// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

Shader "Time of Day/Stars"

{

	Properties

	{

	}

	CGINCLUDE

	#include "UnityCG.cginc"

	#include "TOD_Base.cginc"

	struct v2f {

		float4 position : SV_POSITION;

		half4  color    : COLOR;

		half3  tex      : TEXCOORD0;

	};

	v2f vert(appdata_full v) {

		v2f o;

		float tanFovHalf = 1.0 / max(0.1, UNITY_MATRIX_P[0][0]); // (r-l) / (2*n)

		float radius = 4.0 * tanFovHalf / _ScreenParams.x;

		float alpha = TOD_StarBrightness * TOD_StarVisibility * 0.00001 * v.color.a / (radius * radius);

		float size = TOD_StarSize * radius;

		float3 u_vec = v.tangent;

		float3 v_vec = cross(v.normal, v.tangent);

		float u_fac = v.texcoord.x - 0.5;

		float v_fac = v.texcoord.y - 0.5;

		v.vertex.xyz -= u_vec * u_fac * size;

		v.vertex.xyz -= v_vec * v_fac * size;

		o.position = TOD_TRANSFORM_VERT(v.vertex);

		float3 skyPos = mul(TOD_World2Sky, mul(unity_ObjectToWorld, v.vertex)).xyz;

		o.tex.xy = 2.0 * v.texcoord - 1.0;

		o.tex.z  = skyPos.y * 25;

		o.color = half4(alpha, alpha, alpha, 1);

#if !TOD_OUTPUT_LINEAR

		o.color = TOD_LINEAR2GAMMA(o.color);

#endif

		return o;

	}

	half4 frag(v2f i) : COLOR {

		half  dist  = length(i.tex.xy);

		half  spot  = saturate(1.0 - dist);

		half  alpha = saturate(i.tex.z) * spot;

		return half4(i.color.rgb * alpha, i.color.a);

	}

	ENDCG

	SubShader

	{

		Tags

		{

			"Queue"="Background+20"

			"RenderType"="Background"

			"IgnoreProjector"="True"

		}

		Pass

		{

			ZWrite Off

			ZTest LEqual

			Blend One One

			Fog { Mode Off }

			CGPROGRAM

			#pragma vertex vert

			#pragma fragment frag

			#pragma multi_compile _ TOD_OUTPUT_LINEAR

			ENDCG

		}

	}

	Fallback Off

}