Rendering

VulkanRender creates a graphics pipeline for either a traditional VulkanRenderPass or VulkanDynamicRendering.

Define a renderer

A renderer subclass provides:

• vertex and fragment SPIR-V through LoadVertexShader() and LoadFragmentShader();

• vertex buffer and attribute descriptions;

• descriptor bindings through GetBindingInfo().

It may also override culling, front-face orientation, depth testing, depth writing, and color blending.

class TriangleRenderer : public core::vulkan::VulkanRender {
 public:
  TriangleRenderer(core::vulkan::VulkanContext* context,
                   const core::vulkan::DynamicRenderingInfo& info)
      : VulkanRender(context, info) {}

  void Draw(VkCommandBuffer command_buffer, VkExtent2D extent) {
    vkCmdBindPipeline(command_buffer,
                      VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);

    VkViewport viewport{};
    viewport.width = static_cast<float>(extent.width);
    viewport.height = static_cast<float>(extent.height);
    viewport.maxDepth = 1.0f;
    vkCmdSetViewport(command_buffer, 0, 1, &viewport);

    VkRect2D scissor{{0, 0}, extent};
    vkCmdSetScissor(command_buffer, 0, 1, &scissor);
    vkCmdDraw(command_buffer, 3, 1, 0, 0);
  }

 protected:
  const std::vector<uint32_t> LoadVertexShader() const override;
  const std::vector<uint32_t> LoadFragmentShader() const override;
  std::vector<VkVertexInputBindingDescription>
  GetVertexBindingDescriptions() const override { return {}; }
  std::vector<VkVertexInputAttributeDescription>
  GetVertexAttributeDescriptions() const override { return {}; }
  std::vector<core::vulkan::BindingInfo>
  GetBindingInfo() const override { return {}; }
};

Dynamic rendering

The current triangle example uses DynamicRenderingInfo to declare its color format, then brackets draw commands with BeginDynamicRendering() and EndDynamicRendering().

core::vulkan::DynamicRenderingInfo pipeline_info{};
pipeline_info.color_formats = {swap_chain.swapchain_image_format};

TriangleRenderer renderer(&context, pipeline_info);
renderer.Init();

core::vulkan::VulkanDynamicRendering dynamic_rendering(&context);
const VkClearValue clear = {{{0.02f, 0.02f, 0.03f, 1.0f}}};

dynamic_rendering.BeginDynamicRendering(
    command_buffer.buffer(),
    swap_chain.swapchain_image_views[image_index],
    swap_chain.swapchain_extent, clear);
renderer.Draw(command_buffer.buffer(), swap_chain.swapchain_extent);
dynamic_rendering.EndDynamicRendering(command_buffer.buffer());

Warning

The formats supplied in DynamicRenderingInfo are baked into the graphics pipeline and must match the image views used when rendering. When depth or MSAA is enabled, pass matching depth, stencil, resolve, and sample-count information.

Traditional render passes

VulkanRenderPass creates color and optional depth attachments. Pass it to the corresponding VulkanRender constructor and use swapchain framebuffers when an application needs the render-pass model.

Record a draw

Inside the renderer’s draw method, bind the graphics pipeline, viewport, scissor, vertex and index buffers, and descriptor set before issuing vkCmdDraw*.

The base renderer uses dynamic viewport and scissor state. Set both during command recording before drawing. The triangle example also flips the projection matrix’s Y axis because Vulkan’s framebuffer coordinate convention differs from GLM’s default projection.