/*
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 <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "3d.h"
#include "error.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"

#define GRID_MAX_SIZE   64
#define GRID_SCALE      i2f(2*20)
#define HEIGHT_SCALE    f1_0

int grid_w,grid_h;

g3s_uvl uvl_list1[] = { {0,0,0}, {f1_0,0,0},  {0,f1_0,0} };
g3s_uvl uvl_list2[] = { {f1_0,0,0}, {f1_0,f1_0,0},  {0,f1_0,0} };
g3s_lrgb lrgb_list1[] = { { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 } };
g3s_lrgb lrgb_list2[] = { { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 } };

ubyte *height_array;
ubyte *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) (((fix) LIGHT(_i,_j))<<8)

g3s_point save_row[GRID_MAX_SIZE];

vms_vector start_point;

grs_bitmap *terrain_bm;

int terrain_outline=0;

int org_i,org_j;

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


// LINT: adding function prototypes
void build_light_table(void);
void free_light_table(void);

// ------------------------------------------------------------------------
void draw_cell(int i,int j,g3s_point *p0,g3s_point *p1,g3s_point *p2,g3s_point *p3)
{
	g3s_point *pointlist[3];

	pointlist[0] = p0;
	pointlist[1] = p1;
	pointlist[2] = p3;
	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(3,pointlist,uvl_list1,lrgb_list1,terrain_bm,NULL,NULL);
	if (terrain_outline) {
		int lsave=Lighting_on;
		Lighting_on=0;
		gr_setcolor(BM_XRGB(31,0,0));
		g3_draw_line(pointlist[0],pointlist[1]);
		g3_draw_line(pointlist[2],pointlist[0]);
		Lighting_on=lsave;
	}

	pointlist[0] = p1;
	pointlist[1] = p2;
	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(3,pointlist,uvl_list2,lrgb_list2,terrain_bm,NULL,NULL);
	if (terrain_outline) {
		int lsave=Lighting_on;
		Lighting_on=0;
		gr_setcolor(BM_XRGB(31,0,0));
		g3_draw_line(pointlist[0],pointlist[1]);
		g3_draw_line(pointlist[1],pointlist[2]);
		g3_draw_line(pointlist[2],pointlist[0]);
		Lighting_on=lsave;
	}

	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) {
		render_mine(exit_segnum, 0, 0);
		//draw_exit_model();
		mine_tiles_drawn=-1;
		//if (ext_expl_playing)
		//	draw_fireball(&external_explosion);
	}

}

vms_vector y_cache[256];
ubyte yc_flags[256];

extern vms_matrix surface_orient;

vms_vector *get_dy_vec(int h)
{
	vms_vector *dyp;

	dyp = &y_cache[h];

	if (!yc_flags[h]) {
		vms_vector tv;

		//@@g3_rotate_delta_y(dyp,h*HEIGHT_SCALE);

		vm_vec_copy_scale(&tv,&surface_orient.uvec,h*HEIGHT_SCALE);
		g3_rotate_delta_vec(dyp,&tv);

		yc_flags[h] = 1;
	}

	return dyp;

}

int im=1;

void render_terrain(vms_vector *org_point,int org_2dx,int org_2dy)
{
	vms_vector delta_i,delta_j;		//delta_y;
	g3s_point p,last_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;
	vms_vector tv;

	mine_tiles_drawn = 0;	//clear flags

	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;

	memset(yc_flags,0,256);

	//Lighting_on = 0;
	Interpolation_method = im;

	vm_vec_copy_scale(&tv,&surface_orient.rvec,GRID_SCALE);
	g3_rotate_delta_vec(&delta_i,&tv);
	vm_vec_copy_scale(&tv,&surface_orient.fvec,GRID_SCALE);
	g3_rotate_delta_vec(&delta_j,&tv);

	vm_vec_scale_add(&start_point,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);

	vm_vec_sub(&tv,&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;

	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(low_i,j)));
		if (j==high_j)
			save_p_high = last_p;
		else
			g3_add_delta_vec(&last_p,&last_p,&delta_j);
	}

	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(i,j,&save_row[j],&save_row[j+1],&p2,&last_p2);

			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(i,j,&save_row[j],&save_row[j+1],&last_p2,&p2);

			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(i,j,&last_p2,&p2,&save_row[j+1],&save_row[j]);

			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(i,j,&p2,&last_p2,&save_row[j+1],&save_row[j]);

			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()
{
	if (height_array)
		d_free(height_array);
}

void load_terrain(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,BM_LINEAR,NULL);
	if (iff_error != IFF_NO_ERROR) {
		Error("File %s - IFF error: %s",filename,iff_errormsg(iff_error));
	}

	if (height_array)
		d_free(height_array);

	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 = height_bitmap.bm_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();
}


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;
}

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

fix get_face_light(vms_vector *p0,vms_vector *p1,vms_vector *p2)
{
	vms_vector norm;

	vm_vec_normal(&norm,p0,p1,p2);

	return -vm_vec_dot(&norm,&light);

}


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()
{
	if (light_array)
		d_free(light_array);

}

void build_light_table()
{
	int i,j;
	fix l,l2,min_l=0x7fffffff,max_l=0;


	if (light_array)
		d_free(light_array);

	MALLOC(light_array,ubyte,grid_w*grid_h);
	memset(light_array, 0, grid_w*grid_h);

	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;

		}
}