nuclear@0: /*
nuclear@0: 256-color 3D graphics hack for real-mode DOS.
nuclear@0: Copyright (C) 2011  John Tsiombikas <nuclear@member.fsf.org>
nuclear@0: 
nuclear@0: This program is free software: you can redistribute it and/or modify
nuclear@0: it under the terms of the GNU General Public License as published by
nuclear@0: the Free Software Foundation, either version 3 of the License, or
nuclear@0: (at your option) any later version.
nuclear@0: 
nuclear@0: This program is distributed in the hope that it will be useful,
nuclear@0: but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@0: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
nuclear@0: GNU General Public License for more details.
nuclear@0: 
nuclear@0: You should have received a copy of the GNU General Public License
nuclear@0: along with this program.  If not, see <http://www.gnu.org/licenses/>.
nuclear@0: */
nuclear@0: static void SCAN_EDGE(struct vertex *v0, struct vertex *v1)
nuclear@0: {
nuclear@0: 	int i, start, end;
nuclear@0: 	float dx, dy, dfdx;
nuclear@0: #ifdef INTERP_DEPTH
nuclear@0: 	float z, dz, dfdz;
nuclear@0: #endif
nuclear@0: #ifdef INTERP_ENERGY
nuclear@0: 	float e, de, dfde;
nuclear@0: #endif
nuclear@3: #ifdef INTERP_TEX
nuclear@3: 	float u, v, du, dv, dfdu, dfdv;
nuclear@3: #endif
nuclear@3: 	float x;
nuclear@0: 	struct vertex *edge;
nuclear@0: 
nuclear@0: 	dy = v1->pos.y - v0->pos.y;
nuclear@0: 	if(dy < 1e-6 && dy > -1e-6) {
nuclear@0: 		return;
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	dx = v1->pos.x - v0->pos.x;
nuclear@0: 	dfdx = dx / dy;
nuclear@0: 
nuclear@0: #ifdef INTERP_DEPTH
nuclear@0: 	dz = v1->pos.z - v0->pos.z;
nuclear@0: 	dfdz = dz / dy;
nuclear@0: #endif
nuclear@0: #ifdef INTERP_ENERGY
nuclear@0: 	de = v1->energy - v0->energy;
nuclear@0: 	dfde = de / dy;
nuclear@0: #endif
nuclear@3: #ifdef INTERP_TEX
nuclear@3: 	du = v1->tc.x - v0->tc.x;
nuclear@3: 	dv = v1->tc.y - v0->tc.y;
nuclear@3: 	dfdu = du / dy;
nuclear@3: 	dfdv = dv / dy;
nuclear@3: #endif
nuclear@0: 
nuclear@0: 	if(dy < 0.0) {
nuclear@0: 		struct vertex *tmp = v0;
nuclear@0: 		v0 = v1;
nuclear@0: 		v1 = tmp;
nuclear@0: 		edge = (st->ord == MGL_CCW) ? vright : vleft;
nuclear@0: 	} else {
nuclear@0: 		edge = (st->ord == MGL_CCW) ? vleft : vright;
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	start = (int)ROUND(v0->pos.y);
nuclear@0: 	end = (int)ROUND(v1->pos.y);
nuclear@0: 
nuclear@9: 	if(start >= 0) {
nuclear@9: 
nuclear@9: 		x = v0->pos.x;
nuclear@0: #ifdef INTERP_DEPTH
nuclear@9: 		z = v0->pos.z;
nuclear@0: #endif
nuclear@0: #ifdef INTERP_ENERGY
nuclear@9: 		e = v0->energy;
nuclear@0: #endif
nuclear@3: #ifdef INTERP_TEX
nuclear@9: 		u = v0->tc.x;
nuclear@9: 		v = v0->tc.y;
nuclear@3: #endif
nuclear@9: 	} else {
nuclear@9: 		float lines = -v0->pos.y;
nuclear@9: 
nuclear@9: 		x = v0->pos.x + dfdx * lines;
nuclear@9: #ifdef INTERP_DEPTH
nuclear@9: 		z = v0->pos.z + dfdz * lines;
nuclear@9: #endif
nuclear@9: #ifdef INTERP_ENERGY
nuclear@9: 		e = v0->energy + dfde * lines;
nuclear@9: #endif
nuclear@9: #ifdef INTERP_TEX
nuclear@9: 		u = v0->tc.x + dfdu * lines;
nuclear@9: 		v = v0->tc.y + dfdv * lines;
nuclear@9: #endif
nuclear@9: 		start = 0;
nuclear@9: 	}
nuclear@9: 
nuclear@9: 	if(end >= fb->height) {
nuclear@9: 		end = fb->height - 1;
nuclear@9: 	}
nuclear@9: 
nuclear@9: 
nuclear@0: 	for(i=start; i<end; i++) {
nuclear@0: 		edge[i].pos.x = x;
nuclear@0: 		x += dfdx;
nuclear@0: 
nuclear@0: 		edge[i].cidx = v0->cidx;
nuclear@0: #ifdef INTERP_DEPTH
nuclear@0: 		edge[i].pos.z = z;
nuclear@0: 		z += dfdz;
nuclear@0: #endif
nuclear@0: 
nuclear@0: #ifdef INTERP_ENERGY
nuclear@0: 		edge[i].energy = e;
nuclear@0: 		e += dfde;
nuclear@0: #else
nuclear@0: 		edge[i].energy = v0->energy;
nuclear@0: #endif
nuclear@3: 
nuclear@3: #ifdef INTERP_TEX
nuclear@3: 		edge[i].tc.x = u;
nuclear@3: 		edge[i].tc.y = v;
nuclear@3: 		u += dfdu;
nuclear@3: 		v += dfdv;
nuclear@3: #endif
nuclear@0: 	}
nuclear@0: }
nuclear@0: 
nuclear@0: static void SCAN_LINE(int y, unsigned char *sline)
nuclear@0: {
nuclear@3: 	int x0, x1, len, tmp, cidx;
nuclear@3: #if defined(INTERP_DEPTH) || defined(INTERP_ENERGY) || defined(INTERP_TEX)
nuclear@3: 	int i;
nuclear@0: 	float x, dx;
nuclear@0: #endif
nuclear@0: #ifdef INTERP_DEPTH
nuclear@0: 	float z, dz, dfdz;
nuclear@0: #endif
nuclear@0: #ifdef INTERP_ENERGY
nuclear@0: 	float e, de, dfde;
nuclear@0: #endif
nuclear@3: #ifdef INTERP_TEX
nuclear@17: 	unsigned int tx, ty;
nuclear@3: 	float u, v, du, dv, dfdu, dfdv;
nuclear@3: #endif
nuclear@0: 	struct vertex *left, *right;
nuclear@0: 
nuclear@0: 	x0 = (int)ROUND(vleft[y].pos.x);
nuclear@0: 	x1 = (int)ROUND(vright[y].pos.x);
nuclear@0: 
nuclear@0: 	if(x1 < x0) {
nuclear@0: 		if(st->flags & MGL_CULL_FACE) {
nuclear@0: 			return;
nuclear@0: 		}
nuclear@0: 		tmp = x0;
nuclear@0: 		x0 = x1;
nuclear@0: 		x1 = tmp;
nuclear@0: 
nuclear@0: 		left = vright;
nuclear@0: 		right = vleft;
nuclear@0: 	} else {
nuclear@0: 		left = vleft;
nuclear@0: 		right = vright;
nuclear@0: 	}
nuclear@0: 
nuclear@9: 	if(x1 >= fb->width) {
nuclear@9: 		x1 = fb->width - 1;
nuclear@9: 	}
nuclear@0: 
nuclear@0: 	cidx = left[y].cidx;
nuclear@3: #if !defined(INTERP_DEPTH) && !defined(INTERP_ENERGY) && !defined(INTERP_TEX)
nuclear@9: 	if(x0 < 0) x0 = 0;
nuclear@9: 	len = x1 - x0;
nuclear@9: 	assert(len >= 0);
nuclear@0: 	/* no interpolation at all, just memset the whole scanline */
nuclear@0: 	memset(sline + x0, cidx + left[y].energy * st->col_range, len);
nuclear@0: #else
nuclear@0: 	/* otherwise do a loop and interpolate whatever needs interpolating */
nuclear@0: 	x = left[y].pos.x;
nuclear@0: 	dx = right[y].pos.x - x;
nuclear@0: 
nuclear@0: 	if(dx < 0.5 && dx > -0.5) {
nuclear@0: 		return;
nuclear@0: 	}
nuclear@0: 
nuclear@9: 	if(x0 >= 0) {
nuclear@0: #ifdef INTERP_DEPTH
nuclear@9: 		z = left[y].pos.z;
nuclear@9: 		dz = right[y].pos.z - z;
nuclear@9: 		dfdz = dz / dx;
nuclear@0: #endif
nuclear@0: #ifdef INTERP_ENERGY
nuclear@9: 		e = left[y].energy;
nuclear@9: 		de = right[y].energy - e;
nuclear@9: 		dfde = de / dx;
nuclear@0: #endif
nuclear@3: #ifdef INTERP_TEX
nuclear@9: 		u = left[y].tc.x;
nuclear@9: 		v = left[y].tc.y;
nuclear@9: 		du = right[y].tc.x - u;
nuclear@9: 		dv = right[y].tc.y - v;
nuclear@9: 		dfdu = du / dx;
nuclear@9: 		dfdv = dv / dx;
nuclear@3: #endif
nuclear@9: 	} else {
nuclear@9: 		float dist = -left[y].pos.x;
nuclear@9: 
nuclear@9: #ifdef INTERP_DEPTH
nuclear@9: 		dz = right[y].pos.z - left[y].pos.z;
nuclear@9: 		dfdz = dz / dx;
nuclear@9: 		z = left[y].pos.z + dfdz * dist;
nuclear@9: #endif
nuclear@9: #ifdef INTERP_ENERGY
nuclear@9: 		de = right[y].energy - left[y].energy;
nuclear@9: 		dfde = de / dx;
nuclear@9: 		e = left[y].energy + dfde * dist;
nuclear@9: #endif
nuclear@9: #ifdef INTERP_TEX
nuclear@9: 		du = right[y].tc.x - left[y].tc.x;
nuclear@9: 		dv = right[y].tc.y - left[y].tc.y;
nuclear@9: 		dfdu = du / dx;
nuclear@9: 		dfdv = dv / dx;
nuclear@9: 		u = left[y].tc.x + dfdu * dist;
nuclear@9: 		v = left[y].tc.y + dfdv * dist;
nuclear@9: #endif
nuclear@9: 		x0 = 0;
nuclear@9: 	}
nuclear@9: 
nuclear@9: 	len = x1 - x0;
nuclear@0: 
nuclear@0: 	for(i=0; i<len; i++) {
nuclear@3: 		int c = cidx;
nuclear@3: 
nuclear@3: #ifdef INTERP_DEPTH
nuclear@10: 		long pix = (sline + x0 + i) - fb->pixels;
nuclear@9: 		unsigned short zval = (unsigned short)(z * USHRT_MAX);
nuclear@9: 		unsigned short *zptr = fb->zbuf[ZTILE(pix)] + ZTILE_OFFS(pix);
nuclear@9: 
nuclear@9: 		if(z < 0.0 || z >= 1.0 || zval > *zptr) {
nuclear@9: # ifdef INTERP_TEX
nuclear@9: 			u += dfdu;
nuclear@9: 			v += dfdv;
nuclear@9: # endif
nuclear@9: # ifdef INTERP_ENERGY
nuclear@9: 			e += dfde;
nuclear@9: # endif
nuclear@9: 			z += dfdz;
nuclear@9: 			continue;
nuclear@9: 		}
nuclear@9: 
nuclear@9: 		*zptr = zval;
nuclear@3: 		z += dfdz;
nuclear@3: #endif
nuclear@3: #ifdef INTERP_TEX
nuclear@17: 		tx = (unsigned int)(u * st->tex.width) & st->tex.xmask;
nuclear@17: 		ty = (unsigned int)(v * st->tex.height) & st->tex.ymask;
nuclear@3: 		c = st->tex.pixels[(ty << st->tex.xshift) + tx];
nuclear@3: 
nuclear@3: 		u += dfdu;
nuclear@3: 		v += dfdv;
nuclear@3: #endif
nuclear@0: #ifdef INTERP_ENERGY
nuclear@3: 		c += e * st->col_range;
nuclear@0: 		e += dfde;
nuclear@3: #else
nuclear@3: 		c += left[y].energy * st->col_range;
nuclear@0: #endif
nuclear@3: 		sline[x0 + i] = c;
nuclear@0: 	}
nuclear@0: #endif	/* flat */
nuclear@0: }