#if !(defined(VFX_VARYING_PS_INPUTS) && defined(VFX_VARYING_POSCS))
#error VFX_VARYING_PS_INPUTS and VFX_VARYING_POSCS must be defined.
#endif

${VFXPerPassInclude}
${VFXGeneratedBlockFunction}

struct vs_input
{
	VFX_DECLARE_INSTANCE_ID
};

#pragma vertex vert
float4 ClipOnNearPlane(float4 pos, float4 other)
{
	if (pos.w >= _ProjectionParams.y || other.w < _ProjectionParams.y)
		return pos;

	// Project on near plane
	float ratio = (_ProjectionParams.y - pos.w) / (other.w - pos.w);
	return pos + (other - pos) * ratio;
}

VFX_VARYING_PS_INPUTS vert(uint id : SV_VertexID, vs_input i)
{
	VFX_VARYING_PS_INPUTS o = (VFX_VARYING_PS_INPUTS)0;

	UNITY_SETUP_INSTANCE_ID(i);
	UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);

	uint index = (id >> 2) + VFX_GET_INSTANCE_ID(i) * 2048;

	${VFXInitInstancing}
	${VFXLoadGraphValues}

	${VFXLoadContextData}
	uint systemSeed = contextData.systemSeed;
	uint nbMax = contextData.maxParticleCount;

	${VFXLoadAttributesOrCull}
	${VFXProcessBlocks}

	if (!attributes.alive)
		return o;

	#if TARGET_FROM_ATTRIBUTES
	${VFXLoadSize}
	float4x4 elementToVFX = GetElementToVFXMatrix(
		attributes.axisX,
		attributes.axisY,
		attributes.axisZ,
		float3(attributes.angleX,attributes.angleY,attributes.angleZ),
		float3(attributes.pivotX,attributes.pivotY,attributes.pivotZ),
		size3,
		attributes.position);

	attributes.position = mul(elementToVFX,float4(0,0,0,1)).xyz;

	${VFXLoadParameter:{targetOffset}}
	attributes.targetPosition = mul(elementToVFX,float4(targetOffset,1)).xyz;
	#endif

	float4 pos0 = TransformPositionVFXToClip(attributes.position);
	float4 pos1 = TransformPositionVFXToClip(attributes.targetPosition);

	pos0 = ClipOnNearPlane(pos0, pos1);
	pos1 = ClipOnNearPlane(pos1, pos0);

	float2 ndcPos0 = pos0.xy / pos0.w;
	float2 ndcPos1 = pos1.xy / pos1.w;

	float2 dir = ndcPos0 - ndcPos1;
	float2 normal = normalize(dir.yx * float2(-1,abs(UNITY_MATRIX_P[1][1]) / UNITY_MATRIX_P[0][0]));

#if IS_OPAQUE_PARTICLE
	const float thicknessMul = 1.0f; // pixel perfect
#else
	const float thicknessMul = 2.0f; // for AA
#endif
	normal *= thicknessMul / _ScreenParams.xy;

	float4 dPos0 = float4(normal * pos0.w, 0.0f, 0.0f);
	float4 dPos1 = float4(normal * pos1.w, 0.0f, 0.0f);
	float4 vPosArray[4] = { pos0 + dPos0, pos0 - dPos0, pos1 + dPos1, pos1 - dPos1};

	#ifdef VFX_VARYING_PIXELOFFSET
	o.VFX_VARYING_PIXELOFFSET = (id & 1) ? -1.0f : 1.0f;
	#endif

	// If ever used we need the position in vfx space (we dont take into account the pixel offset)
	float3 vPos = ((id >> 1) & 1) ? attributes.targetPosition : attributes.position;

	o.VFX_VARYING_POSCS = vPosArray[id & 3];

	${VFXVertexComputeCurrentAndPreviousClipPos}
	${VFXVertexCommonProcess}
	${VFXVertexAdditionalProcess}

	return o;
}