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

*/
// r_aclip.c: clip routines for drawing Alias models directly to the screen

#include "quakedef.h"
#include "r_local.h"
#include "d_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;
    }
}


#if	!id386

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;
        }
    }
}

#endif


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;
}


/*
================
R_AliasClipTriangle
================
*/
void R_AliasClipTriangle(mtriangle_t *ptri)
{
    int				i, k, pingpong;
    mtriangle_t		mtri;
    unsigned		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;
        // transparencies - begin
#if	id386
        if (!use_c_renderer)
            // transparencies - end
        {
            D_PolysetDraw();
        }
        // transparencies - begin
        else
#endif
            D_PolysetDraw_C();
        // transparencies - end
    }
}

