/*
  Copyright (C) 2010-2011  Charles Pence <charles@charlespence.net>
  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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "pch.h"
#include "quakedef.h"

extern    model_t    *loadmodel;

msurface_t    *warpface;

void BoundPoly (int numverts, float *verts, vec3_t mins, vec3_t maxs)
{
    int        i, j;
    float    *v;

    mins[0] = mins[1] = mins[2] = 9999;
    maxs[0] = maxs[1] = maxs[2] = -9999;
    v = verts;
    for (i=0 ; i<numverts ; i++)
        for (j=0 ; j<3 ; j++, v++)
        {
            if (*v < mins[j])
                mins[j] = *v;
            if (*v > maxs[j])
                maxs[j] = *v;
        }
}

void SubdividePolygon (int numverts, float *verts)
{
    int        i, j, k;
    vec3_t    mins, maxs;
    float    m;
    float    *v;
    vec3_t    front[64], back[64];
    int        f, b;
    float    dist[64];
    float    frac;
    glpoly_t    *poly;
    float    s, t;

    if (numverts > 60)
        Sys_Error ("numverts = %i", numverts);

    BoundPoly (numverts, verts, mins, maxs);

    for (i=0 ; i<3 ; i++)
    {
        m = (mins[i] + maxs[i]) * 0.5;
        m = Cvar_VariableValue("gl_subdivide_size") * 
            floor (m / Cvar_VariableValue("gl_subdivide_size") + 0.5);
        if (maxs[i] - m < 8)
            continue;
        if (m - mins[i] < 8)
            continue;

        // cut it
        v = verts + i;
        for (j=0 ; j<numverts ; j++, v+= 3)
            dist[j] = *v - m;

        // wrap cases
        dist[j] = dist[0];
        v-=i;
        VectorCopy (verts, v);

        f = b = 0;
        v = verts;
        for (j=0 ; j<numverts ; j++, v+= 3)
        {
            if (dist[j] >= 0)
            {
                VectorCopy (v, front[f]);
                f++;
            }
            if (dist[j] <= 0)
            {
                VectorCopy (v, back[b]);
                b++;
            }
            if (dist[j] == 0 || dist[j+1] == 0)
                continue;
            if ( (dist[j] > 0) != (dist[j+1] > 0) )
            {
                // clip point
                frac = dist[j] / (dist[j] - dist[j+1]);
                for (k=0 ; k<3 ; k++)
                    front[f][k] = back[b][k] = v[k] + frac*(v[3+k] - v[k]);
                f++;
                b++;
            }
        }

        SubdividePolygon (f, front[0]);
        SubdividePolygon (b, back[0]);
        return;
    }

    poly = (glpoly_t *)Hunk_Alloc (sizeof(glpoly_t) + (numverts-4) * VERTEXSIZE*sizeof(float));
    poly->next = warpface->polys;
    warpface->polys = poly;
    poly->numverts = numverts;
    for (i=0 ; i<numverts ; i++, verts+= 3)
    {
        VectorCopy (verts, poly->verts[i]);
        s = DotProduct (verts, warpface->texinfo->vecs[0]);
        t = DotProduct (verts, warpface->texinfo->vecs[1]);
        poly->verts[i][3] = s;
        poly->verts[i][4] = t;
    }
}

/*
================
GL_SubdivideSurface

Breaks a polygon up along axial 64 unit
boundaries so that turbulent and sky warps
can be done reasonably.
================
*/
void GL_SubdivideSurface (msurface_t *fa)
{
    vec3_t        verts[64];
    int            numverts;
    int            i;
    int            lindex;
    float        *vec;

    warpface = fa;

    //
    // convert edges back to a normal polygon
    //
    numverts = 0;
    for (i=0 ; i<fa->numedges ; i++)
    {
        lindex = loadmodel->surfedges[fa->firstedge + i];

        if (lindex > 0)
            vec = loadmodel->vertexes[loadmodel->edges[lindex].v[0]].position;
        else
            vec = loadmodel->vertexes[loadmodel->edges[-lindex].v[1]].position;
        VectorCopy (vec, verts[numverts]);
        numverts++;
    }

    SubdividePolygon (numverts, verts[0]);
}

//=========================================================



// speed up sin calculations - Ed
float    turbsin[] =
{
    #include "gl_warp_sin.h"
};
#define TURBSCALE (256.0 / (2 * M_PI))

/*
=============
EmitWaterPolys

Does a water warp on the pre-fragmented glpoly_t chain
=============
*/
void EmitWaterPolys (msurface_t *fa)
{
    glpoly_t    *p;
    float        *v;
    int            i;
    float        s, t, os, ot;


    for (p=fa->polys ; p ; p=p->next)
    {
        glBegin (GL_POLYGON);
        for (i=0,v=p->verts[0] ; i<p->numverts ; i++, v+=VERTEXSIZE)
        {
            os = v[3];
            ot = v[4];

            s = os + turbsin[(int)((ot*0.125+realtime) * TURBSCALE) & 255];
            s *= (1.0/64);

            t = ot + turbsin[(int)((os*0.125+realtime) * TURBSCALE) & 255];
            t *= (1.0/64);

            glTexCoord2f (s, t);
            glVertex3fv (v);
        }
        glEnd ();
    }
}


