source: orxonox.OLD/branches/atmospheric_engine/src/lib/graphics/effects/volfog_effect.cc @ 7768

/*
        orxonox - the future of 3D-vertical-scrollers

        Copyright (C) 2004 orx

        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, or (at your option)
        any later version.

### File Specific:
        main-programmer: hdavid, amaechler
*/

#include "volfog_effect.h"

#include "util/loading/load_param.h"
#include "util/loading/factory.h"

#include "p_node.h"
#include "state.h"

#include "glincl.h"
//#include "shell_command.h"

#define GLX_GLXEXT_PROTOTYPES
#include <GL/glx.h>
#include <GL/glut.h>

//#include <GL/glext.h> //OpenGL Extensions
//#include <GL/glxext.h> // GLX Extensions 

#ifndef GL_EXT_fog_coord
#define GL_EXT_fog_coord 1
typedef void (APIENTRY * PFNGLFOGCOORDFEXTPROC) (GLfloat coord);
typedef void (APIENTRY * PFNGLFOGCOORDFVEXTPROC) (const GLfloat *coord);
typedef void (APIENTRY * PFNGLFOGCOORDDEXTPROC) (GLdouble coord);
typedef void (APIENTRY * PFNGLFOGCOORDDVEXTPROC) (const GLdouble *coord);
typedef void (APIENTRY * PFNGLFOGCOORDPOINTEREXTPROC) (GLenum type, GLsizei stride, const GLvoid *pointer);
#endif

PFNGLFOGCOORDFEXTPROC glFogCoordfEXT = 0;
PFNGLFOGCOORDFVEXTPROC glFogCoordfvEXT = 0;
PFNGLFOGCOORDDEXTPROC glFogCoorddEXT = 0;
PFNGLFOGCOORDDVEXTPROC glFogCoorddvEXT = 0;
PFNGLFOGCOORDPOINTEREXTPROC glFogCoordPointerEXT = 0;


using namespace std;

CREATE_FACTORY(VolFogEffect, CL_VOLFOG_EFFECT);

VolFogEffect::VolFogEffect(const TiXmlElement* root)
{
        this->setClassID(CL_VOLFOG_EFFECT, "VolFogEffect");

        if (root != NULL)
                this->loadParams(root);

        // Initialize Effect
        this->init();

        // Activate Effect
        this->activate();
}


VolFogEffect::~VolFogEffect()
{
        this->deactivate();
}

void VolFogEffect::loadParams(const TiXmlElement* root)
{
        WeatherEffect::loadParams(root);
}

bool VolFogEffect::init()
{
        PRINTF(0)("Initalize VolFogEffect\n");

        // set fog mode
        GLenum fogMode  = GL_EXP;

        // set fog density
        float  fogDensity  = 0.001f;

        // set fog near & far distance
        float fogStart = 0.0f;
        float fogEnd   = 1000.0f;

        // Set fog color
        float fogColor[4] = {0.6f,0.58f,0.79f,0.0f};
        

        glFogCoordfEXT       = (PFNGLFOGCOORDFEXTPROC)glXGetProcAddressARB((const GLubyte*)"glFogCoordfEXT");
        glFogCoordfvEXT      = (PFNGLFOGCOORDFVEXTPROC)glXGetProcAddressARB((const GLubyte*)"glFogCoordfvEXT");
        glFogCoorddEXT       = (PFNGLFOGCOORDDEXTPROC)glXGetProcAddressARB((const GLubyte*)"glFogCoorddEXT");
        glFogCoorddvEXT      = (PFNGLFOGCOORDDVEXTPROC)glXGetProcAddressARB((const GLubyte*)"glFogCoorddvEXT");
        glFogCoordPointerEXT = (PFNGLFOGCOORDPOINTEREXTPROC)glXGetProcAddressARB((const GLubyte*)"glFogCoordPointerEXT");

        // set the fog attributes
        glFogf (GL_FOG_START,  fogStart);
        glFogf (GL_FOG_END,    fogEnd);
        glFogfv(GL_FOG_COLOR,  fogColor);
        glFogi (GL_FOG_MODE,   fogMode);
        glFogf (GL_FOG_DENSITY,fogDensity);
        glFogi (GL_FOG_COORDINATE_SOURCE_EXT,GL_FOG_COORDINATE_EXT);

        // enable the fog
        glEnable(GL_FOG);

        if (glewInit() == GLEW_OK)
                PRINTF(0)("glewInit OK\n");
        else
                PRINTF(0)("glewInit failed\n");

        if (glewGetExtension("GL_EXT_fog_coord"))
        {
                PRINTF(0)("GL_EXT_fog_coord extension found\n");
                return true;
        }
        else
        {
                PRINTF(0)("GL_EXT_fog_coord extension NOT found\n");
                return false;
        }
}


bool VolFogEffect::activate()
{
        PRINTF(0)("Activating VolFogEffect\n");
}

bool VolFogEffect::deactivate()
{
        PRINTF(0)("Deactivating VolFogEffect\n");

        glDisable(GL_FOG);
}


/**
* draws the effect, if needed
*/
void VolFogEffect::draw() const
{
  glPushAttrib(GL_ENABLE_BIT);
  glClearColor(fogColor[0],fogColor[1],fogColor[2],0.0f);
        glShadeModel(GL_SMOOTH);
        glEnable(GL_DEPTH_TEST);
        glEnable(GL_CULL_FACE);
        glCullFace(GL_BACK);

        /* clear all pixels in colour buffer */
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        /* Enable blending */
        //glEnable(GL_BLEND);
        //glBlendFunc(GL_SRC_ALPHA, GL_DST_ALPHA);
        
        int i;
        glLoadIdentity();

        
        glBegin( GL_LINES );
                glNormal3f(0,1,0);
                for(i=-20;i<=20;i+=2)
                {
                        float fog_c;
                        float diff[3];

                        diff[0] = State::getCameraNode()->getAbsCoor().x - i;
                        diff[2] = State::getCameraNode()->getAbsCoor().z + 20;
                        diff[1] = State::getCameraNode()->getAbsCoor().y;
                        fog_c = 1.3f*sqrt(diff[0]*diff[0]+diff[1]*diff[1]+diff[2]*diff[2]);
                        glFogCoordfEXT(fog_c*2);
                        glVertex3f(i,0,-20);

                        diff[0] = State::getCameraNode()->getAbsCoor().x - i;
                        diff[2] = State::getCameraNode()->getAbsCoor().z + 20;
                        diff[1] = State::getCameraNode()->getAbsCoor().y;
                        fog_c = 1.3f*sqrt(diff[0]*diff[0]+diff[1]*diff[1]+diff[2]*diff[2]);
                        glFogCoordfEXT(fog_c*2);
                        glVertex3f(i,0,20);

                        diff[0] = State::getCameraNode()->getAbsCoor().x - i;
                        diff[2] = State::getCameraNode()->getAbsCoor().z + 20;
                        diff[1] = State::getCameraNode()->getAbsCoor().y;
                        fog_c = 1.3f*sqrt(diff[0]*diff[0]+diff[1]*diff[1]+diff[2]*diff[2]);
                        glFogCoordfEXT(fog_c*2);
                        glVertex3f(-20,0,i);

                        diff[0] = State::getCameraNode()->getAbsCoor().x - i;
                        diff[2] = State::getCameraNode()->getAbsCoor().z + 20;
                        diff[1] = State::getCameraNode()->getAbsCoor().y;
                        fog_c = 1.3f*sqrt(diff[0]*diff[0]+diff[1]*diff[1]+diff[2]*diff[2]);
                        glFogCoordfEXT(fog_c*2);
                        glVertex3f(20,0,i);
                }
        glEnd();

  glPopAttrib();

}


/**
* ticks the effect if there is any time dependancy
*/
void VolFogEffect::tick(float dt)       
{
}