Progress Today

In the middle of:

• Drawing a triangle --> Drawing --> Rendering and presentation

Here are some major takeaways

1. There are two ways of synchronizing swap chain events: fences and semaphores.

• They're both objects that can be used for coordinating ops by having one operation signal and another op wait for a fence or semaphore to signal.
• Fences are mainly designed to sync your app itself with the rendering operation.
  • Fences can be accessed from your program using calls like vkWaitForFences.
• Semaphores are used to sync operations within or across command queues.
  • We want to sync the queue ops of draw commands and presentation, so semaphores are the best fit for this tutorial.

2. To draw a frame, the function in the tutorial will do 3 things:

• Acquire an image from the swap chain.
• Execute the command buffer with that image as the attachment in the framebuffer.
• Return the image to the swap chain for presentation.

3. Subpasses in a render pass automatically take care of image layout transitions, and these transitions are controlled by subpass dependencies.

• subpass dependencies specify memory and execution dependencies between subpasses.
• At this point in the tutorial, we only have 1 subpass, but the operations right before and after are implicit subpasses.
• There are 2 built-in dependencies that take care of the transition at the start of the render pass and at the end, but the transition at the start doesn't happen at the right time.
  • It assumes the transition occurs at the start of the pipeline, but we haven't gotten the image yet at this point.
  • SO! We have to deal with this either by:
    • Modifying the waitStages for the imageAvailableSemaphore to VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT to make sure the render passes don't begin until the image is ready.
    • Make the render pass wait for the VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT stage. For this tutorial, we are using this option.

See ya!

Got distracted with family things, so I wasn't able to finish this page today.