// This shader is mostly an adaptation of the shader found at
//  http://www.bonzaisoftware.com/water_tut.html and its glsl conversion
//  available at http://forum.bonzaisoftware.com/viewthread.php?tid=10
//  © Michael Horsch - 2005

uniform sampler2D water_normalmap;
uniform sampler2D water_reflection;
uniform sampler2D water_dudvmap;
uniform float saturation;
uniform float RainNorm;

varying vec4 waterTex1; //moving texcoords
varying vec4 waterTex2; //moving texcoords
varying vec4 waterTex4; //viewts
varying vec4 ecPosition;
varying vec3 viewerdir;
varying vec3 lightdir;
varying vec3 normal;

void main(void)
{
const vec4 sca = vec4(0.005, 0.005, 0.005, 0.005);
const vec4 sca2 = vec4(0.02, 0.02, 0.02, 0.02);
const vec4 tscale = vec4(0.25, 0.25, 0.25, 0.25);

// compute direction to viewer
vec3 E = normalize(viewerdir);

// compute direction to light source
vec3 L = normalize(lightdir);

// half vector
vec3 H = normalize(L + E);
	
const float water_shininess = 240.0;

vec4 viewt = normalize(waterTex4);

vec4 disdis = texture2D(water_dudvmap, vec2(waterTex2 * tscale)) * 2.0 - 1.0;
vec4 dist = texture2D(water_dudvmap, vec2(waterTex1 + disdis*sca2)) * 2.0 - 1.0;
vec4 fdist = normalize(dist);
fdist *= sca;

//normalmap
vec4 nmap0 = texture2D(water_normalmap, vec2(waterTex1+ disdis*sca2)) * 2.0 - 1.0;
vec4 nmap2 = texture2D(water_normalmap, vec2(waterTex2 * tscale)) * 2.0 - 1.0;
vec4 vNorm = normalize(nmap0 + nmap2);

//load reflection
vec4 tmp = vec4(lightdir, 0.0);
vec4 refTex = texture2D(water_reflection, vec2(tmp));
vec4 refl = normalize(refTex);

vec3 N0 = vec3(texture2D(water_normalmap, vec2(waterTex1+ disdis*sca2)) * 2.0 - 1.0);
vec3 N1 = vec3(texture2D(water_normalmap, vec2(waterTex2 * tscale)) * 2.0 - 1.0);
vec3 N = normalize(normal+N0+N1);

vec3 specular_color = vec3(gl_LightSource[0].diffuse)
		* pow(max(0.0, dot(N, H)), water_shininess) * 6.0;

vec4 specular = vec4(specular_color,0.5);

//calculate fresnel
vec4 invfres = vec4( dot(vNorm, viewt) );
vec4 fres = vec4(1.0) + invfres; 
refl *= fres;

// take rain into account
float rain_factor = 0.7 - RainNorm;
rain_factor = clamp(rain_factor, 0, 1);

if (RainNorm > 0)
{
	refl *= (0.9, 1.0, 0.6 * rain_factor, 1.0);
}
else
{
	refl *= (0.9, 1.0, 0.6, 1.0);
}

specular = specular *  0.4 * rain_factor;

vec4 finalColor = refl + specular;

float fogFactor;
float fogCoord = ecPosition.z;
const float LOG2 = 1.442695;
fogFactor = exp2(-gl_Fog.density * gl_Fog.density * fogCoord * fogCoord * LOG2);

vec4 ambient_light = gl_LightSource[0].diffuse;

	finalColor *= ambient_light;

	if(gl_Fog.density == 1.0)
		fogFactor=1.0;

gl_FragColor = mix(gl_Fog.color,finalColor, fogFactor);

}