// MinecraftPT — SpecularTracing_FS
// Specular reflection path tracing at half resolution.
// Output: colortex9 = noisy specular, colortex11 = history (ping-pong)

#include "/Lib/Settings.glsl"
#include "/Lib/Utilities.glsl"
#include "/Lib/BasicFunctions/LightingConstants.glsl"
#include "/Lib/GbufferData.glsl"
#include "/Lib/PathTracing/Tracer/TracingNoise.glsl"
#include "/Lib/PathTracing/Tracer/TracingUtilities.glsl"
#include "/Lib/PathTracing/Tracer/SpecularTracer.glsl"
#include "/Lib/BasicFunctions/TemporalNoise.glsl"

layout(location = 0) out vec4 specularOut;

void main(){
	ivec2 texelCoord = ivec2(gl_FragCoord.xy);
	ivec2 fullCoord = texelCoord * 2;

	float depth = texelFetch(depthtex0, fullCoord, 0).r;
	if (depth >= 1.0){
		specularOut = vec4(0.0);
		return;
	}

	vec4 normalData = texelFetch(colortex1, fullCoord, 0);
	vec3 worldNormal = DecodeNormal(normalData.xy);
	vec4 materialData = texelFetch(colortex2, fullCoord, 0);

	float roughness = 1.0 - materialData.r;
	roughness = roughness * roughness;
	float metalness = materialData.g;

	// Skip rough non-metal surfaces when rough specular is disabled
	#if ENABLE_ROUGH_SPECULAR == 0
		if (roughness > 0.5 && metalness < 0.04){
			specularOut = vec4(0.0);
			return;
		}
	#endif

	// Reconstruct view position
	vec4 viewPos = gbufferProjectionInverse * vec4(vec2(fullCoord) / screenSize * 2.0 - 1.0, depth * 2.0 - 1.0, 1.0);
	viewPos.xyz /= viewPos.w;

	vec3 worldPos = gbufferModelViewInverse[3].xyz + viewPos.xyz;
	vec3 viewDir = normalize(-viewPos.xyz);

	vec2 noise = GetTracingNoise2(vec2(texelCoord), frameCounter, 1);

	// Importance-sample GGX reflection direction
	vec3 reflDir = ImportanceSampleGGX(noise, worldNormal, roughness);

	// Or use pure reflection for smooth surfaces
	if (roughness < 0.05){
		reflDir = reflect(-viewDir, worldNormal);
	}

	// Trace the specular ray
	vec3 result = SpecularTrace(WorldToVoxel(worldPos + worldNormal * 0.02), reflDir, PT_SPECULAR_TRACING_DISTANCE, noise);

	specularOut = vec4(result, 1.0);
}