RaymarchHDRP.shader

Shader "Raymarch/RaymarchHDRP"
{

    SubShader
    {
        Cull Off ZWrite Off ZTest Always

        Pass
        {
            HLSLPROGRAM

			#pragma target 3.5

                        #pragma vertex vert
			#pragma fragment frag

			#include "Packages/com.unity.postprocessing/PostProcessing/Shaders/StdLib.hlsl"
			#include "HLSLSupport.cginc"

			TEXTURE2D_SAMPLER2D(_MainTex, sampler_MainTex);
			half4 _MainTex_ST;
			uniform float4 _CamWorldSpace;
			uniform float4x4 _CamFrustum,  _CamToWorld;
			uniform int _MaxIterations;
			uniform float _MaxDistance;
			uniform float _MinDistance;
			float4 _Tint;

			#define UNITY_MATRIX_MVP mul(unity_MatrixVP, unity_ObjectToWorld)

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

			struct v2f
			{
				float4 vertex : SV_POSITION;
				float2 texcoord : TEXCOORD0;
				float2 texcoordStereo : TEXCOORD1;
				float3 ray : TEXCOORD2;
			};

			v2f vert(AttributesDefault v)
			{
				v2f o;
				half index = v.vertex.z;
				o.vertex = float4(v.vertex.xy, 0.0, 1.0);
				o.texcoord = TransformTriangleVertexToUV(v.vertex.xy);

				#if UNITY_UV_STARTS_AT_TOP
					o.texcoord = o.texcoord * float2(1.0, -1.0) + float2(0.0, 1.0);
				#endif

				o.texcoordStereo = TransformStereoScreenSpaceTex(o.texcoord, 1.0);

				o.ray = _CamFrustum[(int)index].xyz;
				o.ray /= abs(o.ray.z);
				o.ray = mul(_CamToWorld, o.ray);

				return o;
			}

			float sdSphere(float3 position, float3 origin, float radius)
			{
				return distance(position, origin) - radius;
			}

			fixed4 raymarching(float3 ro, float3 rd) {
				fixed4 result = float4(1, 1, 1, 1);
				float t = 0; // Distance Traveled from ray origin (ro) along the ray direction (rd)

				for (int i = 0; i < _MaxIterations; i++)
				{
					if (t > _MaxDistance)
					{
						// todo: draw environment
						result = float4(rd, 1);
						break;
					}

					float3 p = ro + rd * t;	// This is our current position
					float d = sdSphere(p, float3(0, 0, 0), 1.0);
					if (d <= _MinDistance) // We have hit something
					{
						// shading
						result = float4(0.2, 0.2, 0.2, 1);
						break;
					}

					t += d;
				}

				return result;
			}

			float4 frag(v2f i) : SV_Target
			{
				float3 rayDirection = normalize(i.ray.xyz);
				float3 rayOrigin = _WorldSpaceCameraPos;
				fixed4 result = raymarching(rayOrigin, rayDirection);
				return result;
			}

            ENDHLSL
        }
    }
}