#version 450

#include "compiled.inc"
#include "std/gbuffer.glsl"
#include "std/math.glsl"

uniform sampler2D gbufferD;
uniform sampler2D tex;
uniform sampler2D sbase;
uniform sampler2D sdetail;
uniform sampler2D sfoam;

#ifdef _SSR
uniform mat4 P;
uniform mat3 V3;
#ifdef _CPostprocess
uniform vec3 PPComp9;
uniform vec3 PPComp10;
#endif
#endif

#ifdef _Rad
uniform sampler2D senvmapRadiance;
#endif

uniform float time;
uniform vec3 eye;
uniform vec3 eyeLook;
uniform vec2 cameraProj;
uniform vec3 ld;
uniform float envmapStrength;

in vec2 texCoord;
in vec3 viewRay;
out vec4 fragColor;

#ifdef _SSR
vec3 hitCoord;
float depth;

const int numBinarySearchSteps = 7;
const int maxSteps = int(ceil(1.0 / ssrRayStep) * ssrSearchDist);

vec2 getProjectedCoord(const vec3 hit) {
	vec4 projectedCoord = P * vec4(hit, 1.0);
	projectedCoord.xy /= projectedCoord.w;
	projectedCoord.xy = projectedCoord.xy * 0.5 + 0.5;
	#ifdef _InvY
	projectedCoord.y = 1.0 - projectedCoord.y;
	#endif
	return projectedCoord.xy;
}

float getDeltaDepth(const vec3 hit) {
	depth = textureLod(gbufferD, getProjectedCoord(hit), 0.0).r * 2.0 - 1.0;
	vec3 viewPos = getPosView(viewRay, depth, cameraProj);
	return viewPos.z - hit.z;
}

vec4 binarySearch(vec3 dir) {
	float ddepth;
	for (int i = 0; i < numBinarySearchSteps; i++) {
		dir *= 0.5;
		hitCoord -= dir;
		ddepth = getDeltaDepth(hitCoord);
		if (ddepth < 0.0) hitCoord += dir;
	}
	// Ugly discard of hits too far away
	#ifdef _CPostprocess
		if (abs(ddepth) > PPComp9.z / 500) return vec4(0.0);
	#else
		if (abs(ddepth) > ssrSearchDist / 500) return vec4(0.0);
	#endif
	return vec4(getProjectedCoord(hitCoord), 0.0, 1.0);
}

vec4 rayCast(vec3 dir) {
	#ifdef _CPostprocess
		dir *= PPComp9.x;
	#else
		dir *= ssrRayStep;
	#endif
	for (int i = 0; i < maxSteps; i++) {
		hitCoord += dir;
		if (getDeltaDepth(hitCoord) > 0.0) return binarySearch(dir);
	}
	return vec4(0.0);
}
#endif //SSR

vec3 sampleWaterNormals(vec2 hitXY, float speed, out vec2 tcnor0, out vec2 tcnor1) {
	tcnor0 = hitXY / 3.0;
	vec3 n0 = textureLod(sdetail, tcnor0 + vec2(speed / 60.0, speed / 120.0), 0.0).rgb;
	tcnor1 = hitXY / 6.0 + n0.xy / 20.0;
	vec3 n1 = textureLod(sbase, tcnor1 + vec2(speed / 40.0, speed / 80.0), 0.0).rgb;
	return normalize(n0 + n1 - 1.0);
}

void main() {
	float gdepth = textureLod(gbufferD, texCoord, 0.0).r * 2.0 - 1.0;
	vec3 vray = normalize(viewRay);
	float speed = time * 2.0 * waterSpeed;
	bool isSky = (gdepth == 1.0);

	// Ray-plane intersection with water surface (z = waterLevel)
	float denom = dot(vray, vec3(0.0, 0.0, 1.0));
	float tWater = (waterLevel - eye.z) / denom;
	bool hasWaterHit = (abs(denom) > 0.0001) && (tWater > 0.0);

	if (eye.z < waterLevel) {
		vec2 tc = texCoord;
		float fogFactor;

		if (hasWaterHit && denom > 0.0) {
			// Looking up at water surface - apply normal distortion
			vec3 hit = eye + tWater * vray;
			vec2 tc0, tc1;
			vec3 n2 = sampleWaterNormals(hit.xy * waterFreq, speed, tc0, tc1);
			tc = texCoord + (n2.xy * n2.z) / 30.0 * waterRefract;
			fogFactor = clamp(tWater * waterDensity, 0.0, 0.95);
		} else {
			// Looking forward/down - distort via water surface above fragment
			vec3 p = getPos(eye, eyeLook, vray, gdepth, cameraProj);
			vec2 wxy = isSky ? (eye.xy + vray.xy * 50.0) : p.xy;
			vec2 tc0, tc1;
			vec3 n2 = sampleWaterNormals(wxy * waterFreq, speed, tc0, tc1);
			tc = texCoord + (n2.xy * n2.z) / 30.0 * waterRefract;
			float waterDist = isSky ? 50.0 : length(p - eye);
			fogFactor = clamp(waterDist * waterDensity, 0.0, 0.95);
		}

		vec3 refracted = textureLod(tex, tc, 0.0).rgb;
		fragColor.rgb = mix(refracted, waterColor, fogFactor);
		fragColor.a = 1.0;
		return;
	}

	// Above water
	if (!hasWaterHit || denom >= 0.0) {
		fragColor = vec4(0.0);
		return;
	}

	if (isSky) tWater = min(tWater, 100.0); // Clamp to prevent aliasing at horizon
	vec3 p = isSky ? (eye + tWater * vray) : getPos(eye, eyeLook, vray, gdepth, cameraProj);

	float horizonFactor = clamp(1.0 - tWater / 60.0, 0.0, 1.0);
	if (!isSky && p.z > waterLevel) {
		fragColor = vec4(0.0);
		return;
	}

	// Displace surface
	p.z += (sin(p.x * 10.0 / waterDisplace + speed) * cos(p.y * 10.0 / waterDisplace + speed)
	      + sin(p.x * 20.0 / waterDisplace + speed * 1.3) * cos(p.y * 20.0 / waterDisplace + speed * 1.3) * 0.5)
	      / 50.0 * waterDisplace;

	// Hit plane to determine uvs
	vec3 v = normalize(eye - p);
	float t = (waterLevel - eye.z) / dot(v, vec3(0.0, 0.0, 1.0));
	vec3 hit = eye + t * v;

	// Sample normal maps
	vec2 tcnor0, tcnor1;
	vec3 n2 = sampleWaterNormals(hit.xy * waterFreq, speed, tcnor0, tcnor1);

	// Refraction
	vec2 tc;
	if (isSky) {
		tc = texCoord + (n2.xy * n2.z) / 30.0 * waterRefract;
	} else {
		float ddepth = textureLod(gbufferD, texCoord + (n2.xy * n2.z) / 40.0, 0.0).r * 2.0 - 1.0;
		vec3 p2 = getPos(eye, eyeLook, vray, ddepth, cameraProj);
		tc = p2.z > waterLevel ? texCoord : texCoord + (n2.xy * n2.z) / 30.0 * waterRefract;
	}

	// Light
	float fresnel = 1.0 - max(dot(n2, v), 0.0);
	fresnel = 0.02 + 0.98 * pow(fresnel, 5.0);
	vec3 r = reflect(-v, n2);
	#ifdef _Rad
	vec3 reflectedEnv = textureLod(senvmapRadiance, envMapEquirect(r), 0).rgb;
	#else
	const vec3 reflectedEnv = vec3(0.5);
	#endif
	vec3 refracted = textureLod(tex, tc, 0.0).rgb;

	#ifdef _SSR
	float roughness = 0.1;//unpackFloat(g0.b).y;
	//if (roughness == 1.0) { fragColor.rgb = vec3(0.0); return; }

	float spec = 0.9;//fract(textureLod(gbuffer1, texCoord, 0.0).a);
	//if (spec == 0.0) { fragColor.rgb = vec3(0.0); return; }

	vec3 viewNormal = V3 * n2;
	vec3 viewPos = isSky ? vec3(0.0) : getPosView(viewRay, gdepth, cameraProj);
	vec3 reflected = reflect(normalize(viewPos), viewNormal);
	hitCoord = viewPos;

	#ifdef _CPostprocess
		vec3 dir = reflected * (1.0 - rand(texCoord) * PPComp10.y * roughness) * 2.0;
	#else
		vec3 dir = reflected * (1.0 - rand(texCoord) * ssrJitter * roughness) * 2.0;
	#endif

	vec4 coords = rayCast(dir);

	vec2 deltaCoords = abs(vec2(0.5, 0.5) - coords.xy);
	float screenEdgeFactor = clamp(1.0 - (deltaCoords.x + deltaCoords.y), 0.0, 1.0);

	float reflectivity = 1.0 - roughness;
	#ifdef _CPostprocess
	float intensity = pow(reflectivity, PPComp10.x) * screenEdgeFactor * clamp(-reflected.z, 0.0, 1.0) * clamp((PPComp9.z - length(viewPos - hitCoord)) * (1.0 / PPComp9.z), 0.0, 1.0) * coords.w;
	#else
	float intensity = pow(reflectivity, ssrFalloffExp)*screenEdgeFactor*clamp(-reflected.z, 0.0, 1.0)*clamp((ssrSearchDist - length(viewPos - hitCoord))*(1.0 / ssrSearchDist), 0.0, 1.0)*coords.w;
	#endif
	intensity = clamp(intensity, 0.0, 1.0);
	vec3 reflCol = textureLod(tex, coords.xy, 0.0).rgb;
	fragColor.rgb = mix(refracted, reflCol * intensity * 0.5, waterReflect * fresnel * 0.5);
	fragColor.rgb = mix(fragColor.rgb, reflectedEnv, waterReflect * fresnel);
	#else
	fragColor.rgb = mix(refracted, reflectedEnv, waterReflect * fresnel);
	#endif
	// Water color tint - blend rather than multiply to preserve brightness
	float colorMix = isSky ? 0.7 : 0.5;
	fragColor.rgb = mix(fragColor.rgb, fragColor.rgb * waterColor, colorMix * horizonFactor);
	// Blinn-Phong specular using half-vector, faded at horizon
	vec3 h = normalize(v + ld);
	float specAmount = pow(max(dot(n2, h), 0.0), 200.0) * (200.0 + 8.0) / (PI * 8.0);
	fragColor.rgb += specAmount * (isSky ? 0.3 : 1.0) * horizonFactor;
	// Depth fog - blend toward waterColor with depth, faded at horizon
	float depthFog = clamp(-(p.z - waterLevel) * waterDensity, 0.0, 0.9);
	fragColor.rgb = mix(fragColor.rgb, waterColor, depthFog * horizonFactor);
	// Alpha fades smoothly at horizon instead of hard cut
	fragColor.a = isSky ? horizonFactor : clamp(abs(p.z - waterLevel) * 5.0, 0.0, 1.0);

	// Foam - based on actual geometry depth below water surface
	float fd = isSky ? 1.0 : abs(p.z - waterLevel);
	if (fd < 0.1) {
		// Based on foam by Owen Deery
		// http://fire-face.com/personal/water
		// Distance-based LOD blurs foam at range to reduce noise
		float foamLod = clamp(tWater / 15.0, 0.0, 5.0);
		vec2 foamUV0 = tcnor0 * 3.0 + vec2(speed / 30.0, speed / 50.0);
		vec2 foamUV1 = tcnor1 * 4.0 + vec2(-speed / 35.0, speed / 45.0);
		vec3 foamMask0 = textureLod(sfoam, foamUV0, foamLod).rgb;
		vec3 foamMask1 = textureLod(sfoam, foamUV1, foamLod).rgb;
		float foamStrength = clamp(1.0 - foamMask0.r * 0.5 - foamMask1.b * 0.5, 0.0, 1.0);
		float fac = (1.0 - (fd * (1.0 / 0.1))) * horizonFactor;
		fragColor.rgb = mix(fragColor.rgb, mix(fragColor.rgb, waterColor + 0.2, foamStrength), clamp(fac, 0.0, 1.0) * 0.5);
	}
}