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/*

 * Portions of this file are copyright Rebirth contributors and licensed as

 * described in COPYING.txt.

 * Portions of this file are copyright Parallax Software and licensed

 * according to the Parallax license below.

 * See COPYING.txt for license details.

THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX

SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO

END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A

ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS

IN USING, DISPLAYING,  AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS

SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE

FREE PURPOSES.  IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE

CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES.  THE END-USER UNDERSTANDS

AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.

COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.

*/

/*

 *

 * Code to render cool external-scene terrain

 *

 */

#include <bitset>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "3d.h"

#include "dxxerror.h"

#include "gr.h"

#include "texmap.h"

#include "iff.h"

#include "u_mem.h"

#include "inferno.h"

#include "textures.h"

#include "object.h"

#include "endlevel.h"

#include "fireball.h"

#include "render.h"

#include "player.h"

#include "segment.h"

#include "terrain.h"

#include <memory>

#define GRID_MAX_SIZE   64

#define GRID_SCALE      i2f(2*20)

#define HEIGHT_SCALE    f1_0

static int grid_w,grid_h;

static RAIIdmem<ubyte[]> height_array;

static std::unique_ptr<uint8_t[]> light_array;

#define HEIGHT(_i,_j) (height_array[(_i)*grid_w+(_j)])

#define LIGHT(_i,_j) light_array[(_i)*grid_w+(_j)]

//!!#define HEIGHT(_i,_j)   height_array[(grid_h-1-j)*grid_w+(_i)]

//!!#define LIGHT(_i,_j)    light_array[(grid_h-1-j)*grid_w+(_i)]

#define LIGHTVAL(_i,_j) (static_cast<fix>(LIGHT(_i, _j)) << 8)

static grs_bitmap *terrain_bm;

static int terrain_outline=0;

static int org_i,org_j;

// LINT: adding function prototypes

static void build_light_table(void);

// ------------------------------------------------------------------------

static void draw_cell(grs_canvas &canvas, const vms_vector &Viewer_eye, const int i, const int j, cg3s_point &p0, cg3s_point &p1, cg3s_point &p2, cg3s_point &p3, int &mine_tiles_drawn)

{

        std::array<cg3s_point *, 3> pointlist;

        pointlist[0] = &p0;

        pointlist[1] = &p1;

        pointlist[2] = &p3;

        std::array<g3s_lrgb, 3> lrgb_list1;

        std::array<g3s_uvl, 3> uvl_list1;

        lrgb_list1[0].r = lrgb_list1[0].g = lrgb_list1[0].b = uvl_list1[0].l = LIGHTVAL(i,j);

        lrgb_list1[1].r = lrgb_list1[1].g = lrgb_list1[1].b = uvl_list1[1].l = LIGHTVAL(i,j+1);

        lrgb_list1[2].r = lrgb_list1[2].g = lrgb_list1[2].b = uvl_list1[2].l = LIGHTVAL(i+1,j);

        uvl_list1[0].u = (i)*f1_0/4; uvl_list1[0].v = (j)*f1_0/4;

        uvl_list1[1].u = (i)*f1_0/4; uvl_list1[1].v = (j+1)*f1_0/4;

        uvl_list1[2].u = (i+1)*f1_0/4;   uvl_list1[2].v = (j)*f1_0/4;

        g3_check_and_draw_tmap(canvas, pointlist, uvl_list1, lrgb_list1, *terrain_bm);

        if (terrain_outline) {

#if !DXX_USE_OGL

                const int lsave = Lighting_on;

                Lighting_on=0;

#endif

                const uint8_t color = BM_XRGB(31, 0, 0);

                g3_draw_line(canvas, *pointlist[0],*pointlist[1], color);

                g3_draw_line(canvas, *pointlist[2],*pointlist[0], color);

#if !DXX_USE_OGL

                Lighting_on=lsave;

#endif

        }

        pointlist[0] = &p1;

        pointlist[1] = &p2;

        std::array<g3s_uvl, 3> uvl_list2;

        std::array<g3s_lrgb, 3> lrgb_list2;

        lrgb_list2[0].r = lrgb_list2[0].g = lrgb_list2[0].b = uvl_list2[0].l = LIGHTVAL(i,j+1);

        lrgb_list2[1].r = lrgb_list2[1].g = lrgb_list2[1].b = uvl_list2[1].l = LIGHTVAL(i+1,j+1);

        lrgb_list2[2].r = lrgb_list2[2].g = lrgb_list2[2].b = uvl_list2[2].l = LIGHTVAL(i+1,j);

        uvl_list2[0].u = (i)*f1_0/4; uvl_list2[0].v = (j+1)*f1_0/4;

        uvl_list2[1].u = (i+1)*f1_0/4;   uvl_list2[1].v = (j+1)*f1_0/4;

        uvl_list2[2].u = (i+1)*f1_0/4;   uvl_list2[2].v = (j)*f1_0/4;

        g3_check_and_draw_tmap(canvas, pointlist, uvl_list2, lrgb_list2, *terrain_bm);

        if (terrain_outline) {

#if !DXX_USE_OGL

                const int lsave = Lighting_on;

                Lighting_on=0;

#endif

                const uint8_t color = BM_XRGB(31, 0, 0);

                g3_draw_line(canvas, *pointlist[0],*pointlist[1], color);

                g3_draw_line(canvas, *pointlist[1],*pointlist[2], color);

                g3_draw_line(canvas, *pointlist[2],*pointlist[0], color);

#if !DXX_USE_OGL

                Lighting_on=lsave;

#endif

        }

        if (i==org_i && j==org_j)

                mine_tiles_drawn |= 1;

        if (i==org_i-1 && j==org_j)

                mine_tiles_drawn |= 2;

        if (i==org_i && j==org_j-1)

                mine_tiles_drawn |= 4;

        if (i==org_i-1 && j==org_j-1)

                mine_tiles_drawn |= 8;

        if (mine_tiles_drawn == 0xf) {

                //draw_exit_model();

                mine_tiles_drawn=-1;

                window_rendered_data window;

                render_mine(canvas, Viewer_eye, PlayerUniqueEndlevelState.exit_segnum, 0, window);

                //if (ext_expl_playing)

                //      draw_fireball(&external_explosion);

        }

}

namespace {

class terrain_y_cache

{

        static const std::size_t cache_size = 256;

        std::bitset<cache_size> yc_flags;

        std::array<vms_vector, cache_size> y_cache;

public:

        vms_vector &operator()(uint_fast32_t h);

};

}

vms_vector &terrain_y_cache::operator()(uint_fast32_t h)

{

        auto &dyp = y_cache[h];

        if (auto &&ycf = yc_flags[h])

        {

        }

        else

        {

                ycf = 1;

                const auto tv = vm_vec_copy_scale(surface_orient.uvec,h*HEIGHT_SCALE);

                g3_rotate_delta_vec(dyp,tv);

        }

        return dyp;

}

void render_terrain(grs_canvas &canvas, const vms_vector &Viewer_eye, const vms_vector &org_point,int org_2dx,int org_2dy)

{

        vms_vector delta_i,delta_j;             //delta_y;

        g3s_point p,save_p_low,save_p_high;

        g3s_point last_p2;

        int i,j;

        int low_i,high_i,low_j,high_j;

        int viewer_i,viewer_j;

        org_i = org_2dy;

        org_j = org_2dx;

        low_i = 0;  high_i = grid_w-1;

        low_j = 0;  high_j = grid_h-1;

        //@@start_point.x = org_point->x - GRID_SCALE*(org_i - low_i);

        //@@start_point.z = org_point->z - GRID_SCALE*(org_j - low_j);

        //@@start_point.y = org_point->y;

        terrain_y_cache get_dy_vec;

#if !DXX_USE_OGL

        Interpolation_method = 1;

#endif

        {

        const auto tv = vm_vec_copy_scale(surface_orient.rvec,GRID_SCALE);

        g3_rotate_delta_vec(delta_i,tv);

        }

        {

        const auto tv = vm_vec_copy_scale(surface_orient.fvec,GRID_SCALE);

        g3_rotate_delta_vec(delta_j,tv);

        }

        auto start_point = vm_vec_scale_add(org_point,surface_orient.rvec,-(org_i - low_i)*GRID_SCALE);

        vm_vec_scale_add2(start_point,surface_orient.fvec,-(org_j - low_j)*GRID_SCALE);

        {

                const auto tv = vm_vec_sub(Viewer->pos,start_point);

        viewer_i = vm_vec_dot(tv,surface_orient.rvec) / GRID_SCALE;

        viewer_j = vm_vec_dot(tv,surface_orient.fvec) / GRID_SCALE;

        }

        auto last_p = g3_rotate_point(start_point);

        save_p_low = last_p;

        g3s_point save_row[GRID_MAX_SIZE]{};

        // Is this needed?

        for (j=low_j;j<=high_j;j++) {

                g3_add_delta_vec(save_row[j],last_p,get_dy_vec(HEIGHT(low_i,j)));

                if (j==high_j)

                        save_p_high = last_p;

                else

                        g3_add_delta_vec(last_p,last_p,delta_j);

        }

        int mine_tiles_drawn = 0;    //flags to tell if all 4 tiles under mine have drawn

        for (i=low_i;i<viewer_i;i++) {

                g3_add_delta_vec(save_p_low,save_p_low,delta_i);

                last_p = save_p_low;

                g3_add_delta_vec(last_p2,last_p,get_dy_vec(HEIGHT(i+1,low_j)));

                for (j=low_j;j<viewer_j;j++) {

                        g3s_point p2;

                        g3_add_delta_vec(p,last_p,delta_j);

                        g3_add_delta_vec(p2,p,get_dy_vec(HEIGHT(i+1,j+1)));

                        draw_cell(canvas, Viewer_eye, i, j, save_row[j], save_row[j+1], p2, last_p2, mine_tiles_drawn);

                        last_p = p;

                        save_row[j] = last_p2;

                        last_p2 = p2;

                }

                vm_vec_negate(delta_j);                 //don't have a delta sub...

                g3_add_delta_vec(save_p_high,save_p_high,delta_i);

                last_p = save_p_high;

                g3_add_delta_vec(last_p2,last_p,get_dy_vec(HEIGHT(i+1,high_j)));

                for (j=high_j-1;j>=viewer_j;j--) {

                        g3s_point p2;

                        g3_add_delta_vec(p,last_p,delta_j);

                        g3_add_delta_vec(p2,p,get_dy_vec(HEIGHT(i+1,j)));

                        draw_cell(canvas, Viewer_eye, i, j, save_row[j], save_row[j+1], last_p2, p2, mine_tiles_drawn);

                        last_p = p;

                        save_row[j+1] = last_p2;

                        last_p2 = p2;

                }

                save_row[j+1] = last_p2;

                vm_vec_negate(delta_j);         //restore sign of j

        }

        //now do i from other end

        vm_vec_negate(delta_i);         //going the other way now...

        //@@start_point.x += (high_i-low_i)*GRID_SCALE;

        vm_vec_scale_add2(start_point,surface_orient.rvec,(high_i-low_i)*GRID_SCALE);

        g3_rotate_point(last_p,start_point);

        save_p_low = last_p;

        for (j=low_j;j<=high_j;j++) {

                g3_add_delta_vec(save_row[j],last_p,get_dy_vec(HEIGHT(high_i,j)));

                if (j==high_j)

                        save_p_high = last_p;

                else

                        g3_add_delta_vec(last_p,last_p,delta_j);

        }

        for (i=high_i-1;i>=viewer_i;i--) {

                g3_add_delta_vec(save_p_low,save_p_low,delta_i);

                last_p = save_p_low;

                g3_add_delta_vec(last_p2,last_p,get_dy_vec(HEIGHT(i,low_j)));

                for (j=low_j;j<viewer_j;j++) {

                        g3s_point p2;

                        g3_add_delta_vec(p,last_p,delta_j);

                        g3_add_delta_vec(p2,p,get_dy_vec(HEIGHT(i,j+1)));

                        draw_cell(canvas, Viewer_eye, i, j, last_p2, p2, save_row[j+1], save_row[j], mine_tiles_drawn);

                        last_p = p;

                        save_row[j] = last_p2;

                        last_p2 = p2;

                }

                vm_vec_negate(delta_j);                 //don't have a delta sub...

                g3_add_delta_vec(save_p_high,save_p_high,delta_i);

                last_p = save_p_high;

                g3_add_delta_vec(last_p2,last_p,get_dy_vec(HEIGHT(i,high_j)));

                for (j=high_j-1;j>=viewer_j;j--) {

                        g3s_point p2;

                        g3_add_delta_vec(p,last_p,delta_j);

                        g3_add_delta_vec(p2,p,get_dy_vec(HEIGHT(i,j)));

                        draw_cell(canvas, Viewer_eye, i, j, p2, last_p2, save_row[j+1], save_row[j], mine_tiles_drawn);

                        last_p = p;

                        save_row[j+1] = last_p2;

                        last_p2 = p2;

                }

                save_row[j+1] = last_p2;

                vm_vec_negate(delta_j);         //restore sign of j

        }

}

void free_height_array()

{

        height_array.reset();

}

void load_terrain(const char *filename)

{

        grs_bitmap height_bitmap;

        int iff_error;

        int i,j;

        ubyte h,min_h,max_h;

        iff_error = iff_read_bitmap(filename, height_bitmap, NULL);

        if (iff_error != IFF_NO_ERROR) {

                Error("File %s - IFF error: %s",filename,iff_errormsg(iff_error));

        }

        grid_w = height_bitmap.bm_w;

        grid_h = height_bitmap.bm_h;

        Assert(grid_w <= GRID_MAX_SIZE);

        Assert(grid_h <= GRID_MAX_SIZE);

        height_array.reset(height_bitmap.get_bitmap_data());

        max_h=0; min_h=255;

        for (i=0;i<grid_w;i++)

                for (j=0;j<grid_h;j++) {

                        h = HEIGHT(i,j);

                        if (h > max_h)

                                max_h = h;

                        if (h < min_h)

                                min_h = h;

                }

        for (i=0;i<grid_w;i++)

                for (j=0;j<grid_h;j++)

                        HEIGHT(i,j) -= min_h;

//      d_free(height_bitmap.bm_data);

        terrain_bm = terrain_bitmap;

        build_light_table();

}

static void get_pnt(vms_vector &p,int i,int j)

{

        // added on 02/20/99 by adb to prevent overflow

        if (i >= grid_h) i = grid_h - 1;

        if (i == grid_h - 1 && j >= grid_w) j = grid_w - 1;

        // end additions by adb

        p.x = GRID_SCALE*i;

        p.z = GRID_SCALE*j;

        p.y = HEIGHT(i,j)*HEIGHT_SCALE;

}

constexpr vms_vector light{0x2e14,0xe8f5,0x5eb8};

static fix get_face_light(const vms_vector &p0,const vms_vector &p1,const vms_vector &p2)

{

        const auto norm = vm_vec_normal(p0,p1,p2);

        return -vm_vec_dot(norm,light);

}

static fix get_avg_light(int i,int j)

{

        vms_vector pp,p[6];

        fix sum;

        int f;

        get_pnt(pp,i,j);

        get_pnt(p[0],i-1,j);

        get_pnt(p[1],i,j-1);

        get_pnt(p[2],i+1,j-1);

        get_pnt(p[3],i+1,j);

        get_pnt(p[4],i,j+1);

        get_pnt(p[5],i-1,j+1);

        for (f=0,sum=0;f<6;f++)

                sum += get_face_light(pp,p[f],p[(f+1)%5]);

        return sum/6;

}

void free_light_table()

{

        light_array.reset();

}

static void build_light_table()

{

        std::size_t alloc = grid_w*grid_h;

        light_array = std::make_unique<uint8_t[]>(alloc);

        memset(light_array.get(), 0, alloc);

        int i,j;

        fix l, l2, min_l = INT32_MAX, max_l = 0;

        for (i=1;i<grid_w;i++)

                for (j=1;j<grid_h;j++) {

                        l = get_avg_light(i,j);

                        if (l > max_l)

                                max_l = l;

                        if (l < min_l)

                                min_l = l;

                }

        for (i=1;i<grid_w;i++)

                for (j=1;j<grid_h;j++) {

                        l = get_avg_light(i,j);

                        if (min_l == max_l) {

                                LIGHT(i,j) = l>>8;

                                continue;

                        }

                        l2 = fixdiv((l-min_l),(max_l-min_l));

                        if (l2==f1_0)

                                l2--;

                        LIGHT(i,j) = l2>>8;

                }

}