DoF: don't rely on texture swizzle being supported

filament/CMakeLists.txt

@@ -163,6 +163,7 @@ set(MATERIAL_SRCS
         src/materials/dof/dofDownsample.mat
         src/materials/dof/dofCombine.mat
         src/materials/dof/dofTiles.mat
+        src/materials/dof/dofTilesSwizzle.mat
         src/materials/dof/dofDilate.mat
         src/materials/dof/dofMipmap.mat
         src/materials/dof/dofMedian.mat

filament/backend/src/metal/MetalDriver.mm

@@ -551,6 +551,7 @@ bool MetalDriver::isTextureFormatSupported(TextureFormat format) {
 }
 
 bool MetalDriver::isTextureSwizzleSupported() {
+    return false; // FIXME: reenable once textures used as attachments are supported
     if (@available(macOS 10.15, iOS 13, *)) {
         return true;
     } else {

filament/src/PostProcessManager.cpp

@@ -212,6 +212,7 @@ static const MaterialInfo sMaterialList[] = {
         { "dofCoc",                MATERIAL(DOFCOC) },
         { "dofMipmap",             MATERIAL(DOFMIPMAP) },
         { "dofTiles",              MATERIAL(DOFTILES) },
+        { "dofTilesSwizzle",       MATERIAL(DOFTILESSWIZZLE) },
         { "dofDilate",             MATERIAL(DOFDILATE) },
         { "dof",                   MATERIAL(DOF) },
         { "dofMedian",             MATERIAL(DOFMEDIAN) },
@@ -1064,6 +1065,7 @@ FrameGraphId<FrameGraphTexture> PostProcessManager::dof(FrameGraph& fg,
         FrameGraphId<FrameGraphTexture> outTilesCocMinMax;
     };
 
+    const bool textureSwizzleSupported = Texture::isTextureSwizzleSupported(mEngine);
     for (size_t i = 0; i < tileReductionCount; i++) {
         auto& ppDoFTiling = fg.addPass<PostProcessDofTiling1>("DoF Tiling",
                 [&](FrameGraph::Builder& builder, auto& data) {
@@ -1083,7 +1085,9 @@ FrameGraphId<FrameGraphTexture> PostProcessManager::dof(FrameGraph& fg,
                     auto const& outputDesc = resources.getDescriptor(data.outTilesCocMinMax);
                     auto const& out = resources.getRenderPassInfo();
                     auto inCocMinMax = resources.getTexture(data.inCocMinMax);
-                    auto const& material = getPostProcessMaterial("dofTiles");
+                    auto const& material = (!textureSwizzleSupported && (i == 0)) ?
+                            getPostProcessMaterial("dofTilesSwizzle") :
+                            getPostProcessMaterial("dofTiles");
                     FMaterialInstance* const mi = material.getMaterialInstance();
                     mi->setParameter("cocMinMax", inCocMinMax, { .filterMin = SamplerMinFilter::NEAREST });
                     mi->setParameter("uvscale", float4{

filament/src/materials/dof/dofTiles.mat

@@ -47,6 +47,7 @@ void postProcess(inout PostProcessInputs postProcess) {
     ivec2 i = ivec2(uv * size - 0.5);
 
     // note: the first time, the source texture is swizzled -- so .r and .g are the same channel
+    // if swizzling is not supported, we use dofTilesSwizzle instead.
 #if defined(TARGET_VULKAN_ENVIRONMENT) || !defined(TARGET_MOBILE)
     vec4 mi = textureGather(materialParams_cocMinMax, uv, 0); // 01, 11, 10, 00
     vec4 ma = textureGather(materialParams_cocMinMax, uv, 1); // 01, 11, 10, 00

filament/src/materials/dof/dofTilesSwizzle.mat

@@ -0,0 +1,66 @@
+material {
+    name : dofTilesSwizzle,
+    parameters : [
+        {
+            type : sampler2d,
+            name : cocMinMax,
+            precision: medium
+        },
+        {
+            type : float4,
+            name : uvscale,
+            precision: high
+        }
+    ],
+    variables : [
+        vertex
+    ],
+    domain : postprocess,
+    depthWrite : false,
+    depthCulling : false
+}
+
+vertex {
+    void postProcessVertex(inout PostProcessVertexInputs postProcess) {
+        postProcess.vertex.xy = (postProcess.normalizedUV * materialParams.uvscale.xy * 2.0 - 0.5) * materialParams.uvscale.zw;
+    }
+}
+
+fragment {
+
+void dummy(){}
+
+float max4(const vec4 f) {
+    vec2 t = max(f.xy, f.zw);
+    return max(t.x, t.y);
+}
+
+float min4(const vec4 f) {
+    vec2 t = min(f.xy, f.zw);
+    return min(t.x, t.y);
+}
+
+void postProcess(inout PostProcessInputs postProcess) {
+    highp vec2 uv = variable_vertex.xy;
+    highp vec2 size = vec2(textureSize(materialParams_cocMinMax, 0));
+
+    ivec2 i = ivec2(uv * size - 0.5);
+
+#if defined(TARGET_VULKAN_ENVIRONMENT) || !defined(TARGET_MOBILE)
+    vec4 mi = textureGather(materialParams_cocMinMax, uv, 0); // 01, 11, 10, 00
+#else
+    vec4 mi;
+    mi[0] = texelFetchOffset(materialParams_cocMinMax, i, 0, ivec2(0, 1)).r;
+    mi[1] = texelFetchOffset(materialParams_cocMinMax, i, 0, ivec2(1, 1)).r;
+    mi[2] = texelFetchOffset(materialParams_cocMinMax, i, 0, ivec2(1, 0)).r;
+    mi[3] = texelFetchOffset(materialParams_cocMinMax, i, 0, ivec2(0, 0)).r;
+#endif
+
+    // compute tile's min CoC
+    postProcess.color.r = min4(mi);
+
+    // compute tile's max CoC
+    postProcess.color.g = max4(mi);
+}
+
+}