/** 
 * @file softenLightF.glsl
 *
 * $LicenseInfo:firstyear=2007&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2007, Linden Research, Inc.
 * 
 * This library 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;
 * version 2.1 of the License only.
 * 
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */
 
#extension GL_ARB_texture_rectangle : enable

#ifdef DEFINE_GL_FRAGCOLOR
out vec4 frag_color;
#else
#define frag_color gl_FragColor
#endif

uniform sampler2DRect diffuseRect;
uniform sampler2DRect specularRect;
uniform sampler2DRect positionMap;
uniform sampler2DRect normalMap;
uniform sampler2DRect lightMap;
uniform sampler2DRect depthMap;
uniform samplerCube environmentMap;
uniform sampler2D	  lightFunc;

uniform float blur_size;
uniform float blur_fidelity;

// Inputs
uniform vec4 morphFactor;
uniform vec3 camPosLocal;
//uniform vec4 camPosWorld;
uniform vec4 gamma;
uniform vec4 lightnorm;
uniform vec4 sunlight_color;
uniform vec4 ambient;
uniform vec4 blue_horizon;
uniform vec4 blue_density;
uniform float haze_horizon;
uniform float haze_density;
uniform float cloud_shadow;
uniform float density_multiplier;
uniform float distance_multiplier;
uniform float max_y;
uniform vec4 glow;
uniform float scene_light_strength;
uniform mat3 env_mat;
uniform mat3 ssao_effect_mat;

uniform vec3 sun_dir;
VARYING vec2 vary_fragcoord;

vec3 vary_PositionEye;

vec3 vary_SunlitColor;
vec3 vary_AmblitColor;
vec3 vary_AdditiveColor;
vec3 vary_AtmosAttenuation;

uniform mat4 inv_proj;
uniform vec2 screen_res;

vec4 getPosition_d(vec2 pos_screen, float depth)
{
	vec2 sc = pos_screen.xy*2.0;
	sc /= screen_res;
	sc -= vec2(1.0,1.0);
	vec4 ndc = vec4(sc.x, sc.y, 2.0*depth-1.0, 1.0);
	vec4 pos = inv_proj * ndc;
	pos /= pos.w;
	pos.w = 1.0;
	return pos;
}

vec4 getPosition(vec2 pos_screen)
{ //get position in screen space (world units) given window coordinate and depth map
	float depth = texture2DRect(depthMap, pos_screen.xy).a;
	return getPosition_d(pos_screen, depth);
}

vec3 getPositionEye()
{
	return vary_PositionEye;
}
vec3 getSunlitColor()
{
	return vary_SunlitColor;
}
vec3 getAmblitColor()
{
	return vary_AmblitColor;
}
vec3 getAdditiveColor()
{
	return vary_AdditiveColor;
}
vec3 getAtmosAttenuation()
{
	return vary_AtmosAttenuation;
}

void setPositionEye(vec3 v)
{
	vary_PositionEye = v;
}

void setSunlitColor(vec3 v)
{
	vary_SunlitColor = v;
}

void setAmblitColor(vec3 v)
{
	vary_AmblitColor = v;
}

void setAdditiveColor(vec3 v)
{
	vary_AdditiveColor = v;
}

void setAtmosAttenuation(vec3 v)
{
	vary_AtmosAttenuation = v;
}

void calcAtmospherics(vec3 inPositionEye, float ambFactor) {

	vec3 P = inPositionEye;
	setPositionEye(P);
	
	vec3 tmpLightnorm = lightnorm.xyz;

	vec3 Pn = normalize(P);
	float Plen = length(P);

	vec4 temp1 = vec4(0);
	vec3 temp2 = vec3(0);
	vec4 blue_weight;
	vec4 haze_weight;
	vec4 sunlight = sunlight_color;
	vec4 light_atten;

	//sunlight attenuation effect (hue and brightness) due to atmosphere
	//this is used later for sunlight modulation at various altitudes
	light_atten = (blue_density + vec4(haze_density * 0.25)) * (density_multiplier * max_y);
		//I had thought blue_density and haze_density should have equal weighting,
		//but attenuation due to haze_density tends to seem too strong

	temp1 = blue_density + vec4(haze_density);
	blue_weight = blue_density / temp1;
	haze_weight = vec4(haze_density) / temp1;

	//(TERRAIN) compute sunlight from lightnorm only (for short rays like terrain)
	temp2.y = max(0.0, tmpLightnorm.y);
	temp2.y = 1. / temp2.y;
	sunlight *= exp( - light_atten * temp2.y);

	// main atmospheric scattering line integral
	temp2.z = Plen * density_multiplier;

	// Transparency (-> temp1)
	// ATI Bugfix -- can't store temp1*temp2.z*distance_multiplier in a variable because the ati
	// compiler gets confused.
	temp1 = exp(-temp1 * temp2.z * distance_multiplier);

	//final atmosphere attenuation factor
	setAtmosAttenuation(temp1.rgb);
	
	//compute haze glow
	//(can use temp2.x as temp because we haven't used it yet)
	temp2.x = dot(Pn, tmpLightnorm.xyz);
	temp2.x = 1. - temp2.x;
		//temp2.x is 0 at the sun and increases away from sun
	temp2.x = max(temp2.x, .03);	//was glow.y
		//set a minimum "angle" (smaller glow.y allows tighter, brighter hotspot)
	temp2.x *= glow.x;
		//higher glow.x gives dimmer glow (because next step is 1 / "angle")
	temp2.x = pow(temp2.x, glow.z);
		//glow.z should be negative, so we're doing a sort of (1 / "angle") function

	//add "minimum anti-solar illumination"
	temp2.x += .25;
	
	//increase ambient when there are more clouds
	vec4 tmpAmbient = ambient + (vec4(1.) - ambient) * cloud_shadow * 0.5;
	
	/*  decrease value and saturation (that in HSV, not HSL) for occluded areas
	 * // for HSV color/geometry used here, see http://gimp-savvy.com/BOOK/index.html?node52.html
	 * // The following line of code performs the equivalent of:
	 * float ambAlpha = tmpAmbient.a;
	 * float ambValue = dot(vec3(tmpAmbient), vec3(0.577)); // projection onto <1/rt(3), 1/rt(3), 1/rt(3)>, the neutral white-black axis
	 * vec3 ambHueSat = vec3(tmpAmbient) - vec3(ambValue);
	 * tmpAmbient = vec4(RenderSSAOEffect.valueFactor * vec3(ambValue) + RenderSSAOEffect.saturationFactor *(1.0 - ambFactor) * ambHueSat, ambAlpha);
	 */
	tmpAmbient = vec4(mix(ssao_effect_mat * tmpAmbient.rgb, tmpAmbient.rgb, ambFactor), tmpAmbient.a);

	//haze color
	setAdditiveColor(
		vec3(blue_horizon * blue_weight * (sunlight*(1.-cloud_shadow) + tmpAmbient)
	  + (haze_horizon * haze_weight) * (sunlight*(1.-cloud_shadow) * temp2.x
		  + tmpAmbient)));

	//brightness of surface both sunlight and ambient
	setSunlitColor(vec3(sunlight * .5));
	setAmblitColor(vec3(tmpAmbient * .25));
	setAdditiveColor(getAdditiveColor() * vec3(1.0 - temp1));
}

vec3 atmosLighting(vec3 light)
{
	light *= getAtmosAttenuation().r;
	light += getAdditiveColor();
	return (2.0 * light);
}

vec3 atmosTransport(vec3 light) {
	light *= getAtmosAttenuation().r;
	light += getAdditiveColor() * 2.0;
	return light;
}
vec3 atmosGetDiffuseSunlightColor()
{
	return getSunlitColor();
}

vec3 scaleDownLight(vec3 light)
{
	return (light / scene_light_strength );
}

vec3 scaleUpLight(vec3 light)
{
	return (light * scene_light_strength);
}

vec3 atmosAmbient(vec3 light)
{
	return getAmblitColor() + light / 2.0;
}

vec3 atmosAffectDirectionalLight(float lightIntensity)
{
	return getSunlitColor() * lightIntensity;
}

vec3 scaleSoftClip(vec3 light)
{
	//soft clip effect:
	light = 1. - clamp(light, vec3(0.), vec3(1.));
	light = 1. - pow(light, gamma.xxx);

	return light;
}

void main() 
{
	vec2 tc = vary_fragcoord.xy;
	float depth = texture2DRect(depthMap, tc.xy).r;
	vec3 pos = getPosition_d(tc, depth).xyz;
	vec4 norm = texture2DRect(normalMap, tc);
	norm.xyz = (norm.xyz-0.5)*2.0; // unpack norm
		
	float da = max(dot(norm.xyz, sun_dir.xyz), 0.0);
	
	da = pow(da, 0.7);

	vec4 diffuse = texture2DRect(diffuseRect, tc);
	vec4 spec = texture2DRect(specularRect, vary_fragcoord.xy);
	
	vec3 col;
	float bloom = 0.0;
	if (diffuse.a < 0.9)
	{
		calcAtmospherics(pos.xyz, 1.0);
	
		col = atmosAmbient(vec3(0));
		col += atmosAffectDirectionalLight(max(min(da, 1.0), diffuse.a));
	
		col *= diffuse.rgb;
	
		if (spec.a > 0.0) // specular reflection
		{
			// the old infinite-sky shiny reflection
			//
			vec3 refnormpersp = normalize(reflect(pos.xyz, norm.xyz));
			float sa = dot(refnormpersp, sun_dir.xyz);
			vec3 dumbshiny = vary_SunlitColor*(texture2D(lightFunc, vec2(sa, spec.a)).r);
			
			// add the two types of shiny together
			vec3 spec_contrib = dumbshiny * spec.rgb;
			bloom = dot(spec_contrib, spec_contrib) / 4;
			col += spec_contrib;

			//add environmentmap
			vec3 env_vec = env_mat * refnormpersp;
			col = mix(col.rgb, textureCube(environmentMap, env_vec).rgb, 
				max(norm.a-diffuse.a*2.0, 0.0)); 
		}
	
		col = atmosLighting(col);
		col = scaleSoftClip(col);

		col = mix(col.rgb, diffuse.rgb, diffuse.a);
	}
	else
	{
		col = diffuse.rgb;
	}

	frag_color.rgb = col;

	frag_color.a = bloom;
}