// MinecraftPT — WaterRefraction_FS
// Water refraction pass: sample the solid scene with wave-based offset.

#include "/Lib/Settings.glsl"
#include "/Lib/Utilities.glsl"
#include "/Lib/GbufferData.glsl"
#include "/Lib/IndividualFunctions/WaterWaves.glsl"

uniform sampler2D colortex12; // solid scene
uniform sampler2D colortex4;  // translucent albedo

layout(location = 0) out vec4 colorOut;

void main(){
	ivec2 texelCoord = ivec2(gl_FragCoord.xy);

	float depth = texelFetch(depthtex0, texelCoord, 0).r;
	if (depth >= 1.0){
		colorOut = texelFetch(colortex12, texelCoord, 0);
		return;
	}

	vec4 gbuffer5 = texelFetch(colortex5, texelCoord, 0);
	float matID = gbuffer5.a * 255.0;

	if (matID != MATID_WATER){
		colorOut = texelFetch(colortex12, texelCoord, 0);
		return;
	}

	// Reconstruct world position
	vec4 viewPos = gbufferProjectionInverse * vec4(vec2(texelCoord) / screenSize * 2.0 - 1.0, depth * 2.0 - 1.0, 1.0);
	viewPos.xyz /= viewPos.w;
	vec3 worldPos = gbufferModelViewInverse[3].xyz + viewPos.xyz;

	// Wave normal-based refraction offset
	vec3 waveNormal = GetWaveNormal(worldPos, 0.5);
	vec3 viewDir = normalize(-viewPos.xyz);
	vec3 refracted = refract(viewDir, waveNormal, 0.75);

	// Sample the solid scene with the refraction offset
	vec3 refractedDir = mat3(gbufferModelView) * refracted;
	vec2 refractedCoord = viewPos.xy / viewPos.z * refractedDir.xy / refractedDir.z * 0.5 + 0.5;
	vec2 sampleCoord = refractedCoord * screenSize;

	vec3 color = textureLod(colortex12, sampleCoord / screenSize, 0.0).rgb;

	// Water depth color fade
	vec3 waterColor = texelFetch(colortex4, texelCoord, 0).rgb;
	color = mix(color, waterColor, 0.3);

	colorOut = vec4(color, 1.0);
}