////This generates a combined clipmap so we don't have to sample every volume map every frame////
//TODO: Add cascades or tapper

#pragma kernel ClipMapGen
#pragma kernel ClipMapClear
#pragma kernel ClipMapHeight

Texture3D<float4>	PreResult;
RWTexture3D<float4> Result;

SamplerState my_point_clamp_sampler;

float3 ClipmapWorldPosition;
float  ClipmapScale;

float3	VolumeWorldSize; 
float3	VolumeWorldPosition;

Texture3D<float4> VolumeMap;
SamplerState trilinear_clamp_sampler;
float VolumeDensity;

shared float _GlobalExtinction;
float4 clearColor;

[numthreads(4, 4, 4)]
void ClipMapClear(uint3 id : SV_DispatchThreadID)
{
	Result[id.xyz] = float4(0, 0, 0, 0);
	//Result[id.xyz] = clearColor;
}

[numthreads(4,4,4)]
void ClipMapGen (uint3 id : SV_DispatchThreadID)
{
	//uint count, stride;

	float3 ClipRes = float3(0,0,0);
	Result.GetDimensions(ClipRes.x, ClipRes.y, ClipRes.z);
	float4 UVW;
	UVW.xyz = (id + 0.5) / ClipRes.xyz; //0-1 scaling
	UVW.w = 1;

	float4 WorldCoord = UVW * ClipmapScale + ClipmapWorldPosition.xyzz;
	float3 MapUVW = (WorldCoord.xyz - VolumeWorldPosition) / VolumeWorldSize;

	//TODO: Make sampling calculations run or not if they are inside or out of the clipped area
	float ClipUVW  =
		step(MapUVW.x, 1) * step(0, MapUVW.x) *
		step(MapUVW.y, 1) * step(0, MapUVW.y) *
		step(MapUVW.z, 1) * step(0, MapUVW.z);

	//float tempden = distance(WorldCoord.xyz,0) > 3 ? 0:10 ;
	float3 VolRes = float3(0, 0, 0);
	VolumeMap.GetDimensions(VolRes.x, VolRes.y, VolRes.z);
	//float3 VolPixSize = VolumeWorldSize / VolRes;
	//float3 ClipPixSize = ClipmapScale / ClipRes;

	// Move this math into the C# side, no reason to do this per pixel!
	float3 VolPixPerClipPix = (ClipmapScale * VolRes) / (VolumeWorldSize * ClipRes); // ClipPixSize / VolPixSize;
	float maxScale = max(VolPixPerClipPix.x, max(VolPixPerClipPix.y, VolPixPerClipPix.z));
	float mip = log2(maxScale);
	
	//Sample baked volume and clip it off to its area
	//Doing max of the two results to account for overlaps

	float4 colors = max(PreResult[id.xyz], VolumeMap.SampleLevel(trilinear_clamp_sampler, MapUVW, mip) * ClipUVW);
	colors.a = 0;
	Result[id.xyz] = colors;
}

[numthreads(4, 4, 4)]
void MediapGen(uint3 id : SV_DispatchThreadID)
{

}

[numthreads(4, 4, 4)]
void ClipMapHeight(uint3 id : SV_DispatchThreadID)
{
	//uint count, stride;

	float4 UVW = float4(0,0,0,0);
	Result.GetDimensions(UVW.x, UVW.y, UVW.z);

	UVW.xyz = (id + 0.5) / UVW.xyz; //0-1 scaling
	UVW.w = 1;

	float4 WorldCoord = UVW * ClipmapScale + ClipmapWorldPosition.xyzz;

	//float heightDens = WorldCoord.y > 0 ? 0:1;

	float heightDens = _GlobalExtinction;

	Result[id.xyz] = max(PreResult[id.xyz].rgba,float4(0,0,0,heightDens));
;
}