/*
* Descent 3
* Copyright (C) 2024 Parallax Software
*
* 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/>.

--- HISTORICAL COMMENTS FOLLOW ---

 * $Logfile: /DescentIII/Main/editor/radiosity.h $
 * $Revision: 1.1.1.1 $
 * $Date: 2003-08-26 03:57:38 $
 * $Author: kevinb $
 *
 * Header for radiosity.cpp
 *
 * $Log: not supported by cvs2svn $
 *
 * 33    3/10/99 7:12p Jason
 * added smooth specular shading for curved surfaces
 *
 * 32    8/10/98 11:25a Jason
 * added better specular lighting
 *
 * 31    6/02/98 6:04p Jason
 * added specular lightmaps
 *
 * 30    5/22/98 3:28p Jason
 * added specular lighting
 *
 * 29    5/20/98 5:44p Jason
 * incremental checkin for bumpmapping
 *
 * 28    5/19/98 2:36p Jason
 * improved volume light casting
 *
 * 27    5/15/98 5:41p Jason
 * implemented volume lighting system
 *
 * 26    3/11/98 5:14p Jason
 * incremental lighting checkin
 *
 * 25    3/06/98 3:23p Jason
 * added lighting from satellites to indoor rooms
 *
 * 24    2/05/98 4:20p Matt
 * Fixed terrain lighting broken in roomnum/cellnum change
 *
 * 23    2/04/98 6:23p Matt
 * Changed object room number to indicate a terrain cell via a flag.  Got
 * rid of the object flag which used to indicate terrain.
 *
 */

#ifndef RADIOSITY_H
#define RADIOSITY_H

#include "pserror.h"
#include "pstypes.h"
#include "3d.h"
#include "gr.h"

// Shooting methods
#define SM_HEMICUBE 0
#define SM_RAYCAST 1
// This method makes a switch from RAYCAST to HEMICUBE after all satellites have
// been used for lightsources
#define SM_SWITCH_AFTER_SATELLITES 2

#define MAX_VOLUME_ELEMENTS 500

struct spectra {
  float r, g, b;
};

// element flags
#define EF_IGNORE 1
#define EF_SMALL 2 // Don't blend this one into the lightmap - it will corrupt!

struct rad_element {
  vector *verts;
  spectra exitance;
  float area;
  uint8_t num_verts;
  uint8_t flags; // see above
};

#define VEF_REVERSE_SHOOT 1

struct volume_element {
  spectra color;
  vector pos;
  uint8_t flags;
};

#define ST_ROOM 0           // This is a room surface
#define ST_TERRAIN 1        // This is a terrain surface
#define ST_SATELLITE 2      // This is a sun on the terrain
#define ST_PORTAL 3         // This surface is a portal, don't consider it
#define ST_ROOM_OBJECT 4    // This surface is part of an object
#define ST_TERRAIN_OBJECT 5 // This surface is part of terrain object
#define ST_EXTERNAL_ROOM 6  // This surface is a room outside

#define SF_TOUCHES_TERRAIN 1
#define SF_LIGHTSOURCE 2

struct rad_surface {
  float area;
  spectra emittance;
  spectra exitance;
  float reflectivity;  // how much light bounces off
  uint8_t xresolution; // how many elements (resolution x resolution) for this face
  uint8_t yresolution;
  rad_element *elements; // list of elements for this surface
  vector normal;         // normal of this surface
  vector *verts;

  uint8_t surface_type; // See ST_ types above

  int facenum; // facenumber of room
  int roomnum; // The roomnumber or terrain segment number
  uint8_t num_verts;
  uint8_t flags;

  float surface_area, element_area;

  uint8_t x1, y1, x2, y2; // Where in the lightmap our bounds are
};

struct rad_point {
  vector pos;
  uint8_t code;
};

extern float *Room_strongest_value[][4];

extern int Ignore_terrain;
extern int Ignore_satellites;

extern float Ignore_limit;
extern float rad_TotalFlux;
extern float rad_Convergence;

extern int rad_StepCount;
extern int rad_MaxStep;
extern int rad_DoneCalculating;

extern float rad_TotalUnsent;

extern rad_surface *rad_MaxSurface;

extern int rad_NumSurfaces;
extern int rad_NumElements;

extern float *rad_FormFactors;
extern rad_surface *rad_Surfaces;
extern volume_element *Volume_elements[];

extern int UseVolumeLights;
extern int Calculate_specular_lighting;

extern int Shoot_from_patch;

// Tells radiosity renderer to do volume lighting
extern int Do_volume_lighting;

int DoRadiosityRun(int method, rad_surface *light_surfaces, int count);
// Sets up our radiosity run
void InitRadiosityRun();

// Initializes the exitances for all surfaces
void InitExitance();

// Gets the spectral emittance for a surface
void GetEmittance(rad_surface *surf, spectra *dest);

// Sets all the elements of a surface to their initial exitance values
void SetExitanceForSurface(rad_surface *surf);

// Find the surface we want to shoot from
void UpdateUnsentValues();

// Does one iteration of ray-casting radiosity
int DoRadiosityIteration();

// Finds the world coordinate center of a element
void GetCenterOfElement(rad_element *ep, vector *dest);

// Finds the world coordinate center of a surface
void GetCenterOfSurface(rad_surface *ep, vector *dest);

// Returns 1 if a src vector can hit dest vector unobstructed
int ShootRayFromPoint(vector *src, vector *dest, rad_surface *src_surf, rad_surface *dest_surf);

// Shoots a ray from the center of the max surface to center of every other element
// Also updates the exitances of elements that get hit

void ShootMaxSurface();

// Does all the radiosity calculations until done
void CalculateRadiosity();

// returns the amount of unsent flux from a surface
float GetUnsentFlux(rad_surface *surface);

// Shuts down the radiosity stuff, freeing memory, etc
void CloseRadiosityRun();

// Initalizes memory for form factors
void SetupFormFactors();

// Calculates the area of the surfaces and elements in our environment
void CalculateArea();

// Counts the total number of elements we have to work with
void CountElements();

// Returns max color
float GetMaxColor(spectra *sp);

#endif