// 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
//  Major update and revisions - 2011-10-07
//  © Emilian Huminiuc and Vivian Meazza
//  Optimisation - 2012-5-05
//  Based on ideas by Thorsten Renk
//  © Emilian Huminiuc and Vivian Meazza

#version 120

uniform sampler2D water_normalmap;
uniform sampler2D water_reflection;
uniform sampler2D water_dudvmap;
uniform sampler2D water_reflection_grey;
uniform sampler2D sea_foam;
uniform sampler2D perlin_normalmap;

uniform sampler3D Noise;

uniform float saturation, Overcast, WindE, WindN;
uniform float CloudCover0, CloudCover1, CloudCover2, CloudCover3, CloudCover4;
uniform float osg_SimulationTime;
uniform int Status;

varying vec4 waterTex1; //moving texcoords
varying vec4 waterTex2; //moving texcoords

varying vec3 viewerdir;
varying vec3 lightdir;
varying vec3 normal;

uniform    float WaveFreq ;
uniform    float WaveAmp ;
uniform    float WaveSharp ;
uniform    float WaveAngle ;
uniform    float WaveFactor ;
uniform    float WaveDAngle ;
uniform    float normalmap_dds;

////fog "include" /////
uniform int fogType;

vec3 fog_Func(vec3 color, int type);
//////////////////////

const vec4 AllOnes = vec4(1.0);

/////// functions /////////

void rotationmatrix(in float angle, out mat4 rotmat)
	{
	rotmat = mat4( cos( angle ), -sin( angle ), 0.0, 0.0,
		sin( angle ),  cos( angle ), 0.0, 0.0,
		0.0         ,  0.0         , 1.0, 0.0,
		0.0         ,  0.0         , 0.0, 1.0 );
	}

// wave functions ///////////////////////

struct Wave {
	float freq;  // 2*PI / wavelength
	float amp;   // amplitude
	float phase; // speed * 2*PI / wavelength
	vec2 dir;
	};

Wave wave0 = Wave(1.0, 1.0, 0.5, vec2(0.97, 0.25));
Wave wave1 = Wave(2.0, 0.5, 1.3, vec2(0.97, -0.25));
Wave wave2 = Wave(1.0, 1.0, 0.6, vec2(0.95, -0.3));
Wave wave3 = Wave(2.0, 0.5, 1.4, vec2(0.99, 0.1));

float evaluateWave(in Wave w, vec2 pos, float t)
	{
	return w.amp * sin( dot(w.dir, pos) * w.freq + t * w.phase);
	}

// derivative of wave function
float evaluateWaveDeriv(Wave w, vec2 pos, float t)
	{
	return w.freq * w.amp * cos( dot(w.dir, pos)*w.freq + t*w.phase);
	}

// sharp wave functions
float evaluateWaveSharp(Wave w, vec2 pos, float t, float k)
	{
	return w.amp * pow(sin( dot(w.dir, pos)*w.freq + t*w.phase)* 0.5 + 0.5 , k);
	}

float evaluateWaveDerivSharp(Wave w, vec2 pos, float t, float k)
	{
	return k*w.freq*w.amp * pow(sin( dot(w.dir, pos)*w.freq + t*w.phase)* 0.5 + 0.5 , k - 1.0) * cos( dot(w.dir, pos)*w.freq + t*w.phase);
	}

void sumWaves(float angle, float dangle, float windScale, float factor, out float ddx, float ddy)
	{
	mat4 RotationMatrix;
	float deriv;
	vec4 P = waterTex1 * 1024.0;

	rotationmatrix(radians(angle + dangle * windScale + 0.6 * sin(P.x * factor)), RotationMatrix);
	P *= RotationMatrix;

	P.y += evaluateWave(wave0, P.xz, osg_SimulationTime);
	deriv = evaluateWaveDeriv(wave0, P.xz, osg_SimulationTime );
	ddx = deriv * wave0.dir.x;
	ddy = deriv * wave0.dir.y;

	P.y += evaluateWave(wave1, P.xz, osg_SimulationTime);
	deriv = evaluateWaveDeriv(wave1, P.xz, osg_SimulationTime);
	ddx += deriv * wave1.dir.x;
	ddy += deriv * wave1.dir.y;

	P.y += evaluateWaveSharp(wave2, P.xz, osg_SimulationTime, WaveSharp);
	deriv = evaluateWaveDerivSharp(wave2, P.xz, osg_SimulationTime, WaveSharp);
	ddx += deriv * wave2.dir.x;
	ddy += deriv * wave2.dir.y;

	P.y += evaluateWaveSharp(wave3, P.xz, osg_SimulationTime, WaveSharp);
	deriv = evaluateWaveDerivSharp(wave3, P.xz, osg_SimulationTime, WaveSharp);
	ddx += deriv * wave3.dir.x;
	ddy += deriv * wave3.dir.y;
	}

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);

	mat4 RotationMatrix;

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

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

	// half vector
	vec3 H = normalize(L + E);

	vec3 Normal = normalize(normal);

	const float water_shininess = 240.0;

	float range = gl_ProjectionMatrix[3].z/(gl_FragCoord.z * -2.0 + 1.0 - gl_ProjectionMatrix[2].z);

	// approximate cloud cover
	float cover = 0.0;
	//bool Status = true;

	float windEffect = sqrt( WindE*WindE + WindN*WindN ) * 0.6; 	        //wind speed in kt
	float windScale =  15.0/(3.0 + windEffect);             				//wave scale
	float windEffect_low = 0.3 + 0.7 * smoothstep(0.0, 5.0, windEffect); 	//low windspeed wave filter
	float waveRoughness = 0.01 + smoothstep(0.0, 40.0, windEffect);			//wave roughness filter

	float mixFactor = 0.2 + 0.02 * smoothstep(0.0, 50.0, windEffect);
	//mixFactor = 0.2;
	mixFactor = clamp(mixFactor, 0.3, 0.8);

	// sine waves

	// Test data
	//float WaveFreq =1.0;
	//float WaveAmp = 1000.0;
	//float WaveSharp = 10.0;

	  vec4 ddxVec = vec4(0.0);
	  vec4 ddyVec = vec4(0.0);
	  int detailFlag = 0;

	//uncomment to test
	//range = -20000;

	if (range > -15000.0 || dot(Normal,H) > 0.95 ) {

		float ddx = 0.0, ddy = 0.0;
		float ddx1 = 0.0, ddy1 = 0.0;
		float ddx2 = 0.0, ddy2 = 0.0;
		float ddx3 = 0.0, ddy3 = 0.0;
		float waveamp;

		float angle = 0.0;

		wave0.freq = WaveFreq ;
		wave0.amp = WaveAmp;
		wave0.dir =  vec2(cos(radians(angle)), sin(radians(angle)));

		angle -= 45.0;
		wave1.freq = WaveFreq * 2.0 ;
		wave1.amp = WaveAmp * 1.25;
		wave1.dir =  vec2(cos(radians(angle)), sin(radians(angle)));

		angle += 30.0;
		wave2.freq = WaveFreq * 3.5;
		wave2.amp = WaveAmp * 0.75;
		wave2.dir =  vec2(cos(radians(angle)), sin(radians(angle)));

		angle -= 50.0;
		wave3.freq = WaveFreq * 3.0 ;
		wave3.amp = WaveAmp * 0.75;
		wave3.dir =  vec2(cos(radians(angle)), sin(radians(angle)));

		// sum waves

		ddx = 0.0, ddy = 0.0;
		sumWaves(WaveAngle, -1.5, windScale, WaveFactor, ddx, ddy);

		ddx1 = 0.0, ddy1 = 0.0;
		sumWaves(WaveAngle, 1.5, windScale, WaveFactor, ddx1, ddy1);

		//reset the waves
		angle = 0.0;
		waveamp = WaveAmp * 0.75;

		wave0.freq = WaveFreq ;
		wave0.amp = waveamp;
		wave0.dir =  vec2(cos(radians(angle)), sin(radians(angle)));

		angle -= 20.0;
		wave1.freq = WaveFreq * 2.0 ;
		wave1.amp = waveamp * 1.25;
		wave1.dir =  vec2(cos(radians(angle)), sin(radians(angle)));

		angle += 35.0;
		wave2.freq = WaveFreq * 3.5;
		wave2.amp = waveamp * 0.75;
		wave2.dir =  vec2(cos(radians(angle)), sin(radians(angle)));

		angle -= 45.0;
		wave3.freq = WaveFreq * 3.0 ;
		wave3.amp = waveamp * 0.75;
		wave3.dir =  vec2(cos(radians(angle)), sin(radians(angle)));

		// sum waves
		ddx2 = 0.0, ddy2 = 0.0;
		sumWaves(WaveAngle + WaveDAngle, -1.5, windScale, WaveFactor, ddx2, ddy2);

		ddx3 = 0.0, ddy3 = 0.0;
		sumWaves(WaveAngle + WaveDAngle, 1.5, windScale, WaveFactor, ddx3, ddy3);

		ddxVec = vec4(ddx, ddx1, ddx2, ddx3);
		ddyVec = vec4(ddy, ddy1, ddy2, ddy3);

		//toggle detailFlag
		detailFlag = 1;
		}	// end sine stuff

	float ddxSum = dot(ddxVec, AllOnes);
	float ddySum = dot(ddyVec, AllOnes);

	if (Status == 1){
		cover = min(min(min(min(CloudCover0, CloudCover1),CloudCover2),CloudCover3),CloudCover4);
		} else {
			// hack to allow for Overcast not to be set by Local Weather
			if (Overcast == 0){
				cover = 5;
				} else {
					cover = Overcast * 5;
				}
		}

//	vec4 viewt = normalize(waterTex4);
	vec4 viewt = vec4(-E, 0.0) * 0.6;

	vec4 disdis = texture2D(water_dudvmap, vec2(waterTex2 * tscale)* windScale) * 2.0 - 1.0;

	//normalmaps
	vec4 nmap   = texture2D(water_normalmap, vec2(waterTex1 + disdis * sca2) * windScale) * 2.0 - 1.0;
	vec4 nmap1  = texture2D(perlin_normalmap, vec2(waterTex1 + disdis * sca2) * windScale) * 2.0 - 1.0;

	rotationmatrix(radians(3.0 * sin(osg_SimulationTime * 0.0075)), RotationMatrix);
	nmap  += texture2D(water_normalmap, vec2(waterTex2 * RotationMatrix * tscale) * windScale) * 2.0 - 1.0;
	nmap1 += texture2D(perlin_normalmap, vec2(waterTex2 * RotationMatrix * tscale) * windScale) * 2.0 - 1.0;

	nmap  *= windEffect_low;
	nmap1 *= windEffect_low;

	// mix water and noise, modulated by factor
	vec4 vNorm = normalize(mix(nmap, nmap1, mixFactor) * waveRoughness);
	vNorm.r += ddxSum;

    if (normalmap_dds > 0)
        vNorm = -vNorm;		//dds fix

	//load reflection
	vec4 tmp = vec4(lightdir, 0.0);
	vec4 refTex = texture2D(water_reflection, vec2(tmp + waterTex1) * 32.0) ;
	vec4 refTexGrey = texture2D(water_reflection_grey, vec2(tmp + waterTex1) * 32.0) ;
	vec4 refl ;

	// Test data
	// cover = 0;

	if(cover >= 1.5){
		refl = normalize(refTex);
		refl.a = 1.0;
		}
	else
		{
		refl = normalize(refTexGrey);
		refl.r *= (0.75 + 0.15 * cover);
		refl.g *= (0.80 + 0.15 * cover);
		refl.b *= (0.875 + 0.125 * cover);
		refl.a  = 1.0;
		}

	vec3 N0 = vec3(texture2D(water_normalmap, vec2(waterTex1 + disdis * sca2) * windScale) * 2.0 - 1.0);
	vec3 N1 = vec3(texture2D(perlin_normalmap, vec2(waterTex1 + disdis * sca) * windScale) * 2.0 - 1.0);

	N0 += vec3(texture2D(water_normalmap, vec2(waterTex1 * tscale) * windScale) * 2.0 - 1.0);
	N1 += vec3(texture2D(perlin_normalmap, vec2(waterTex2 * tscale) * windScale) * 2.0 - 1.0);

	rotationmatrix(radians(2.0 * sin(osg_SimulationTime * 0.005)), RotationMatrix);
	N0 += vec3(texture2D(water_normalmap, vec2(waterTex2 * RotationMatrix * (tscale + sca2)) * windScale) * 2.0 - 1.0);
	N1 += vec3(texture2D(perlin_normalmap, vec2(waterTex2 * RotationMatrix * (tscale + sca2)) * windScale) * 2.0 - 1.0);

	rotationmatrix(radians(-4.0 * sin(osg_SimulationTime * 0.003)), RotationMatrix);
	N0 += vec3(texture2D(water_normalmap, vec2(waterTex1 * RotationMatrix + disdis * sca2) * windScale) * 2.0 - 1.0);
	N1 += vec3(texture2D(perlin_normalmap, vec2(waterTex1 * RotationMatrix + disdis * sca) * windScale) * 2.0 - 1.0);

	if(detailFlag > 0)
		{
			N0 *= windEffect_low;
			N1 *= windEffect_low;
			//N0.r += (ddx + ddx1 + ddx2 + ddx3);
			//N0.g += (ddy + ddy1 + ddy2 + ddy3);

			N0.r += ddxSum;
			N0.g += ddySum;

			Normal = normalize(mix(Normal + N0, Normal + N1, mixFactor) * waveRoughness);

            if (normalmap_dds > 0)
                Normal = -Normal; //dds fix
		}


	// specular
	vec3 specular_color = vec3(gl_LightSource[0].diffuse)
						  * pow(max(0.0, dot(Normal, H)), water_shininess) * 6.0;
	vec4 specular = vec4(specular_color, 0.5);

	specular = specular * saturation * 0.3 ;

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

	//calculate final colour
	vec4 ambient_light = gl_LightSource[0].diffuse;
	vec4 finalColor;

	if(cover >= 1.5){
		finalColor = refl + specular;
		} else {
			finalColor = refl;
		}

	//add foam
	vec4 foam_texel = texture2D(sea_foam, vec2(waterTex2 * tscale) * 25.0);
	if (range > -10000.0){

		float foamSlope = 0.1 + 0.1 * windScale;
		//float waveSlope = mix(N0.g, N1.g, 0.25);
		float waveSlope = Normal.g;

		if (windEffect >= 8.0)

			if (waveSlope >= foamSlope){
				finalColor = mix(finalColor, max(finalColor, finalColor + foam_texel),
											  smoothstep(0.01, 0.50, Normal.g));
			}

	} // end range


	finalColor *= ambient_light;

	//gl_FragColor = mix(gl_Fog.color, finalColor, fogFactor);
	finalColor.rgb = fog_Func(finalColor.rgb, fogType);
	gl_FragColor = finalColor;
	}