/*
 * 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.
 *
 */
// gl_warp.c -- sky and water polygons

#include "quakedef.h"

extern model_t *loadmodel;

extern msurface_t *skychain;
extern msurface_t **skychain_tail;

int           solidskytexture, alphaskytexture;
static float  speedscale, speedscale2; // for top sky and bottom sky

static msurface_t *warpface;

qboolean      r_skyboxloaded;

extern cvar_t gl_subdivide_size;

extern byte  *StringToRGB (char *s);

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, f, b;
    vec3_t        mins, maxs, front[64], back[64];
    float         m, *v, dist[64], frac, s, t, subdivide_size;
    glpoly_t     *poly;

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

    subdivide_size = max (1, gl_subdivide_size.value);
    BoundPoly (numverts, verts, mins, maxs);

    for (i = 0; i < 3; i++) {
        m = (mins[i] + maxs[i]) * 0.5;
        m = subdivide_size * floor (m / 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 = 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;
     * }
     */
    poly->midpoint[0] = poly->midpoint[1] = poly->midpoint[2] = 0;

    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;

        poly->midpoint[0] += poly->verts[i][0];
        poly->midpoint[1] += poly->verts[i][1];
        poly->midpoint[2] += poly->verts[i][2];
    }

    poly->midpoint[0] /= (float) numverts;
    poly->midpoint[1] /= (float) numverts;
    poly->midpoint[2] /= (float) numverts;

    poly->fxofs = (rand () % 64) - 64;
}

/*
 * 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, i, 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]);
}

// 

#define	TURBSINSIZE	128
#define	TURBSCALE	((float)TURBSINSIZE / (2 * M_PI))

byte          turbsin[TURBSINSIZE] = {
    127, 133, 139, 146, 152, 158, 164, 170, 176, 182, 187, 193, 198, 203, 208,
    213,
    217, 221, 226, 229, 233, 236, 239, 242, 245, 247, 249, 251, 252, 253, 254,
    254,
    255, 254, 254, 253, 252, 251, 249, 247, 245, 242, 239, 236, 233, 229, 226,
    221,
    217, 213, 208, 203, 198, 193, 187, 182, 176, 170, 164, 158, 152, 146, 139,
    133,
    127, 121, 115, 108, 102, 96, 90, 84, 78, 72, 67, 61, 56, 51, 46, 41,
    37, 33, 28, 25, 21, 18, 15, 12, 9, 7, 5, 3, 2, 1, 0, 0,
    0, 0, 0, 1, 2, 3, 5, 7, 9, 12, 15, 18, 21, 25, 28, 33,
    37, 41, 46, 51, 56, 61, 67, 72, 78, 84, 90, 96, 102, 108, 115, 121,
};

__inline static float SINTABLE_APPROX (float time) {
    float         sinlerpf, lerptime, lerp;
    int           sinlerp1, sinlerp2;

    sinlerpf = time * TURBSCALE;
    sinlerp1 = floor (sinlerpf);
    sinlerp2 = sinlerp1 + 1;
    lerptime = sinlerpf - sinlerp1;

    lerp = turbsin[sinlerp1 & (TURBSINSIZE - 1)] * (1 - lerptime) + turbsin[sinlerp2 & (TURBSINSIZE - 1)] * lerptime;
    return -8 + 16 * lerp / 255.0;
}

void EmitFlatPoly (msurface_t * fa) {
    glpoly_t     *p;
    float        *v;
    int           i;

    for (p = fa->polys; p; p = p->next) {
        glBegin (GL_POLYGON);
        for (i = 0, v = p->verts[0]; i < p->numverts; i++, v += VERTEXSIZE)
            glVertex3fv (v);
        glEnd ();
    }
}

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

    GL_DisableMultitexture ();
    GL_Bind (fa->texinfo->texture->gl_texturenum);

    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 + SINTABLE_APPROX (ot * 0.125 + cl.time);
            s *= (1.0 / 64);

            t = ot + SINTABLE_APPROX (os * 0.125 + cl.time);
            t *= (1.0 / 64);

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

/*
 * EmitSkyPolys
 */
void EmitSkyPolys (msurface_t * fa, qboolean mtex) {
    glpoly_t     *p;
    float        *v, s, t, ss = 0, tt = 0, length;
    int           i;
    vec3_t        dir;

    for (p = fa->polys; p; p = p->next) {
        glBegin (GL_POLYGON);
        for (i = 0, v = p->verts[0]; i < p->numverts; i++, v += VERTEXSIZE) {
            VectorSubtract (v, r_origin, dir);
            dir[2] *= 3;               // flatten the sphere

            length = VectorLength (dir);
            length = 6 * 63 / length;

            dir[0] *= length;
            dir[1] *= length;

            if (mtex) {
                s = (speedscale + dir[0]) * (1.0 / 128);
                t = (speedscale + dir[1]) * (1.0 / 128);

                ss = (speedscale2 + dir[0]) * (1.0 / 128);
                tt = (speedscale2 + dir[1]) * (1.0 / 128);
            } else {
                s = (speedscale + dir[0]) * (1.0 / 128);
                t = (speedscale + dir[1]) * (1.0 / 128);
            }

            if (mtex) {
                qglMultiTexCoord2f (GL_TEXTURE0_ARB, s, t);
                qglMultiTexCoord2f (GL_TEXTURE1_ARB, ss, tt);
            } else {
                glTexCoord2f (s, t);
            }

            glVertex3fv (v);
        }
        glEnd ();
    }
}

/*
 * R_DrawSkyChain
 */
void R_DrawSkyChain (void) {
    msurface_t   *fa;
    byte         *col;

    if (!skychain)
        return;

    GL_DisableMultitexture ();

    if (r_fastsky.value) {
        glDisable (GL_TEXTURE_2D);

        col = StringToRGB (r_skycolor.string);
        glColor3ubv (col);

        for (fa = skychain; fa; fa = fa->texturechain)
            EmitFlatPoly (fa);

        glEnable (GL_TEXTURE_2D);
        glColor3ubv (color_white);
    } else {
        if (gl_mtexable) {
            glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
            GL_Bind (solidskytexture);

            GL_EnableMultitexture ();
            glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
            GL_Bind (alphaskytexture);

            speedscale = cl.time * 8;
            speedscale -= (int) speedscale & ~127;
            speedscale2 = cl.time * 16;
            speedscale2 -= (int) speedscale2 & ~127;

            for (fa = skychain; fa; fa = fa->texturechain)
                EmitSkyPolys (fa, true);

            GL_DisableMultitexture ();
        } else {
            GL_Bind (solidskytexture);
            speedscale = cl.time * 8;
            speedscale -= (int) speedscale & ~127;

            for (fa = skychain; fa; fa = fa->texturechain)
                EmitSkyPolys (fa, false);

            glEnable (GL_BLEND);
            GL_Bind (alphaskytexture);
            speedscale = cl.time * 16;
            speedscale -= (int) speedscale & ~127;

            for (fa = skychain; fa; fa = fa->texturechain)
                EmitSkyPolys (fa, false);

            glDisable (GL_BLEND);
        }
    }

    skychain = NULL;
    skychain_tail = &skychain;
}

// 

/*
 * R_InitSky
 *
 * A sky texture is 256*128, with the right side being a masked overlay
 *
 */
void R_InitSky (miptex_t * mt) {
    int           i, j, p, r, g, b;
    byte         *src;
    unsigned      trans[128 * 128], transpix, *rgba;

    src = (byte *) mt + mt->offsets[0];

    // make an average value for the back to avoid a fringe on the top level
    r = g = b = 0;
    for (i = 0; i < 128; i++)
        for (j = 0; j < 128; j++) {
            p = src[i * 256 + j + 128];
            rgba = &d_8to24table[p];
            trans[(i * 128) + j] = *rgba;
            r += ((byte *) rgba)[0];
            g += ((byte *) rgba)[1];
            b += ((byte *) rgba)[2];
        }

    ((byte *) & transpix)[0] = r / (128 * 128);
    ((byte *) & transpix)[1] = g / (128 * 128);
    ((byte *) & transpix)[2] = b / (128 * 128);
    ((byte *) & transpix)[3] = 0;

    if (!solidskytexture)
        solidskytexture = texture_extension_number++;

    GL_Bind (solidskytexture);
    glTexImage2D (GL_TEXTURE_2D, 0, gl_solid_format, 128, 128, 0, GL_RGBA, GL_UNSIGNED_BYTE, trans);
    glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    for (i = 0; i < 128; i++)
        for (j = 0; j < 128; j++) {
            p = src[i * 256 + j];
            trans[(i * 128) + j] = p ? d_8to24table[p] : transpix;
        }

    if (!alphaskytexture)
        alphaskytexture = texture_extension_number++;

    GL_Bind (alphaskytexture);
    glTexImage2D (GL_TEXTURE_2D, 0, gl_alpha_format, 128, 128, 0, GL_RGBA, GL_UNSIGNED_BYTE, trans);
    glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
}

static char  *skybox_ext[6] = { "rt", "bk", "lf", "ft", "up", "dn" };

/*
 * R_SetSky
 */
int R_SetSky (char *skyname) {
    int           i, error = 0;
    byte         *data[6] = { NULL, NULL, NULL, NULL, NULL, NULL };

    for (i = 0; i < 6; i++) {
        if (!(data[i] = GL_LoadImagePixels (va ("env/%s%s", skyname, skybox_ext[i]), 0, 0, 0))
            && !(data[i] = GL_LoadImagePixels (va ("gfx/env/%s%s", skyname, skybox_ext[i]), 0, 0, 0))
            && !(data[i] = GL_LoadImagePixels (va ("env/%s_%s", skyname, skybox_ext[i]), 0, 0, 0))
            && !(data[i] = GL_LoadImagePixels (va ("gfx/env/%s_%s", skyname, skybox_ext[i]), 0, 0, 0))) {
            Con_Printf ("Couldn't load skybox \"%s\"\n", skyname);
            error = 1;

            goto cleanup;
        }
    }
    for (i = 0; i < 6; i++) {
        GL_Bind (skyboxtextures + i);
        GL_Upload32 ((unsigned int *) data[i], image_width, image_height, 0);
    }
    r_skyboxloaded = true;

  cleanup:
    for (i = 0; i < 6; i++) {
        if (data[i])
            Q_free (data[i]);
        else
            break;
    }

    return error;
}

qboolean OnChange_r_skybox (cvar_t * var, char *string) {
    if (!string[0]) {
        r_skyboxloaded = false;
        return false;
    }

    if (nehahra) {
        Cvar_SetValue (&r_oldsky, 0);
        Q_strncpyz (prev_skybox, string, sizeof (prev_skybox));
    }

    return R_SetSky (string);
}

static vec3_t skyclip[6] = {
    {1, 1, 0},
    {1, -1, 0},
    {0, -1, 1},
    {0, 1, 1},
    {1, 0, 1},
    {-1, 0, 1}
};

// 1 = s, 2 = t, 3 = 2048
static int    st_to_vec[6][3] = {
    {3, -1, 2},
    {-3, 1, 2},

    {1, 3, 2},
    {-1, -3, 2},

    {-2, -1, 3},                       // 0 degrees yaw, look straight up
    {2, -1, -3}                        // look straight down
};

// s = [0]/[2], t = [1]/[2]
static int    vec_to_st[6][3] = {
    {-2, 3, 1},
    {2, 3, -1},

    {1, 3, 2},
    {-1, 3, -2},

    {-2, -1, 3},
    {-2, 1, -3}
};

static float  skymins[2][6], skymaxs[2][6];

void DrawSkyPolygon (int nump, vec3_t vecs) {
    int           i, j, axis;
    float         s, t, dv, *vp;
    vec3_t        v, av;

    // decide which face it maps to
    VectorClear (v);
    for (i = 0, vp = vecs; i < nump; i++, vp += 3)
        VectorAdd (vp, v, v);
    av[0] = fabs (v[0]);
    av[1] = fabs (v[1]);
    av[2] = fabs (v[2]);
    if (av[0] > av[1] && av[0] > av[2])
        axis = (v[0] < 0) ? 1 : 0;
    else if (av[1] > av[2] && av[1] > av[0])
        axis = (v[1] < 0) ? 3 : 2;
    else
        axis = (v[2] < 0) ? 5 : 4;

    // project new texture coords
    for (i = 0; i < nump; i++, vecs += 3) {
        j = vec_to_st[axis][2];
        dv = (j > 0) ? vecs[j - 1] : -vecs[-j - 1];

        j = vec_to_st[axis][0];
        s = (j < 0) ? -vecs[-j - 1] / dv : vecs[j - 1] / dv;

        j = vec_to_st[axis][1];
        t = (j < 0) ? -vecs[-j - 1] / dv : vecs[j - 1] / dv;

        if (s < skymins[0][axis])
            skymins[0][axis] = s;
        if (t < skymins[1][axis])
            skymins[1][axis] = t;
        if (s > skymaxs[0][axis])
            skymaxs[0][axis] = s;
        if (t > skymaxs[1][axis])
            skymaxs[1][axis] = t;
    }
}

#define	MAX_CLIP_VERTS	64

void ClipSkyPolygon (int nump, vec3_t vecs, int stage) {
    float        *norm, *v, d, e, dists[MAX_CLIP_VERTS];
    qboolean      front, back;
    int           sides[MAX_CLIP_VERTS], newc[2], i, j;
    vec3_t        newv[2][MAX_CLIP_VERTS];

    if (nump > MAX_CLIP_VERTS - 2)
        Sys_Error ("ClipSkyPolygon: nump > MAX_CLIP_VERTS - 2");

    if (stage == 6) {                  // fully clipped, so draw it
        DrawSkyPolygon (nump, vecs);
        return;
    }

    front = back = false;
    norm = skyclip[stage];
    for (i = 0, v = vecs; i < nump; i++, v += 3) {
        d = DotProduct (v, norm);
        if (d > ON_EPSILON) {
            front = true;
            sides[i] = SIDE_FRONT;
        } else if (d < -ON_EPSILON) {
            back = true;
            sides[i] = SIDE_BACK;
        } else
            sides[i] = SIDE_ON;
        dists[i] = d;
    }

    if (!front || !back) {             // not clipped
        ClipSkyPolygon (nump, vecs, stage + 1);
        return;
    }
    // clip it
    sides[i] = sides[0];
    dists[i] = dists[0];
    VectorCopy (vecs, (vecs + (i * 3)));
    newc[0] = newc[1] = 0;

    for (i = 0, v = vecs; i < nump; i++, v += 3) {
        switch (sides[i]) {
            case SIDE_FRONT:
                VectorCopy (v, newv[0][newc[0]]);
                newc[0]++;
                break;

            case SIDE_BACK:
                VectorCopy (v, newv[1][newc[1]]);
                newc[1]++;
                break;

            case SIDE_ON:
                VectorCopy (v, newv[0][newc[0]]);
                newc[0]++;
                VectorCopy (v, newv[1][newc[1]]);
                newc[1]++;
                break;
        }

        if (sides[i] == SIDE_ON || sides[i + 1] == SIDE_ON || sides[i + 1] == sides[i])
            continue;

        d = dists[i] / (dists[i] - dists[i + 1]);
        for (j = 0; j < 3; j++) {
            e = v[j] + d * (v[j + 3] - v[j]);
            newv[0][newc[0]][j] = e;
            newv[1][newc[1]][j] = e;
        }
        newc[0]++;
        newc[1]++;
    }

    // continue
    ClipSkyPolygon (newc[0], newv[0][0], stage + 1);
    ClipSkyPolygon (newc[1], newv[1][0], stage + 1);
}

/*
 * R_AddSkyBoxSurface
 */
void R_AddSkyBoxSurface (msurface_t * fa) {
    int           i;
    vec3_t        verts[MAX_CLIP_VERTS];
    glpoly_t     *p;

    // calculate vertex values for sky box
    for (p = fa->polys; p; p = p->next) {
        for (i = 0; i < p->numverts; i++)
            VectorSubtract (p->verts[i], r_origin, verts[i]);
        ClipSkyPolygon (p->numverts, verts[0], 0);
    }
}

/*
 * R_ClearSkyBox
 */
void R_ClearSkyBox (void) {
    int           i;

    for (i = 0; i < 6; i++) {
        skymins[0][i] = skymins[1][i] = 9999;
        skymaxs[0][i] = skymaxs[1][i] = -9999;
    }
}

void MakeSkyVec (float s, float t, int axis) {
    int           j, k, farclip;
    vec3_t        v, b;

    farclip = max ((int) r_farclip.value, 4096);
    b[0] = s * (farclip >> 1);
    b[1] = t * (farclip >> 1);
    b[2] = (farclip >> 1);

    for (j = 0; j < 3; j++) {
        k = st_to_vec[axis][j];
        v[j] = (k < 0) ? -b[-k - 1] : b[k - 1];
        v[j] += r_origin[j];
    }

    // avoid bilerp seam
    s = (s + 1) * 0.5;
    t = (t + 1) * 0.5;

    if (s < 1.0 / 512)
        s = 1.0 / 512;
    else if (s > 511.0 / 512)
        s = 511.0 / 512;
    if (t < 1.0 / 512)
        t = 1.0 / 512;
    else if (t > 511.0 / 512)
        t = 511.0 / 512;

    t = 1.0 - t;
    glTexCoord2f (s, t);
    glVertex3fv (v);
}

static int    skytexorder[6] = { 0, 2, 1, 3, 4, 5 };

/*
 * R_DrawSkyBox
 */
void R_DrawSkyBox (void) {
    int           i;
    msurface_t   *fa;

    if (!skychain)
        return;

    R_ClearSkyBox ();
    for (fa = skychain; fa; fa = fa->texturechain)
        R_AddSkyBoxSurface (fa);

    GL_DisableMultitexture ();

    for (i = 0; i < 6; i++) {
        if (skymins[0][i] >= skymaxs[0][i] || skymins[1][i] >= skymaxs[1][i])
            continue;

        GL_Bind (skyboxtextures + skytexorder[i]);

        glBegin (GL_QUADS);
        MakeSkyVec (skymins[0][i], skymins[1][i], i);
        MakeSkyVec (skymins[0][i], skymaxs[1][i], i);
        MakeSkyVec (skymaxs[0][i], skymaxs[1][i], i);
        MakeSkyVec (skymaxs[0][i], skymins[1][i], i);
        glEnd ();
    }

    glDisable (GL_TEXTURE_2D);
    glColorMask (GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
    glEnable (GL_BLEND);
    glBlendFunc (GL_ZERO, GL_ONE);

    for (fa = skychain; fa; fa = fa->texturechain)
        EmitFlatPoly (fa);

    glEnable (GL_TEXTURE_2D);
    glColorMask (GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
    glDisable (GL_BLEND);
    glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    skychain = NULL;
    skychain_tail = &skychain;
}

void EmitCausticsPolys (void) {
    glpoly_t     *p;
    int           i;
    float        *v, s, t, os, ot;
    extern glpoly_t *caustics_polys;

    GL_Bind (underwatertexture);
    glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
    glEnable (GL_BLEND);
    glBlendFunc (GL_DST_COLOR, GL_SRC_COLOR);

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

            s = os + SINTABLE_APPROX (0.465 * (cl.time + ot));
            s *= -3 * (0.5 / 64);

            t = ot + SINTABLE_APPROX (0.465 * (cl.time + os));
            t *= -3 * (0.5 / 64);

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

    glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glDisable (GL_BLEND);

    caustics_polys = NULL;
}
