Vulkan examples and demos

Future place for examples and demos for Khronos' new 3D and compute API Vulkan(tm)

Vulkan from my point-of-view

I recently did a write-up with my personal view on Vulkan for a hobby developer. It goes into detail on some of the most important things to consider when deciding on how to switch over from Vulkan and also clears up some things that several press articles got wrong.

Vulkan example base class

All examples are derived from a base class that encapsulates common used Vulkan functionality and all the setup stuff that's not necessary to repeat for each example. It also contains functions to load shaders and an easy wrapper to enable debugging via the validation layers.

If you want to create an example based on this base class, simply derive :

#include "vulkanexamplebase.h"
...
class MyVulkanExample : public VulkanExampleBase
{
  ...
  VulkanExample()
  {
    width = 1024;
    height = 1024;
    zoom = -15;
    rotation = glm::vec3(-45.0, 22.5, 0.0);
    title = "My new Vulkan Example";
  }
}

Validation layers

The example base class offers a constructor overload for enabling a default set of Vulkan validation layers (for debugging purposes). If you want to use this functionality, simple use the construtor override :

VulkanExample() : VulkanExampleBase(true)
{
  ...
}

todo : Document helper classes like vulkandebug

Examples

todo : In progress

Triangle

Most basic example. Renders a colored triangle using an indexed vertex buffer, only one pipeline with very simple shaders. Uses a single uniform buffer for the matrices.

Texture

Loads a single texture and displays it on a simple quad.

Pipelines

Pipelines replace the huge (and cumbersome) state machine of OpenGL. This example creates different pipelines with different states and shader setups.

Gears

Vulkan interpretation of glxgears. Procedurally generates separate meshes for each gear, with every mesh having it's own uniform buffer object for animation. Also demonstrates how to use different descriptor sets.

Mesh rendering

Uses assimp to load and a mesh from a common 3D format. The mesh data is then converted to a fixed vertex layout matching a basic set of shaders.

Mesh instancing

Renders hundreds of meshes using instances with uniforms for e.g. coloring each mesh separately.

Offscreen rendering

Uses a separate framebuffer (that is not part of the swap chain) for rendering a 3D scene off screen and blits it into a texture target displayed on a quad. The blit does scaling and (if required) also format conversions.

Radial blur

Demonstrates basic usage of fullscreen shader effects. The scene is rendered offscreen first, gets blitted to a texture target and for the final draw this texture is blended on top of the 3D scene with a radial blur shader applied.

Bloom

Implements a bloom effect to simulate glowing parts of a 3D mesh. A two pass gaussian blur (horizontal and then vertical) is used to generate a blurred low res version of the scene only containing the glowing parts of th the 3D mesh. This then gets blended onto the scene to add the blur effect.

Spherical environment mapping

Uses a matcap texture (spherical reflection map) to fake complex lighting. It's based on this article.

Parallax mapping

Like normal mapping, parallax mapping simulates geometry on a flat surface. In addition to normal mapping a heightmap is used to offset texture coordinates depending on the viewing angle giving the illusion of added depth.

(Tessellation shader) PN-Triangles

Generating curved PN-Triangles on the GPU using tessellation shaders to add details to low-polygon meshes, based on this paper.

(Tessellation shader) Displacement mapping

Uses tessellation shaders to generate and displace geometry based on a displacement map (heightmap).

(Geometry shader) Normal debugging

Renders the vertex normals of a complex mesh with the use of a geometry shader. The mesh is rendered solid first and the a geometry shader that generates lines from the face normals is used in the second pass.

Vulkan demo scene

More of a playground than an actual example. Renders multiple meshes with different shaders (and pipelines) including a background.

Building

todo : In progress The repository contains CMake files for all demos and all required headers to compile the example, so any platform that supports CMake and has a C++11 compatible compiler should work.

Dependencies

Note: Included in the repository

• OpenGL Mathematics (GLM)
• OpenGL Image (GLI)
• Open Asset Import Library
• Vulkan Headers (not yet available)

External resources

TODO : In progress

• Official list of Vulkan resources