/*
--------------------------------------------------------------------------------
This source file is part of SkyX.
Visit http://www.paradise-studios.net/products/skyx/

Copyright (C) 2009-2012 Xavier Verguín González <xavyiy@gmail.com>

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser 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, or go to
http://www.gnu.org/copyleft/lesser.txt.
--------------------------------------------------------------------------------
*/

#ifdef GL_ES
precision highp int;
precision highp float;
#endif

// --------------------- SkyX skydome material ------------------------
// ------------------------ GLSL Fragment -----------------------------
#define USE_OGRE_FROM_FUTURE
#include <OgreUnifiedShader.h>

SAMPLER2D(uStarfield, 0);

OGRE_UNIFORMS(
uniform float uTime;
uniform vec3 uLightDir;
uniform float uG;
uniform float uG2;
uniform float uExposure;
)

MAIN_PARAMETERS
IN(vec2 vUV, TEXCOORD0)
IN(vec3 vRayleighColor, TEXCOORD1)
IN(vec3 vMieColor, TEXCOORD2)
IN(vec3 vDirection, TEXCOORD3)
IN(float vOpacity, TEXCOORD4)
IN(float vHeight, TEXCOORD5)
MAIN_DECLARATION
{
  float cos = dot(uLightDir, vDirection) / length(vDirection);
	float cos2 = cos * cos;
	
	float rayleighPhase = 0.75 * (1.0 + 0.5 * cos2);
	
	float miePhase = 1.5 * ((1.0 - uG2) / (2.0 + uG2)) * (1.0 + cos2) / pow(1.0 + uG2 - 2.0 * uG * cos, 1.5);

#ifdef LDR
	gl_FragColor = vec4((vec3_splat(1.0) - exp(vec3_splat(-uExposure) * (vec3_splat(rayleighPhase) * vRayleighColor + vec3_splat(miePhase) * vMieColor))), vOpacity);
#else // HDR
    gl_FragColor = vec4(vec3_splat(uExposure) * (vec3_splat(rayleighPhase) * vRayleighColor + vec3_splat(miePhase) * vMieColor), vOpacity);
#endif // LDR
	
	// For night rendering
	float nightmult = saturate(1.0 - max(gl_FragColor.x, max(gl_FragColor.y, gl_FragColor.z)) * 10.0);
	
#ifdef STARFIELD
	#ifdef LDR
		gl_FragColor.xyz += vec3_splat(nightmult) * (vec3(0.05, 0.05, 0.1) * vec3_splat(2.0 - 0.75 * saturate(-uLightDir.y)) * vec3_splat(pow(vHeight,3.0)) + texture2D(uStarfield, vUV + vec2_splat(uTime)).xyz * vec3_splat(0.35 + saturate(-uLightDir.y * 0.45))); 
	#else // HDR (Linear pipeline -> Gamma correction)
		gl_FragColor.xyz += vec3_splat(nightmult) * (vec3(0.05, 0.05, 0.1) * vec3_splat(2.0 - 0.75 * saturate(-uLightDir.y)) * vec3_splat(pow(vHeight,3.0)) + texture2D(uStarfield, vUV + vec2_splat(uTime)).xyz * vec3_splat(0.35 + saturate(-uLightDir.y * 0.45))); 
  #endif // LDR
#else // NO STARFIELD
	#ifdef LDR
		gl_FragColor.xyz += vec3_splat(nightmult) * (vec3(0.05, 0.05, 0.1) * vec3_splat(2.0 - 0.75 * saturate(-uLightDir.y)) * vec3_splat(pow(vHeight, 3.0))); 
	#else // HDR (Linear pipeline -> Gamma correction)
		gl_FragColor.xyz += vec3_splat(nightmult) * (vec3(0.05, 0.05, 0.1) * vec3_splat(2.0 - 0.75 * saturate(-uLightDir.y)) * vec3_splat(pow(vHeight, 3.0)));
	#endif // LDR
#endif // STARFIELD	
}