/*
	r_aclip.c

	clip routines for drawing Alias models directly to the screen

	Copyright (C) 1996-1997  Id Software, Inc.

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

	See the GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

	$Id$
*/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include "QF/render.h"

#include "d_local.h"
#include "r_local.h"

static finalvert_t fv[2][8];
static auxvert_t av[8];

void        R_AliasProjectFinalVert (finalvert_t *fv, auxvert_t *av);
void        R_Alias_clip_top (finalvert_t *pfv0, finalvert_t *pfv1,
							  finalvert_t *out);
void        R_Alias_clip_bottom (finalvert_t *pfv0, finalvert_t *pfv1,
								 finalvert_t *out);
void        R_Alias_clip_left (finalvert_t *pfv0, finalvert_t *pfv1,
							   finalvert_t *out);
void        R_Alias_clip_right (finalvert_t *pfv0, finalvert_t *pfv1,
								finalvert_t *out);


/*
	R_Alias_clip_z

	pfv0 is the unclipped vertex, pfv1 is the z-clipped vertex
*/
void
R_Alias_clip_z (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
	float       scale;
	auxvert_t  *pav0, *pav1, avout;

	pav0 = &av[pfv0 - &fv[0][0]];
	pav1 = &av[pfv1 - &fv[0][0]];

	if (pfv0->v[1] >= pfv1->v[1]) {
		scale = (ALIAS_Z_CLIP_PLANE - pav0->fv[2]) /
			(pav1->fv[2] - pav0->fv[2]);

		avout.fv[0] = pav0->fv[0] + (pav1->fv[0] - pav0->fv[0]) * scale;
		avout.fv[1] = pav0->fv[1] + (pav1->fv[1] - pav0->fv[1]) * scale;
		avout.fv[2] = ALIAS_Z_CLIP_PLANE;

		out->v[2] = pfv0->v[2] + (pfv1->v[2] - pfv0->v[2]) * scale;
		out->v[3] = pfv0->v[3] + (pfv1->v[3] - pfv0->v[3]) * scale;
		out->v[4] = pfv0->v[4] + (pfv1->v[4] - pfv0->v[4]) * scale;
	} else {
		scale = (ALIAS_Z_CLIP_PLANE - pav1->fv[2]) /
			(pav0->fv[2] - pav1->fv[2]);

		avout.fv[0] = pav1->fv[0] + (pav0->fv[0] - pav1->fv[0]) * scale;
		avout.fv[1] = pav1->fv[1] + (pav0->fv[1] - pav1->fv[1]) * scale;
		avout.fv[2] = ALIAS_Z_CLIP_PLANE;

		out->v[2] = pfv1->v[2] + (pfv0->v[2] - pfv1->v[2]) * scale;
		out->v[3] = pfv1->v[3] + (pfv0->v[3] - pfv1->v[3]) * scale;
		out->v[4] = pfv1->v[4] + (pfv0->v[4] - pfv1->v[4]) * scale;
	}

	R_AliasProjectFinalVert (out, &avout);

	if (out->v[0] < r_refdef.aliasvrect.x)
		out->flags |= ALIAS_LEFT_CLIP;
	if (out->v[1] < r_refdef.aliasvrect.y)
		out->flags |= ALIAS_TOP_CLIP;
	if (out->v[0] > r_refdef.aliasvrectright)
		out->flags |= ALIAS_RIGHT_CLIP;
	if (out->v[1] > r_refdef.aliasvrectbottom)
		out->flags |= ALIAS_BOTTOM_CLIP;
}

void
R_Alias_clip_left (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
	float       scale;
	int         i;

	if (pfv0->v[1] >= pfv1->v[1]) {
		scale = (float) (r_refdef.aliasvrect.x - pfv0->v[0]) /
			(pfv1->v[0] - pfv0->v[0]);
		for (i = 0; i < 6; i++)
			out->v[i] = pfv0->v[i] + (pfv1->v[i] - pfv0->v[i]) * scale + 0.5;
	} else {
		scale = (float) (r_refdef.aliasvrect.x - pfv1->v[0]) /
			(pfv0->v[0] - pfv1->v[0]);
		for (i = 0; i < 6; i++)
			out->v[i] = pfv1->v[i] + (pfv0->v[i] - pfv1->v[i]) * scale + 0.5;
	}
}

void
R_Alias_clip_right (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
	float       scale;
	int         i;

	if (pfv0->v[1] >= pfv1->v[1]) {
		scale = (float) (r_refdef.aliasvrectright - pfv0->v[0]) /
			(pfv1->v[0] - pfv0->v[0]);
		for (i = 0; i < 6; i++)
			out->v[i] = pfv0->v[i] + (pfv1->v[i] - pfv0->v[i]) * scale + 0.5;
	} else {
		scale = (float) (r_refdef.aliasvrectright - pfv1->v[0]) /
			(pfv0->v[0] - pfv1->v[0]);
		for (i = 0; i < 6; i++)
			out->v[i] = pfv1->v[i] + (pfv0->v[i] - pfv1->v[i]) * scale + 0.5;
	}
}

void
R_Alias_clip_top (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
	float       scale;
	int         i;

	if (pfv0->v[1] >= pfv1->v[1]) {
		scale = (float) (r_refdef.aliasvrect.y - pfv0->v[1]) /
			(pfv1->v[1] - pfv0->v[1]);
		for (i = 0; i < 6; i++)
			out->v[i] = pfv0->v[i] + (pfv1->v[i] - pfv0->v[i]) * scale + 0.5;
	} else {
		scale = (float) (r_refdef.aliasvrect.y - pfv1->v[1]) /
			(pfv0->v[1] - pfv1->v[1]);
		for (i = 0; i < 6; i++)
			out->v[i] = pfv1->v[i] + (pfv0->v[i] - pfv1->v[i]) * scale + 0.5;
	}
}

void
R_Alias_clip_bottom (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
	float       scale;
	int         i;

	if (pfv0->v[1] >= pfv1->v[1]) {
		scale = (float) (r_refdef.aliasvrectbottom - pfv0->v[1]) /
			(pfv1->v[1] - pfv0->v[1]);

		for (i = 0; i < 6; i++)
			out->v[i] = pfv0->v[i] + (pfv1->v[i] - pfv0->v[i]) * scale + 0.5;
	} else {
		scale = (float) (r_refdef.aliasvrectbottom - pfv1->v[1]) /
			(pfv0->v[1] - pfv1->v[1]);

		for (i = 0; i < 6; i++)
			out->v[i] = pfv1->v[i] + (pfv0->v[i] - pfv1->v[i]) * scale + 0.5;
	}
}

int
R_AliasClip (finalvert_t *in, finalvert_t *out, int flag, int count,
			 void (*clip) (finalvert_t *pfv0, finalvert_t *pfv1,
						   finalvert_t *out))
{
	int         i, j, k;
	int         flags, oldflags;

	j = count - 1;
	k = 0;
	for (i = 0; i < count; j = i, i++) {
		oldflags = in[j].flags & flag;
		flags = in[i].flags & flag;

		if (flags && oldflags)
			continue;
		if (oldflags ^ flags) {
			clip (&in[j], &in[i], &out[k]);
			out[k].flags = 0;
			if (out[k].v[0] < r_refdef.aliasvrect.x)
				out[k].flags |= ALIAS_LEFT_CLIP;
			if (out[k].v[1] < r_refdef.aliasvrect.y)
				out[k].flags |= ALIAS_TOP_CLIP;
			if (out[k].v[0] > r_refdef.aliasvrectright)
				out[k].flags |= ALIAS_RIGHT_CLIP;
			if (out[k].v[1] > r_refdef.aliasvrectbottom)
				out[k].flags |= ALIAS_BOTTOM_CLIP;
			k++;
		}
		if (!flags) {
			out[k] = in[i];
			k++;
		}
	}

	return k;
}

void
R_AliasClipTriangle (mtriangle_t *ptri)
{
	int         i, k, pingpong;
	mtriangle_t mtri;
	unsigned int clipflags;

	// copy vertexes and fix seam texture coordinates
	if (ptri->facesfront) {
		fv[0][0] = pfinalverts[ptri->vertindex[0]];
		fv[0][1] = pfinalverts[ptri->vertindex[1]];
		fv[0][2] = pfinalverts[ptri->vertindex[2]];
	} else {
		for (i = 0; i < 3; i++) {
			fv[0][i] = pfinalverts[ptri->vertindex[i]];

			if (!ptri->facesfront && (fv[0][i].flags & ALIAS_ONSEAM))
				fv[0][i].v[2] += r_affinetridesc.seamfixupX16;
		}
	}

	// clip
	clipflags = fv[0][0].flags | fv[0][1].flags | fv[0][2].flags;

	if (clipflags & ALIAS_Z_CLIP) {
		for (i = 0; i < 3; i++)
			av[i] = pauxverts[ptri->vertindex[i]];

		k = R_AliasClip (fv[0], fv[1], ALIAS_Z_CLIP, 3, R_Alias_clip_z);
		if (k == 0)
			return;

		pingpong = 1;
		clipflags = fv[1][0].flags | fv[1][1].flags | fv[1][2].flags;
	} else {
		pingpong = 0;
		k = 3;
	}

	if (clipflags & ALIAS_LEFT_CLIP) {
		k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
						 ALIAS_LEFT_CLIP, k, R_Alias_clip_left);
		if (k == 0)
			return;

		pingpong ^= 1;
	}

	if (clipflags & ALIAS_RIGHT_CLIP) {
		k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
						 ALIAS_RIGHT_CLIP, k, R_Alias_clip_right);
		if (k == 0)
			return;

		pingpong ^= 1;
	}

	if (clipflags & ALIAS_BOTTOM_CLIP) {
		k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
						 ALIAS_BOTTOM_CLIP, k, R_Alias_clip_bottom);
		if (k == 0)
			return;

		pingpong ^= 1;
	}

	if (clipflags & ALIAS_TOP_CLIP) {
		k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
						 ALIAS_TOP_CLIP, k, R_Alias_clip_top);
		if (k == 0)
			return;

		pingpong ^= 1;
	}

	for (i = 0; i < k; i++) {
		if (fv[pingpong][i].v[0] < r_refdef.aliasvrect.x)
			fv[pingpong][i].v[0] = r_refdef.aliasvrect.x;
		else if (fv[pingpong][i].v[0] > r_refdef.aliasvrectright)
			fv[pingpong][i].v[0] = r_refdef.aliasvrectright;

		if (fv[pingpong][i].v[1] < r_refdef.aliasvrect.y)
			fv[pingpong][i].v[1] = r_refdef.aliasvrect.y;
		else if (fv[pingpong][i].v[1] > r_refdef.aliasvrectbottom)
			fv[pingpong][i].v[1] = r_refdef.aliasvrectbottom;

		fv[pingpong][i].flags = 0;
	}

	// draw triangles
	mtri.facesfront = ptri->facesfront;
	r_affinetridesc.ptriangles = &mtri;
	r_affinetridesc.pfinalverts = fv[pingpong];

	// FIXME: do all at once as trifan?
	mtri.vertindex[0] = 0;
	for (i = 1; i < k - 1; i++) {
		mtri.vertindex[1] = i;
		mtri.vertindex[2] = i + 1;
		D_PolysetDraw ();
	}
}