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Use designated initializers and use explicit array types #212

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17 changes: 11 additions & 6 deletions en/06_Texture_mapping/02_Combined_image_sampler.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -20,12 +20,13 @@ We'll simply put it in the binding after the uniform buffer:

[,c++]
----
std::array bindings = {
std::array<vk::DescriptorSetLayoutBinding, 2> bindings = {
vk::DescriptorSetLayoutBinding( 0, vk::DescriptorType::eUniformBuffer, 1, vk::ShaderStageFlagBits::eVertex, nullptr),
vk::DescriptorSetLayoutBinding( 1, vk::DescriptorType::eCombinedImageSampler, 1, vk::ShaderStageFlagBits::eFragment, nullptr)
};
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@asuessenbach asuessenbach Oct 27, 2025

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You could as well go one step further with designated initializers, like

    std::array<vk::DescriptorSetLayoutBinding, 2> bindings = {
      { { .binding = 0, .descriptorType = vk::DescriptorType::eUniformBuffer, .descriptorCount = 1, .stageFlags = vk::ShaderStageFlagBits::eVertex },
        { .binding = 1, .descriptorType = vk::DescriptorType::eCombinedImageSampler, .descriptorCount = 1, .stageFlags = vk::ShaderStageFlagBits::eFragment } }
    };

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@SaschaWillems SaschaWillems Oct 27, 2025

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It's one of those areas where the tutorial is lacking consistency. We prob. should discuss this on our next call and agree on how we want to write code and then start updating the documentation accordingly.


vk::DescriptorSetLayoutCreateInfo layoutInfo({}, bindings.size(), bindings.data());
vk::DescriptorSetLayoutCreateInfo layoutInfo { .bindingCount = static_cast<uint32_t>(bindings.size()),
.pBindings = bindings.data() };
----

Make sure to set the `stageFlags` to indicate that we intend to use the combined image sampler descriptor in the fragment shader.
Expand All @@ -37,11 +38,15 @@ Go to the `createDescriptorPool` function and modify it to include a `VkDescript

[,c++]
----
std::array poolSize {
std::array<vk::DescriptorPoolSize, 2> poolSize {
vk::DescriptorPoolSize( vk::DescriptorType::eUniformBuffer, MAX_FRAMES_IN_FLIGHT),
vk::DescriptorPoolSize( vk::DescriptorType::eCombinedImageSampler, MAX_FRAMES_IN_FLIGHT)
};
vk::DescriptorPoolCreateInfo poolInfo(vk::DescriptorPoolCreateFlagBits::eFreeDescriptorSet, MAX_FRAMES_IN_FLIGHT, poolSize);

vk::DescriptorPoolCreateInfo poolInfo { .flags = vk::DescriptorPoolCreateFlagBits::eFreeDescriptorSet,
.maxSets = MAX_FRAMES_IN_FLIGHT,
.poolSizeCount = static_cast<uint32_t>(poolSize.size()),
.pPoolSizes = poolSize.data() };
----

Inadequate descriptor pools are a good example of a problem that the validation layers will not catch: As of Vulkan 1.1, `vkAllocateDescriptorSets` may fail with the error code `VK_ERROR_POOL_OUT_OF_MEMORY` if the pool is not sufficiently large, but the driver may also try to solve the problem internally.
Expand Down Expand Up @@ -70,9 +75,9 @@ This is where the objects from the previous chapter come together.

[,c++]
----
std::array descriptorWrites{
std::array<vk::WriteDescriptorSet, 2> descriptorWrites {
vk::WriteDescriptorSet( descriptorSets[i], 0, 0, 1, vk::DescriptorType::eUniformBuffer, nullptr, &bufferInfo ),
vk::WriteDescriptorSet( descriptorSets[i], 1, 0, 1, vk::DescriptorType::eCombinedImageSampler, &imageInfo)
vk::WriteDescriptorSet( descriptorSets[i], 1, 0, 1, vk::DescriptorType::eCombinedImageSampler, &imageInfo )
};
device.updateDescriptorSets(descriptorWrites, {});
----
Expand Down
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