simple_polygons

Simple Polygons

This project demonstrates a basic raster rendering example in Vulkan, featuring:

• Camera manipulation
• Various geometric primitives
• Instance rendering
• Basic lighting model

Overview

The Simple Polygons sample showcases fundamental 3D graphics concepts using a modern Vulkan implementation. It serves as an educational tool for understanding basic rendering pipelines and scene management.

Descriptor Heap on a Classic Pipeline

This sample is the repository's reference for VK_EXT_descriptor_heap used with a traditional graphics VkPipeline — no shader objects. The per-frame camera UBO is reached through a bound descriptor heap (nvvk::DescriptorHeap) instead of a descriptor set. Everything else about the pipeline is conventional, so this is a minimal "heaps without abandoning pipelines" example — the counterpart most PSO-based engines actually want.

Key points, visible in createPipeline() and onRender():

• The pipeline opts into the heap with VK_PIPELINE_CREATE_2_DESCRIPTOR_HEAP_BIT_EXT (the pipeline-path counterpart of the shader-object flag VK_SHADER_CREATE_DESCRIPTOR_HEAP_BIT_EXT).
• A descriptor-heap pipeline has no VkPipelineLayout: the spec requires layout == VK_NULL_HANDLE (VUID-VkGraphicsPipelineCreateInfo-flags-11311). Because there is no layout, per-draw data is sent with vkCmdPushDataEXT, not vkCmdPushConstants.
• m_heap.cmdBindHeaps(...) replaces vkCmdBindDescriptorSets; vkCmdBindPipeline and the rest of the raster setup are unchanged.
• Only VK_EXT_descriptor_heap and VK_KHR_shader_untyped_pointers are enabled — deliberately no VK_EXT_shader_object.

For the descriptor-heap concept in depth (mapping modes, sampler/resource heaps), see the descriptor_heap sample. For the same idea on a ray-tracing pipeline, see ray_trace.

Key Components

Scene Initialization (onAttach)

The onAttach function sets up the rendering environment:

1. Initializes the VMA (Vulkan Memory Allocator) for efficient memory management
2. Constructs the scene graph, including:
   • Primitive geometries
   • Material definitions
   • Instance references to meshes
3. Creates Vulkan representations of the scene:
   • Generates vertex and index buffers via createVkBuffers
   • Establishes the rendering pipeline

User Interface (onUIRender)

The UI component provides:

• A camera widget in the settings window for view manipulation
• A viewport window displaying the rendered G-Buffer

Rendering Loop (onRender)

The main rendering function iterates through all instance nodes in the scene, drawing each element.

Note: For performance optimization, especially with larger scenes, consider recording a command buffer instead of looping over rendering nodes in real-time.