#pragma multi_compile __ VR

float4x4 _PVMMatrix;
float4x4 _Cam2WorldMatrix;

#if VR
float4x4 _PVMMatrix_L;
float4x4 _PVMMatrix_R;
float4x4 _Cam2WorldMatrix_L;
float4x4 _Cam2WorldMatrix_R;
#endif

float4 toWorldPosition(float4 p_in)
{
	return mul(_PVMMatrix, p_in);
}

float toDepth(float4 p_in)
{
#if defined(VR)
	return -toWorldPosition(p_in).z;
#else
	return toWorldPosition(p_in).z;
#endif
}

float3 getRayDirection(float2 uv)
{
#if VR
	if (unity_CameraProjection[0][2] < 0)
	{
		_Cam2WorldMatrix = _Cam2WorldMatrix_L;
		_PVMMatrix = mul(unity_CameraProjection, _PVMMatrix_L);
	}
	else
	{
		_Cam2WorldMatrix = _Cam2WorldMatrix_R;
		_PVMMatrix = mul(unity_CameraProjection, _PVMMatrix_R);
	}
#endif

	float4x4 m = unity_CameraProjection;
	float near = m[2][3] / (m[2][2] - 1);
	float far = m[2][3] / (m[2][2] + 1);

	float bottom = near * (m[1][2] - 1) / m[1][1];
	float top = near * (m[1][2] + 1) / m[1][1];
	float left = near * (m[0][2] - 1) / m[0][0];
	float right = near * (m[0][2] + 1) / m[0][0];

	float x = uv.x * (right - left) + left;
	float y = uv.y * (top - bottom) + bottom;

#if VR
	float z = near;
#else
	float z = -near;
#endif

	float3 rayDirection = float3(x, y, z);
	rayDirection = mul(_Cam2WorldMatrix, float4(rayDirection, 0)).xyz;
	rayDirection = normalize(rayDirection);
	return rayDirection;
}