Raymarching in Unity's new SRP & Post Processing V2

Update: more info, including object space culling, found here.

YES!!! After SO many days, so much time spent feeling defeated, I GOT IT!

Many thanks to this blog post and this forum post for giving me clues for the right direction.

Here is the completely hideous working solution to raymarch a sphere in Unity's PostFX V2 stack!

Debug.cs

using System; using UnityEngine; using UnityEngine.Rendering; using UnityEngine.Rendering.PostProcessing; [Serializable] [PostProcess(typeof(DebugRenderer), PostProcessEvent.AfterStack, "Custom/Debug")] public sealed class Debug : PostProcessEffectSettings { public IntParameter maxIterations = new IntParameter { value = 64 }; public FloatParameter maxDistance = new FloatParameter { value = 100f }; public FloatParameter minDistance = new FloatParameter { value = 0.01f }; public DepthTextureMode GetCameraFlags() { return DepthTextureMode.Depth; //| DepthTextureMode.DepthNormals; } } public sealed class DebugRenderer : PostProcessEffectRenderer<Debug> { public override void Render(PostProcessRenderContext context) { Camera _cam = context.camera; var sheet = context.propertySheets.Get(Shader.Find("Hidden/Debug")); sheet.properties.SetMatrix("_CamFrustum", FrustumCorners2(_cam)); sheet.properties.SetMatrix("_CamToWorld", _cam.cameraToWorldMatrix); sheet.properties.SetVector("_CamWorldSpace", _cam.transform.position); sheet.properties.SetInt("_MaxIterations", settings.maxIterations); sheet.properties.SetFloat("_MaxDistance", settings.maxDistance); sheet.properties.SetFloat("_MinDistance", settings.minDistance); context.command.BlitFullscreenTriangle(context.source, context.destination, sheet, 0); } private Matrix4x4 CamFrustum(Camera cam) { Matrix4x4 frustum = Matrix4x4.identity; float fov = Mathf.Tan((cam.fieldOfView * 0.5f) * Mathf.Deg2Rad); Vector3 goUp = Vector3.up * fov; Vector3 goRight = Vector3.right * fov * cam.aspect; Vector3 TL = (-Vector3.forward - goRight + goUp); Vector3 TR = (-Vector3.forward + goRight + goUp); Vector3 BR = (-Vector3.forward + goRight - goUp); Vector3 BL = (-Vector3.forward - goRight - goUp); frustum.SetRow(0, TL); frustum.SetRow(1, TR); frustum.SetRow(2, BR); frustum.SetRow(3, BL); return frustum; } private Matrix4x4 GetFrustumCorners(Camera cam) { float camFov = cam.fieldOfView; float camAspect = cam.aspect; Matrix4x4 frustumCorners = Matrix4x4.identity; float fovWHalf = camFov * 0.5f; float tan_fov = Mathf.Tan(fovWHalf * Mathf.Deg2Rad); Vector3 toRight = Vector3.right * tan_fov * camAspect; Vector3 toTop = Vector3.up * tan_fov; Vector3 topLeft = (-Vector3.forward - toRight + toTop); Vector3 topRight = (-Vector3.forward + toRight + toTop); Vector3 bottomRight = (-Vector3.forward + toRight - toTop); Vector3 bottomLeft = (-Vector3.forward - toRight - toTop); frustumCorners.SetRow(0, topLeft); frustumCorners.SetRow(1, topRight); frustumCorners.SetRow(2, bottomRight); frustumCorners.SetRow(3, bottomLeft); return frustumCorners; } private Matrix4x4 FrustumCorners(Camera cam) { Transform camtr = cam.transform; Vector3[] frustumCorners = new Vector3[4]; cam.CalculateFrustumCorners(new Rect(0, 0, 1, 1), cam.farClipPlane, cam.stereoActiveEye, frustumCorners); var bottomLeft = camtr.TransformVector(frustumCorners[0]); var topLeft = camtr.TransformVector(frustumCorners[1]); var topRight = camtr.TransformVector(frustumCorners[2]); var bottomRight = camtr.TransformVector(frustumCorners[3]); Matrix4x4 frustumCornersArray = Matrix4x4.identity; frustumCornersArray.SetRow(0, bottomLeft); frustumCornersArray.SetRow(1, bottomRight); frustumCornersArray.SetRow(2, topLeft); frustumCornersArray.SetRow(3, topRight); return frustumCornersArray; } private Matrix4x4 FrustumCorners2(Camera cam) { Transform camtr = cam.transform; Vector3[] frustumCorners = new Vector3[4]; cam.CalculateFrustumCorners(new Rect(0, 0, 1, 1), cam.farClipPlane, cam.stereoActiveEye, frustumCorners); var bottomLeft = camtr.TransformVector(frustumCorners[1]); var topLeft = camtr.TransformVector(frustumCorners[0]); var bottomRight = camtr.TransformVector(frustumCorners[2]); Matrix4x4 frustumVectorsArray = Matrix4x4.identity; frustumVectorsArray.SetRow(0, bottomLeft); frustumVectorsArray.SetRow(1, bottomLeft + (bottomRight - bottomLeft) * 2); frustumVectorsArray.SetRow(2, bottomLeft + (topLeft - bottomLeft) * 2); return frustumVectorsArray; } } 

Debug.shader

Shader "Hidden/Debug" { 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" #include "UnityCG.cginc" //TEXTURE2D_SAMPLER2D(_MainTex, sampler_MainTex); uniform sampler2D _MainTex; uniform sampler2D_float _CameraDepthTexture, sampler_CameraDepthTexture; half4 _MainTex_ST; uniform float4 _CamWorldSpace; uniform float4x4 _CamFrustum, _CamToWorld; uniform int _MaxIterations; uniform float _MaxDistance; uniform float _MinDistance; float4 _Tint; uniform float4 _MainTex_TexelSize; struct AttributesDefault { float3 vertex : POSITION; half2 texcoord : TEXCOORD0; }; struct VaryingsDefault { float4 pos : SV_POSITION; float2 uv : TEXCOORD0; float2 uvStereo : TEXCOORD4; //float2 uvStereo : TEXCOORD1; float2 uv_depth : TEXCOORD1; float4 interpolatedRay : TEXCOORD2; float3 wPos : TEXCOORD3; }; struct v2f { float4 vertex : SV_POSITION; float2 texcoord : TEXCOORD0; float2 texcoordStereo : TEXCOORD1; float4 ray : TEXCOORD2; }; float LinearEyeDepth135( float z ) { return LinearEyeDepth( z ); } // Vertex manipulation float2 TransformTriangleVertexToUV(float2 vertex) { float2 uv = (vertex + 1.0) * 0.5; return uv; } //VaryingsDefault vert(AttributesDefault v ) //{ // VaryingsDefault o; // v.vertex.z = 0.1; // o.wPos = mul(UNITY_MATRIX_VP, v.vertex); // o.pos = float4(v.vertex.xy, 0.0, 1.0); // o.uv = TransformTriangleVertexToUV(v.vertex.xy); // o.uv_depth = v.texcoord.xy; // #if UNITY_UV_STARTS_AT_TOP // o.uv = o.uv * float2(1.0, -1.0) + float2(0.0, 1.0); // #endif // o.uvStereo = TransformStereoScreenSpaceTex(o.uv, 1.0); // #if UNITY_UV_STARTS_AT_TOP // if (_MainTex_TexelSize.y < 0) // o.uv.y = 1 - o.uv.y; // #endif // //int frustumIndex = v.texcoord.x + (2 * o.uv.y); // //o.interpolatedRay = _CamFrustum[frustumIndex]; // //o.interpolatedRay.w = frustumIndex; // int index = (o.uv.x / 2) + o.uv.y; // o.interpolatedRay = _CamFrustum[index]; // //o.interpolatedRay /= abs(o.interpolatedRay.z); // //o.interpolatedRay = mul(_CamToWorld, o.interpolatedRay); // return o; //} v2f vert(AttributesDefault v ) { v2f o; v.vertex.z = 0.1; //o.vertex = mul(UNITY_MATRIX_VP, v.vertex); 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); //#if UNITY_UV_STARTS_AT_TOP // if (_MainTex_TexelSize.y < 0) // o.texcoord.y = 1 - o.texcoord.y; //#endif //int index = v.texcoord.x + (2 * o.texcoord.y); int index = (o.texcoord.x / 2) + o.texcoord.y; o.ray = _CamFrustum[index]; return o; } float sdSphere(float3 position, float3 origin, float radius) { return distance(position, origin) - radius; } float sdf_sphere(float3 p, float3 c, float r) { return distance(p, c) - r; } fixed4 raymarching(float3 rayOrigin, float3 rayDirection) { fixed4 result = float4(1, 1, 1, 1); float t = 0.01; // Distance Traveled from ray origin (ro) along the ray direction (rd) for (int i = 0; i < _MaxIterations; i++) { if (t > _MaxDistance) { result = float4(rayDirection, 1); // color backround from ray direction for debugging break; } float3 p = rayOrigin + rayDirection * t; // This is our current position //float3 p = float3(5, 0, 0) + (float3(1, 0, 0) * t); // This is our current position //float d = sdSphere(p, float3(1, 0, 0), 2); // should be a sphere at (0, 0, 0) with a radius of 1 float d = sdf_sphere(p, float3(0, 0, 0), 1); if (d <= _MinDistance) // We have hit something { // shading result = float4(1, 1, 1, 1); // yellow sphere should be drawn at (0, 0, 0) break; } //t += max(0.01, 0.02 * 2); t += d; } return result; } fixed4 rm (float3 ro, float3 rd) { fixed4 result = float4(0, 0, 0, 1); float t = 0; for (int i = 0; i < 100; i++) { float3 p = ro + rd * t; float d = sdf_sphere(p, float3(0, 0, 0), 0.8); if (d <= _MinDistance) // We have hit something { // shading result = float4(1, 1, 0, 1); // yellow sphere should be drawn at (0, 0, 0) break; } t += d; } return result; } float4 frag(v2f i) : SV_Target { //float rawDepth = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, UnityStereoTransformScreenSpaceTex(i.uv )); //float dpth = Linear01Depth(rawDepth); //float depth = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, sampler_CameraDepthTexture, i.uvStereo); //depth = Linear01Depth(depth); //float rawDepth = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, i.uvStereo); //float dpth = Linear01Depth(rawDepth); ////float4 wsDir = normalize(i.interpolatedRay); //float3 wsDir = normalize(i.interpolatedRay); //float4 wsPos = _CamWorldSpace; ////fixed4 result = raymarching(_CamWorldSpace, normalize(i.interpolatedRay.xyz)); //fixed4 result = rm(_CamWorldSpace, normalize(i.interpolatedRay.xyz)); //return result; //float dpth = Linear01Depth(rawDepth); //return raymarching(_WorldSpaceCameraPos, normalize(i.interpolatedRay)); return raymarching(_CamWorldSpace, normalize(i.ray)); //half4 sceneColor = tex2D(_MainTex, UnityStereoTransformScreenSpaceTex(i.uv)); //// Reconstruct world space position & direction //// towards this screen pixel. //float rawDepth = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, UnityStereoTransformScreenSpaceTex(i.uv )); //float dpth = Linear01Depth(rawDepth); //float4 wsDir = dpth * i.interpolatedRay; //float4 wsPos = _CamWorldSpace + wsDir; //return wsPos; //return raymarching(wsPos, wsDir); } ENDHLSL } } }