Shader "Kinect/OpticalFlowDebugShader"
{
	Properties
	{
		_Size("Size", Range(0, 100)) = 1
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100
		//Cull Off

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma geometry geom
			#pragma fragment frag
			
			#include "UnityCG.cginc"
			
			#ifdef SHADER_API_D3D11
			StructuredBuffer<float4> KinectPositionBuffer;
			StructuredBuffer<float4> KinectVelocityBuffer;
			#endif

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2g
			{
				//float4 vertex : SV_POSITION;
				//float2 uv : TEXCOORD0;
				uint id : BLENDINDICES;
				//UNITY_FOG_COORDS(1)
			};

			struct g2f
			{
				float4 vertex : SV_POSITION;
				float3 color : COLOR;
			};

			float _Size;
			float colorize;
			
			v2g vert(appdata_base v, uint vid : SV_VertexID)
			{
				v2g o = (v2g)0;
				o.id = vid;
				return o;
			}

			[maxvertexcount(2)]
			void geom(point v2g input[1], inout LineStream<g2f> OutputStream)
			{
				#ifdef SHADER_API_D3D11
				float4 position = KinectPositionBuffer[input[0].id];
				float4 velocity = KinectVelocityBuffer[input[0].id];
				#else
				float4 position = float4(0, 0, 0, 1);
				float4 velocity = float4(0, 0, 0, 0);
				#endif

				float3 c0 = float3(0, 1, 0);
				float3 c1 = float3(1, 0, 0);
				c0 = float3(237, 210, 152) / 255;
				c1 = float3(3, 46, 82) / 255;
				
				g2f o = (g2f)0;

				o.vertex = UnityObjectToClipPos(position.xyz);
				o.color = lerp(float3(0, 0, 0), c0, colorize);
				OutputStream.Append(o);

				o.vertex = UnityObjectToClipPos(position.xyz - velocity.xyz * _Size);
				o.color = lerp(float3(0, 0, 0), c1, colorize);
				OutputStream.Append(o);

				OutputStream.RestartStrip();
			}
			
			fixed4 frag (g2f i) : SV_Target
			{
				fixed4 col = float4(i.color, 1.0f);
				return col;
			}
			ENDCG
		}
	}
}