Added a temporary RT abstraction layer

This isn't pretty but will do just fine until we can get a better abstraction layer on top of (or better yet, in place of) the current render texture stuff.

ScriptableRenderPipeline/Core/CoreRP/RTHandle.cs

+using System.Collections.Generic;
+using UnityEngine.Rendering;
+
+namespace UnityEngine.Experimental.Rendering
+{
+    public delegate Vector2Int ScaleFunc(Vector2Int size);
+
+    public enum DepthBits
+    {
+        None = 0,
+        Depth8 = 8,
+        Depth16 = 16,
+        Depth24 = 24
+    }
+
+    public enum MSAASamples
+    {
+        None = 1,
+        MSAA2x = 2,
+        MSAA4x = 4,
+        MSAA8x = 8
+    }
+
+    public class RTHandle
+    {
+        public static int s_MaxWidth { get; private set; }
+        public static int s_MaxHeight { get; private set; }
+
+        static List<RTHandle> s_AutoSizedRTs;
+
+        public RenderTexture rt { get; private set; }
+        public RenderTargetIdentifier nameID;
+
+        Vector2 scaleFactor = Vector2.one;
+        ScaleFunc scaleFunc;
+
+        static RTHandle()
+        {
+            s_AutoSizedRTs = new List<RTHandle>();
+            s_MaxWidth = 1;
+            s_MaxHeight = 1;
+        }
+
+        RTHandle(RenderTexture rt)
+        {
+            this.rt = rt;
+            nameID = new RenderTargetIdentifier(rt);
+        }
+
+        public void Release()
+        {
+            s_AutoSizedRTs.Remove(this);
+            CoreUtils.Destroy(rt);
+            rt = null;
+            nameID = BuiltinRenderTextureType.None;
+        }
+
+        public static void Release(RTHandle rth)
+        {
+            rth.Release();
+        }
+
+        public static void SetReferenceSize(int width, int height)
+        {
+            width = Mathf.Max(width, 1);
+            height = Mathf.Max(height, 1);
+
+            if (width > s_MaxWidth || height > s_MaxHeight)
+                Resize(width, height);
+        }
+
+        public static void ResetReferenceSize(int width, int height)
+        {
+            width = Mathf.Max(width, 1);
+            height = Mathf.Max(height, 1);
+
+            if (width != s_MaxWidth || height != s_MaxHeight)
+                Resize(width, height);
+        }
+
+        static void Resize(int width, int height)
+        {
+            s_MaxWidth = width;
+            s_MaxHeight = height;
+            var maxSize = new Vector2Int(s_MaxWidth, s_MaxHeight);
+
+            foreach (var rth in s_AutoSizedRTs)
+            {
+                var rt = rth.rt;
+                rt.Release();
+
+                Vector2Int scale;
+
+                if (rth.scaleFunc != null)
+                {
+                    scale = rth.scaleFunc(maxSize);
+                }
+                else
+                {
+                    scale = new Vector2Int(
+                        x: Mathf.RoundToInt(rth.scaleFactor.x * s_MaxWidth),
+                        y: Mathf.RoundToInt(rth.scaleFactor.y * s_MaxHeight)
+                    );
+                }
+
+                rt.width = Mathf.Max(scale.x, 1);
+                rt.height = Mathf.Max(scale.y, 1);
+                rt.Create();
+            }
+        }
+
+        public static RTHandle Alloc(
+                int width,
+                int height,
+                int slices                         = 1,
+                DepthBits depthBufferBits          = DepthBits.None,
+                RenderTextureFormat colorFormat    = RenderTextureFormat.Default,
+                FilterMode filterMode              = FilterMode.Point,
+                TextureWrapMode wrapMode           = TextureWrapMode.Repeat,
+                TextureDimension dimension         = TextureDimension.Tex2D,
+                bool sRGB                          = true,
+                bool enableRandomWrite             = false,
+                bool useMipMap                     = false,
+                bool autoGenerateMips              = true,
+                int anisoLevel                     = 1,
+                float mipMapBias                   = 0f,
+                MSAASamples msaaSamples            = MSAASamples.None,
+                bool bindTextureMS                 = false,
+                bool useDynamicScale               = false,
+                VRTextureUsage vrUsage             = VRTextureUsage.None,
+                RenderTextureMemoryless memoryless = RenderTextureMemoryless.None
+            )
+        {
+            var rt = new RenderTexture(width, height, (int)depthBufferBits, colorFormat, sRGB ? RenderTextureReadWrite.sRGB : RenderTextureReadWrite.Linear)
+            {
+                hideFlags = HideFlags.HideAndDontSave,
+                volumeDepth = slices,
+                filterMode = filterMode,
+                wrapMode = wrapMode,
+                dimension = dimension,
+                enableRandomWrite = enableRandomWrite,
+                useMipMap = useMipMap,
+                autoGenerateMips = autoGenerateMips,
+                anisoLevel = anisoLevel,
+                mipMapBias = mipMapBias,
+                antiAliasing = (int)msaaSamples,
+                bindTextureMS = bindTextureMS,
+                useDynamicScale = useDynamicScale,
+                vrUsage = vrUsage,
+                memorylessMode = memoryless
+            };
+            rt.Create();
+
+            return new RTHandle(rt);
+        }
+
+        public static RTHandle Alloc(
+                Vector2 scaleFactor,
+                DepthBits depthBufferBits          = DepthBits.None,
+                RenderTextureFormat colorFormat    = RenderTextureFormat.Default,
+                FilterMode filterMode              = FilterMode.Point,
+                TextureWrapMode wrapMode           = TextureWrapMode.Repeat,
+                TextureDimension dimension         = TextureDimension.Tex2D,
+                bool sRGB                          = true,
+                bool enableRandomWrite             = false,
+                bool useMipMap                     = false,
+                bool autoGenerateMips              = true,
+                int anisoLevel                     = 1,
+                float mipMapBias                   = 0f,
+                MSAASamples msaaSamples            = MSAASamples.None,
+                bool bindTextureMS                 = false,
+                bool useDynamicScale               = false,
+                VRTextureUsage vrUsage             = VRTextureUsage.None,
+                RenderTextureMemoryless memoryless = RenderTextureMemoryless.None
+            )
+        {
+            int width = Mathf.Max(Mathf.RoundToInt(scaleFactor.x * s_MaxWidth), 1);
+            int height = Mathf.Max(Mathf.RoundToInt(scaleFactor.y * s_MaxHeight), 1);
+
+            var rth = Alloc(width,
+                height,
+                1,
+                depthBufferBits,
+                colorFormat,
+                filterMode,
+                wrapMode,
+                dimension,
+                sRGB,
+                enableRandomWrite,
+                useMipMap,
+                autoGenerateMips,
+                anisoLevel,
+                mipMapBias,
+                msaaSamples,
+                bindTextureMS,
+                useDynamicScale,
+                vrUsage,
+                memoryless
+            );
+
+            rth.scaleFactor = scaleFactor;
+            s_AutoSizedRTs.Add(rth);
+            return rth;
+        }
+
+        //
+        // You can provide your own scaling function for advanced scaling schemes (e.g. scaling to
+        // the next POT). The function takes a Vec2 as parameter that holds max width & height
+        // values for the current manager context and returns a Vec2 of the final size in pixels.
+        //
+        // var rth = Alloc(
+        //     size => new Vector2Int(size.x / 2, size.y),
+        //     [...]
+        // );
+        //
+        public static RTHandle Alloc(
+                ScaleFunc scaleFunc,
+                DepthBits depthBufferBits          = DepthBits.None,
+                RenderTextureFormat colorFormat    = RenderTextureFormat.Default,
+                FilterMode filterMode              = FilterMode.Point,
+                TextureWrapMode wrapMode           = TextureWrapMode.Repeat,
+                TextureDimension dimension         = TextureDimension.Tex2D,
+                bool sRGB                          = true,
+                bool enableRandomWrite             = false,
+                bool useMipMap                     = false,
+                bool autoGenerateMips              = true,
+                int anisoLevel                     = 1,
+                float mipMapBias                   = 0f,
+                MSAASamples msaaSamples            = MSAASamples.None,
+                bool bindTextureMS                 = false,
+                bool useDynamicScale               = false,
+                VRTextureUsage vrUsage             = VRTextureUsage.None,
+                RenderTextureMemoryless memoryless = RenderTextureMemoryless.None
+            )
+        {
+            var scaleFactor = scaleFunc(new Vector2Int(s_MaxWidth, s_MaxHeight));
+            int width = Mathf.Max(scaleFactor.x, 1);
+            int height = Mathf.Max(scaleFactor.y, 1);
+
+            var rth = Alloc(width,
+                height,
+                1,
+                depthBufferBits,
+                colorFormat,
+                filterMode,
+                wrapMode,
+                dimension,
+                sRGB,
+                enableRandomWrite,
+                useMipMap,
+                autoGenerateMips,
+                anisoLevel,
+                mipMapBias,
+                msaaSamples,
+                bindTextureMS,
+                useDynamicScale,
+                vrUsage,
+                memoryless
+            );
+
+            rth.scaleFunc = scaleFunc;
+            s_AutoSizedRTs.Add(rth);
+            return rth;
+        }
+
+        public static implicit operator RenderTexture(RTHandle handle)
+        {
+            return handle.rt;
+        }
+
+        public static implicit operator RenderTargetIdentifier(RTHandle handle)
+        {
+            return handle.nameID;
+        }
+    }
+}

ScriptableRenderPipeline/Core/CoreRP/RTHandle.cs.meta

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