#pragma kernel CSMain
#define NUM_THREADS 8

RWStructuredBuffer<float4> KinectGridBuffer;
RWStructuredBuffer<float3> VelocityBuffer;
RWStructuredBuffer<float> TemperatureBuffer;
RWStructuredBuffer<float> ObstacleBuffer;
RWStructuredBuffer<float> DensityBuffer;

float4 FluidDim;
float timeStep;
float temperatureAmount;
float densityAmount;
float kinectAmount;

[numthreads(NUM_THREADS, NUM_THREADS, NUM_THREADS)]
void CSMain(uint3 id : SV_DispatchThreadID)
{
	int idx = id.x + id.y*FluidDim.x + id.z*FluidDim.x*FluidDim.y;

	float4 value = KinectGridBuffer[idx];
	float3 vel = lerp(value.xyz, float3(0, 0, 0), 0.05f);
	float obs = lerp(value.w, 0, 0.2f);

	KinectGridBuffer[idx] = float4(vel, obs);
	//KinectGridBuffer[idx] = float4(1, 0, 0, 1);

	float obstacle = 0;
	
	// boundary
	{
		if ((int)id.x - 1 < 0) obstacle = 1;
		if ((int)id.x + 1 > (int)FluidDim.x - 1) obstacle = 1;

		if ((int)id.y - 1 < 0) obstacle = 1;
		if ((int)id.y + 1 > (int)FluidDim.y - 1) obstacle = 1;

		if ((int)id.z - 1 < 0) obstacle = 1;
		if ((int)id.z + 1 > (int)FluidDim.z - 1) obstacle = 1;
	}
	
	//
	obstacle = max(obstacle, KinectGridBuffer[idx].w);
	obstacle = saturate(obstacle);

	//ObstacleBuffer[idx] = obstacle;
	float3 velocity = VelocityBuffer[idx];

	float density = DensityBuffer[idx];
	//if (id.y == 1) density += 10.0f * timeStep;
	density += KinectGridBuffer[idx].w * kinectAmount * densityAmount * timeStep * length(velocity);
	density = max(density, 0);
	//DensityBuffer[idx] = density;
	
	float temperature = TemperatureBuffer[idx];
	temperature += KinectGridBuffer[idx].w * kinectAmount * temperatureAmount * timeStep * length(velocity);
	temperature = max(temperature, 0);
	TemperatureBuffer[idx] = temperature;

	velocity += KinectGridBuffer[idx].xyz * kinectAmount * 10.0;
	VelocityBuffer[idx] = velocity;
}