/*
Copyright (C) 1996-2001 Id Software, Inc.
Copyright (C) 2002-2009 John Fitzgibbons and others
Copyright (C) 2010-2014 QuakeSpasm developers
Copyright (C) 2020-2021 Vittorio Romeo

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 -- warping animation support

#include <GL/glew.h>

#include "quakeglm_qvec3.hpp"
#include "quakeglm_qvec3_togl.hpp"
#include "sbar.hpp"
#include "mathlib.hpp"
#include "cvar.hpp"
#include "client.hpp"
#include "glquake.hpp"
#include "sys.hpp"
#include "screen.hpp"
#include "gl_texmgr.hpp"
#include "draw.hpp"

extern cvar_t r_drawflat;

// TODO VR: (P1) oldwater 0 is broken
cvar_t r_oldwater = {"r_oldwater", "1", CVAR_ARCHIVE};
cvar_t r_waterquality = {"r_waterquality", "8", CVAR_NONE};
cvar_t r_waterwarp = {"r_waterwarp", "1", CVAR_NONE};

int gl_warpimagesize;
float load_subdivide_size; // johnfitz -- remember what subdivide_size value was
                           // when this map was loaded

float turbsin[] = {
#include "gl_warp_sin.hpp"
};

#define WARPCALC(s, t)                                                  \
    ((s + turbsin[(int)((t * 2) + (cl.time * (128.0 / M_PI))) & 255]) * \
        (1.0 / 64)) // johnfitz -- correct warp
#define WARPCALC2(s, t)                                                   \
    ((s + turbsin[(int)((t * 0.125 + cl.time) * (128.0 / M_PI)) & 255]) * \
        (1.0 / 64)) // johnfitz -- old warp

//==============================================================================
//
//  OLD-STYLE WATER
//
//==============================================================================

extern qmodel_t* loadmodel;

msurface_t* warpface;

cvar_t gl_subdivide_size = {"gl_subdivide_size", "128", CVAR_ARCHIVE};

void BoundPoly(int numverts, qfloat* verts, qvec3& mins, qvec3& maxs)
{
    int i;
    int j;
    qfloat* v;

    mins[0] = mins[1] = mins[2] = FLT_MAX;
    maxs[0] = maxs[1] = maxs[2] = -FLT_MAX;
    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, qfloat* verts)
{
    int i;
    int j;
    int k;
    qvec3 mins;
    qvec3 maxs;
    qfloat m;
    qfloat* v;
    qvec3 front[64];
    qvec3 back[64];
    int f;
    int b;
    qfloat dist[64];
    qfloat frac;
    glpoly_t* poly;
    qfloat s;
    qfloat 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 = gl_subdivide_size.value * floor(m / gl_subdivide_size.value + 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, toGlVec(front[0]));
        SubdividePolygon(b, toGlVec(back[0]));
        return;
    }

    poly = (glpoly_t*)Hunk_Alloc(
        sizeof(glpoly_t) + (numverts - 4) * VERTEXSIZE * sizeof(float));
    poly->next = warpface->polys->next;
    warpface->polys->next = 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
================
*/
void GL_SubdivideSurface(msurface_t* fa)
{
    qvec3 verts[64];
    int i;

    warpface = fa;

    // the first poly in the chain is the undivided poly for newwater rendering.
    // grab the verts from that.
    for(i = 0; i < fa->polys->numverts; i++)
        VectorCopy(fa->polys->verts[i], verts[i]);

    SubdividePolygon(fa->polys->numverts, toGlVec(verts[0]));
}

/*
================
DrawWaterPoly -- johnfitz
================
*/
void DrawWaterPoly(glpoly_t* p)
{
    float* v;
    int i;

    if(load_subdivide_size > 48)
    {
        glBegin(GL_POLYGON);
        v = p->verts[0];
        for(i = 0; i < p->numverts; i++, v += VERTEXSIZE)
        {
            glTexCoord2f(WARPCALC2(v[3], v[4]), WARPCALC2(v[4], v[3]));
            glVertex3fv(v);
        }
        glEnd();
    }
    else
    {
        glBegin(GL_POLYGON);
        v = p->verts[0];
        for(i = 0; i < p->numverts; i++, v += VERTEXSIZE)
        {
            glTexCoord2f(WARPCALC(v[3], v[4]), WARPCALC(v[4], v[3]));
            glVertex3fv(v);
        }
        glEnd();
    }
}

//==============================================================================
//
//  RENDER-TO-FRAMEBUFFER WATER
//
//==============================================================================

/*
=============
R_UpdateWarpTextures -- johnfitz -- each frame, update warping textures
=============
*/
void R_UpdateWarpTextures()
{
    texture_t* tx;
    int i;
    float x;
    float y;
    float x2;
    float warptess;

    if(r_oldwater.value || cl.paused || r_drawflat_cheatsafe ||
        r_lightmap_cheatsafe)
    {
        return;
    }

    warptess = 128.0 / CLAMP(3.0, floor(r_waterquality.value), 64.0);

    for(i = 0; i < cl.worldmodel->numtextures; i++)
    {
        if(!(tx = cl.worldmodel->textures[i]))
        {
            continue;
        }

        if(!tx->update_warp)
        {
            continue;
        }

        // render warp
        GL_SetCanvas(CANVAS_WARPIMAGE);
        GL_Bind(tx->gltexture);
        for(x = 0.0; x < 128.0; x = x2)
        {
            x2 = x + warptess;
            glBegin(GL_TRIANGLE_STRIP);
            for(y = 0.0; y < 128.01; y += warptess) // .01 for rounding errors
            {
                glTexCoord2f(WARPCALC(x, y), WARPCALC(y, x));
                glVertex2f(x, y);
                glTexCoord2f(WARPCALC(x2, y), WARPCALC(y, x2));
                glVertex2f(x2, y);
            }
            glEnd();
        }

        // copy to texture
        GL_Bind(tx->warpimage);
        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, glx,
            gly + glheight - gl_warpimagesize, gl_warpimagesize,
            gl_warpimagesize);

        tx->update_warp = false;
    }

    // ericw -- workaround for osx 10.6 driver bug when using FSAA. R_Clear only
    // clears the warpimage part of the screen.
    GL_SetCanvas(CANVAS_DEFAULT);

    // if warp render went down into sbar territory, we need to be sure to
    // refresh it next frame
    if(gl_warpimagesize + sb_lines > glheight)
    {
        Sbar_Changed();
    }

    // if viewsize is less than 100, we need to redraw the frame around the
    // viewport
    scr_tileclear_updates = 0;
}
