +
   1.418 +	float dx = right - left;
   1.419 +	float dy = top - bottom;
   1.420 +	float dz = fr - nr;
   1.421 +
   1.422 +	float tx = -(right + left) / dx;
   1.423 +	float ty = -(top + bottom) / dy;
   1.424 +	float tz = -(fr + nr) / dz;
   1.425 +
   1.426 +	float sx = 2.0 / dx;
   1.427 +	float sy = 2.0 / dy;
   1.428 +	float sz = -2.0 / dz;
   1.429 +
   1.430 +	xform[0] = sx;
   1.431 +	xform[5] = sy;
   1.432 +	xform[10] = sz;
   1.433 +	xform[12] = tx;
   1.434 +	xform[13] = ty;
   1.435 +	xform[14] = tz;
   1.436 +
   1.437 +	mgl_mult_matrix(xform);
   1.438 +}
   1.439 +
   1.440 +void mgl_frustum(float left, float right, float bottom, float top, float nr, float fr)
   1.441 +{
   1.442 +	float xform[] = {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
   1.443 +
   1.444 +	float dx = right - left;
   1.445 +	float dy = top - bottom;
   1.446 +	float dz = fr - nr;
   1.447 +
   1.448 +	float a = (right + left) / dx;
   1.449 +	float b = (top + bottom) / dy;
   1.450 +	float c = -(fr + nr) / dz;
   1.451 +	float d = -2.0 * fr * nr / dz;
   1.452 +
   1.453 +	xform[0] = 2.0 * nr / dx;
   1.454 +	xform[5] = 2.0 * nr / dy;
   1.455 +	xform[8] = a;
   1.456 +	xform[9] = b;
   1.457 +	xform[10] = c;
   1.458 +	xform[11] = -1.0f;
   1.459 +	xform[14] = d;
   1.460 +
   1.461 +	mgl_mult_matrix(xform);
   1.462 +}
   1.463 +
   1.464 +void mgl_perspective(float vfov, float aspect, float nr, float fr)
   1.465 +{
   1.466 +	float vfov_rad = M_PI * vfov / 180.0;
   1.467 +	float x = nr * tan(vfov_rad / 2.0);
   1.468 +	mgl_frustum(-aspect * x, aspect * x, -x, x, nr, fr);
   1.469 +}