// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

Shader "Skybox/6 Sided - Arbitrary Rotation" {
	Properties{
		_Tint("Tint Color", Color) = (.5, .5, .5, .5)
		[Gamma] _Exposure("Exposure", Range(0, 8)) = 1.0
		_Rotation("Rotation", Range(0, 360)) = 0
		_RotationAxis("Rotation axis", Vector) = (0, 1, 0)
		[NoScaleOffset] _FrontTex("Front [+Z]   (HDR)", 2D) = "grey" {}
		[NoScaleOffset] _BackTex("Back [-Z]   (HDR)", 2D) = "grey" {}
		[NoScaleOffset] _LeftTex("Left [+X]   (HDR)", 2D) = "grey" {}
		[NoScaleOffset] _RightTex("Right [-X]   (HDR)", 2D) = "grey" {}
		[NoScaleOffset] _UpTex("Up [+Y]   (HDR)", 2D) = "grey" {}
		[NoScaleOffset] _DownTex("Down [-Y]   (HDR)", 2D) = "grey" {}
	}

		SubShader{
			Tags { "Queue" = "Background" "RenderType" = "Background" "PreviewType" = "Skybox" }
			Cull Off ZWrite Off

			CGINCLUDE
			#include "UnityCG.cginc"

			half4 _Tint;
			half _Exposure;
			float _Rotation;
			float3 _RotationAxis;

			float3 RotateAroundYInDegrees(float3 vertex, float degrees)
			{
				float alpha = degrees * UNITY_PI / 180.0;
				float sina, cosa;
				sincos(alpha, sina, cosa);
				float2x2 m = float2x2(cosa, -sina, sina, cosa);
				return float3(mul(m, vertex.xz), vertex.y).xzy;
			}
			float4x4 rotationMatrix(float3 axis, float angle)
			{
				axis = normalize(axis);
				float s = sin(angle);
				float c = cos(angle);
				float oc = 1.0 - c;

				return float4x4(oc * axis.x * axis.x + c,           oc * axis.x * axis.y - axis.z * s,  oc * axis.z * axis.x + axis.y * s,  0.0,
							oc * axis.x * axis.y + axis.z * s,  oc * axis.y * axis.y + c,           oc * axis.y * axis.z - axis.x * s,  0.0,
							oc * axis.z * axis.x - axis.y * s,  oc * axis.y * axis.z + axis.x * s,  oc * axis.z * axis.z + c,           0.0,
							0.0,                                0.0,                                0.0,                                1.0);
			}

			struct appdata_t {
				float4 vertex : POSITION;
				float2 texcoord : TEXCOORD0;
				UNITY_VERTEX_INPUT_INSTANCE_ID
			};
			struct v2f {
				float4 vertex : SV_POSITION;
				float2 texcoord : TEXCOORD0;
				UNITY_VERTEX_OUTPUT_STEREO
			};
			v2f vert(appdata_t v)
			{
				v2f o;
				UNITY_SETUP_INSTANCE_ID(v);
				UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
				//float3 rotated = RotateAroundYInDegrees(v.vertex, _Rotation);
				float3 rotated = mul(rotationMatrix(normalize(_RotationAxis.xyz), _Rotation * UNITY_PI / 180.0), v.vertex).xyz;
				o.vertex = UnityObjectToClipPos(rotated);
				o.texcoord = v.texcoord;
				return o;
			}
			half4 skybox_frag(v2f i, sampler2D smp, half4 smpDecode)
			{
				half4 tex = tex2D(smp, i.texcoord);
				half3 c = DecodeHDR(tex, smpDecode);
				c = c * _Tint.rgb * unity_ColorSpaceDouble.rgb;
				c *= _Exposure;
				return half4(c, 1);
			}
			ENDCG

			Pass {
				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma target 2.0
				sampler2D _FrontTex;
				half4 _FrontTex_HDR;
				half4 frag(v2f i) : SV_Target { return skybox_frag(i,_FrontTex, _FrontTex_HDR); }
				ENDCG
			}
			Pass{
				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma target 2.0
				sampler2D _BackTex;
				half4 _BackTex_HDR;
				half4 frag(v2f i) : SV_Target { return skybox_frag(i,_BackTex, _BackTex_HDR); }
				ENDCG
			}
			Pass{
				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma target 2.0
				sampler2D _LeftTex;
				half4 _LeftTex_HDR;
				half4 frag(v2f i) : SV_Target { return skybox_frag(i,_LeftTex, _LeftTex_HDR); }
				ENDCG
			}
			Pass{
				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma target 2.0
				sampler2D _RightTex;
				half4 _RightTex_HDR;
				half4 frag(v2f i) : SV_Target { return skybox_frag(i,_RightTex, _RightTex_HDR); }
				ENDCG
			}
			Pass{
				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma target 2.0
				sampler2D _UpTex;
				half4 _UpTex_HDR;
				half4 frag(v2f i) : SV_Target { return skybox_frag(i,_UpTex, _UpTex_HDR); }
				ENDCG
			}
			Pass{
				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma target 2.0
				sampler2D _DownTex;
				half4 _DownTex_HDR;
				half4 frag(v2f i) : SV_Target { return skybox_frag(i,_DownTex, _DownTex_HDR); }
				ENDCG
			}
	}
}