Vulkan: fix hack, allow SSAO to read from all mips.

When we overhauled image layout transitions, we moved as many
transitions as possible into the render pass. However the transition
that we perform for "depth read only" layout needs to be applied to
multiple miplevels, so we cannot use the render pass for that.

filament/backend/src/vulkan/VulkanContext.h

@@ -57,9 +57,8 @@ struct VulkanTimestamps {
 
 struct VulkanRenderPass {
     VkRenderPass renderPass;
-    uint32_t subpassMask;
+    RenderPassParams params;
     int currentSubpass;
-    VulkanTexture* depthFeedback;
 };
 
 // For now we only support a single-device, single-instance scenario. Our concept of "context" is a

filament/backend/src/vulkan/VulkanDriver.cpp

@@ -1020,6 +1020,9 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
     // Sometimes we need to permit the shader to sample the depth attachment by transitioning the
     // layout of all its subresources to a read-only layout. This is especially crucial for SSAO.
     //
+    // We cannot perform this transition using the render pass because the shaders in this render
+    // pass might sample from multiple miplevels.
+    //
     // We do not use GENERAL here due to the following validation message:
     //
     //   The Vulkan spec states: Image subresources used as attachments in the current render pass
@@ -1031,7 +1034,15 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
     //
     if (params.readOnlyDepthStencil & RenderPassParams::READONLY_DEPTH) {
         depthFeedback = depth.texture;
-        renderPassDepthLayout = VulkanDepthLayout::READ_ONLY;
+        VkImageSubresourceRange range = {
+            .aspectMask = VK_IMAGE_ASPECT_DEPTH_BIT,
+            .baseMipLevel = 0,
+            .levelCount = depth.texture->levels,
+            .baseArrayLayer = 0,
+            .layerCount = depth.texture->depth,
+        };
+        depth.texture->transitionLayout(cmdbuffer, range, VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL);
+        initialDepthLayout = renderPassDepthLayout = finalDepthLayout = VulkanDepthLayout::READ_ONLY;
     }
 
     if (depth.texture) {
@@ -1175,9 +1186,8 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
 
     mContext.currentRenderPass = {
         .renderPass = renderPassInfo.renderPass,
-        .subpassMask = params.subpassMask,
+        .params = params,
         .currentSubpass = 0,
-        .depthFeedback = depthFeedback
     };
 }
 
@@ -1187,14 +1197,18 @@ void VulkanDriver::endRenderPass(int) {
 
     assert_invariant(mCurrentRenderTarget);
 
-    // In most cases, the image layout used during the render pass is the same as "finalLayout".
-    // i.e. there is no transition at the end. However one exception is depth, which can sometimes
-    // be transitioned from DEPTH_STENCIL_READ_ONLY_OPTIMAL to GENERAL. Here we detect this case
-    // and notify the texture wrapper for proper tracking.
-    VulkanTexture* depthFeedbackTexture = mContext.currentRenderPass.depthFeedback;
-    if (depthFeedbackTexture) {
+    // In some cases, depth needs to be transitioned from DEPTH_STENCIL_READ_ONLY_OPTIMAL back to
+    // GENERAL. We did not do this using the render pass because we need to change multiple mips.
+    if (mContext.currentRenderPass.params.readOnlyDepthStencil & RenderPassParams::READONLY_DEPTH) {
         const VulkanAttachment& depth = mCurrentRenderTarget->getDepth();
-        depthFeedbackTexture->trackLayout(depth.level, depth.layer,
+        VkImageSubresourceRange range = {
+            .aspectMask = VK_IMAGE_ASPECT_DEPTH_BIT,
+            .baseMipLevel = 0,
+            .levelCount = depth.texture->levels,
+            .baseArrayLayer = 0,
+            .layerCount = depth.texture->depth,
+        };
+        depth.texture->transitionLayout(cmdbuffer, range,
                 getDefaultImageLayout(TextureUsage::DEPTH_ATTACHMENT));
     }
 
@@ -1241,7 +1255,7 @@ void VulkanDriver::nextSubpass(int) {
             "Only two subpasses are currently supported.");
 
     assert_invariant(mCurrentRenderTarget);
-    assert_invariant(mContext.currentRenderPass.subpassMask);
+    assert_invariant(mContext.currentRenderPass.params.subpassMask);
 
     vkCmdNextSubpass(mContext.commands->get().cmdbuffer, VK_SUBPASS_CONTENTS_INLINE);
 
@@ -1249,7 +1263,7 @@ void VulkanDriver::nextSubpass(int) {
             ++mContext.currentRenderPass.currentSubpass);
 
     for (uint32_t i = 0; i < VulkanPipelineCache::TARGET_BINDING_COUNT; i++) {
-        if ((1 << i) & mContext.currentRenderPass.subpassMask) {
+        if ((1 << i) & mContext.currentRenderPass.params.subpassMask) {
             VulkanAttachment subpassInput = mCurrentRenderTarget->getColor(i);
             VkDescriptorImageInfo info = {
                 .imageView = subpassInput.getImageView(VK_IMAGE_ASPECT_COLOR_BIT),
@@ -1787,19 +1801,6 @@ void VulkanDriver::draw(PipelineState pipelineState, Handle<HwRenderPrimitive> r
                 .imageView = texture->getPrimaryImageView(),
                 .imageLayout = texture->getPrimaryImageLayout()
             };
-
-            // TODO: it should not be necessary to use a custom image view here, instead we should
-            // transition all levels that need to be transitioned.
-            if (mContext.currentRenderPass.depthFeedback == texture) {
-                VkImageSubresourceRange range = {
-                    .aspectMask = VK_IMAGE_ASPECT_DEPTH_BIT,
-                    .baseMipLevel = 0,
-                    .levelCount = 1,
-                    .baseArrayLayer = 0,
-                    .layerCount = 1,
-                };
-                iInfo[bindingPoint].imageView = texture->getImageView(range);
-            }
         }
     }
 

filament/backend/src/vulkan/VulkanHandles.cpp

@@ -214,7 +214,7 @@ int VulkanRenderTarget::getColorTargetCount(const VulkanRenderPass& pass) const
             continue;
         }
         // NOTE: This must be consistent with VkRenderPass construction (see VulkanFboCache).
-        if (!(pass.subpassMask & (1 << i)) || pass.currentSubpass == 1) {
+        if (!(pass.params.subpassMask & (1 << i)) || pass.currentSubpass == 1) {
             count++;
         }
     }

filament/backend/src/vulkan/VulkanUtility.cpp

@@ -601,6 +601,7 @@ VulkanLayoutTransition textureTransitionHelper(VulkanLayoutTransition transition
             break;
         case VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL:
         case VK_IMAGE_LAYOUT_GENERAL:
+        case VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL:
             transition.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
             transition.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
             transition.srcStage = VK_PIPELINE_STAGE_TRANSFER_BIT;