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Fix duplicate device-extension docs and Frames-in-flight vector gaps #493

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Fix duplicate device-extension docs and Frames-in-flight vector gaps #493

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33 changes: 5 additions & 28 deletions en/03_Drawing_a_triangle/01_Presentation/01_Swap_chain.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -41,34 +41,11 @@ std::vector<const char*> requiredDeviceExtension = {

It should be noted that the availability of a presentation queue,
as we checked in the previous chapter, implies that the swap chain extension
must be supported. However, the extension does have to be explicitly enabled.

== Enabling device extensions

Using a swapchain requires enabling the `VK_KHR_swapchain` extension first.
Enabling the extension just requires a small change to the logical device
creation structure:

[,c++]
----
deviceCreateInfo.enabledExtensionCount = requiredDeviceExtension.size();
deviceCreateInfo.ppEnabledExtensionNames = requiredDeviceExtension.data();
----

Alternatively, we can do this at the construction and keep this very succinct:

[,c++]
----
std::vector requiredDeviceExtension = { vk::KHRSwapchainExtensionName };

float queuePriority = 0.5f;
vk::DeviceQueueCreateInfo deviceQueueCreateInfo{.queueFamilyIndex = queueIndex, .queueCount = 1, .pQueuePriorities = &queuePriority};
vk::DeviceCreateInfo deviceCreateInfo{.pNext = &featureChain.get<vk::PhysicalDeviceFeatures2>(),
.queueCreateInfoCount = 1,
.pQueueCreateInfos = &deviceQueueCreateInfo,
.enabledExtensionCount = static_cast<uint32_t>(requiredDeviceExtension.size()),
.ppEnabledExtensionNames = requiredDeviceExtension.data()};
----
must be supported. We already passed `requiredDeviceExtension` to
`vk::DeviceCreateInfo` when
xref:../00_Setup/04_Logical_device_and_queues.adoc[creating the logical device],
so the extension is enabled and there's no further device-creation code
needed here.

== Querying details of swap chain support

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17 changes: 16 additions & 1 deletion en/03_Drawing_a_triangle/03_Drawing/03_Frames_in_flight.adoc
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Expand Up @@ -28,7 +28,9 @@ Generally, extra latency isn't desired.
But giving the application control over the number of frames in flight is another example of Vulkan being explicit.

Each frame should have its own command buffer, set of semaphores, and fence.
Rename and then change them to be ``std::vector``s of the objects:
Rename and then change them to be ``std::vector``s of the objects. The single
fence, previously called `drawFence`, becomes `inFlightFences` here rather
than just gaining an `s`, since we now have one fence per frame in flight:

[,c++]
----
Expand Down Expand Up @@ -83,6 +85,19 @@ We will use a frame index for that purpose:
uint32_t frameIndex = 0;
----

`commandBuffer` is now a vector too, so `recordCommandBuffer` can no longer
use it directly - add a local reference to the buffer for the current frame
at the top of the function:

[,c++]
----
void recordCommandBuffer(uint32_t imageIndex)
{
auto &commandBuffer = commandBuffers[frameIndex];
...
}
----

The `drawFrame` function can now be modified to use the right objects:

[,c++]
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