Vulkan: Fix HDR render pass mismatch and pipeline barrier

Fix render pass / framebuffer format mismatch when rendering through
the SDR offscreen buffer in HDR mode. The filter chain's final pass
and the frame render pass were using vk->render_pass (A2B10G10R10)
while the offscreen buffer framebuffer was created with
vk->sdr_render_pass (B8G8R8A8), causing a Vulkan validation error.

Select the correct render pass at frame time based on
use_offscreen_buffer, and rebuild the filter chain's final pass
pipeline to use the SDR render pass both at shader preset load and
at swapchain recreation.

Also fix an incorrect srcStageMask in the image layout transition
after the HDR pipeline: SHADER_READ_BIT requires FRAGMENT_SHADER_BIT,
not COLOR_ATTACHMENT_OUTPUT_BIT.

Author: MajorPainTheCactus

gfx/drivers/vulkan.c

@@ -3307,6 +3307,20 @@ static bool vulkan_init_filter_chain_preset(vk_t *vk, const char *shader_path)
          vulkan_set_hdr_inverse_tonemap(vk, vk->filter_chain, !emits_hdr10);
          vulkan_set_hdr10(vk, vk->filter_chain, !emits_hdr10);
          vk->flags |= VK_FLAG_SHOULD_RESIZE;
+
+         if (!emits_hdr10)
+         {
+            /* Rendering goes through the SDR offscreen buffer;
+             * rebuild the filter chain's final pass pipeline
+             * to use the SDR render pass. */
+            struct vulkan_filter_chain_swapchain_info sdr_swapchain;
+            sdr_swapchain.vp          = vk->vk_vp;
+            sdr_swapchain.format      = vk->context->swapchain_format;
+            sdr_swapchain.render_pass = vk->sdr_render_pass;
+            sdr_swapchain.num_indices = vk->context->num_swapchain_images;
+            vulkan_filter_chain_update_swapchain_info(
+                  vk->filter_chain, &sdr_swapchain);
+         }
       }
       else if (rt_format == VK_FORMAT_R16G16B16A16_SFLOAT)
       {
@@ -4032,6 +4046,26 @@ static void vulkan_check_swapchain(vk_t *vk)
    filter_info.format               = vk->context->swapchain_format;
    filter_info.render_pass          = vk->render_pass;
    filter_info.num_indices          = vk->context->num_swapchain_images;
+
+#ifdef VULKAN_HDR_SWAPCHAIN
+   /* When rendering through the SDR offscreen buffer, the filter chain's
+    * final pass must use the SDR render pass to match the framebuffer format. */
+   if (vk->context->flags & VK_CTX_FLAG_HDR_ENABLE)
+   {
+      vulkan_filter_chain_t *chain   = vk->filter_chain
+         ? vk->filter_chain : vk->filter_chain_default;
+      struct video_shader *preset    = vulkan_filter_chain_get_preset(chain);
+      if (preset && preset->passes)
+      {
+         VkFormat rt_format = vulkan_filter_chain_get_pass_rt_format(
+               chain, preset->passes - 1);
+         if (  vulkan_is_hdr10_format(rt_format)
+            && !vulkan_filter_chain_emits_hdr10(chain))
+            filter_info.render_pass = vk->sdr_render_pass;
+      }
+   }
+#endif
+
    if (
        !vulkan_filter_chain_update_swapchain_info(
           (vk->filter_chain) ? vk->filter_chain : vk->filter_chain_default,
@@ -5115,7 +5149,12 @@ static bool vulkan_frame(void *data, const void *frame,
    {
       rp_info.sType                    = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
       rp_info.pNext                    = NULL;
+#ifdef VULKAN_HDR_SWAPCHAIN
+      rp_info.renderPass               = use_offscreen_buffer
+         ? vk->sdr_render_pass : vk->render_pass;
+#else
       rp_info.renderPass               = vk->render_pass;
+#endif
       rp_info.framebuffer              = backbuffer->framebuffer;
       rp_info.renderArea.offset.x      = 0;
       rp_info.renderArea.offset.y      = 0;
@@ -5163,7 +5202,7 @@ static bool vulkan_frame(void *data, const void *frame,
          VULKAN_IMAGE_LAYOUT_TRANSITION(vk->cmd, vk->offscreen_buffer.image,
                VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
                VK_ACCESS_SHADER_READ_BIT, VK_ACCESS_TRANSFER_WRITE_BIT,
-               VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
+               VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT,
                VK_PIPELINE_STAGE_TRANSFER_BIT);
 
          end_main_pass = false;