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Memory Management in Vulkan

Memory Management in Vulkan

Vulkan gives us explicit control over the way data is handled in system and video memory. You can map a buffer into system memory, modify it, and then unmap it (giving it back to the GPU) but it is very slow to have a buffer that both the GPU and CPU can access. Instead, you can create a staging buffer that only the CPU can access, then use that to copy data into another buffer that can only be read by the GPU. Because the GPU buffer may be in-use at the time you want to copy data to it, it is b

Josh

Josh

Buffers in Vulkan

Buffers in Vulkan

I've now got the Vulkan renderer drawing multiple different models in one single pass. This is done by merging all mesh geometry into one single vertex and indice buffer and using indirect drawing. I implemented this originally in OpenGL and was able to translate the technique over to Vulkan. This can allow an entire scene to be drawn in just one or a few draw calls. This will make a tremendous improvement in performance in complex scenes like The Zone. In that scene in Leadwerks the slow step i

Josh

Josh

First Vulkan Performance Results

Using my box test of over 100,000 boxes, I can compare performance in the new engine using OpenGL and Vulkan side by side. The results are astounding. Our new engine uses extensive multithreading to perform culling and rendering on separate threads, bringing down the time the GPU sits around waiting for the CPU to nearly zero. Hardware: Nvidia GEForce GTX 1070 (notebook) OpenGL: ~380 FPS Vulkan 700+ FPS. FRAPS does not work with Vulkan, so the only FPS counter I have is

Josh

Josh

Uniform Buffers in Vulkan

Uniform Buffers in Vulkan

Following this tutorial, I have managed to add uniform buffers into my Vulkan graphics pipeline. Since each image in the swapchain has a different graphics pipeline object, and uniform buffers are tied to a pipeline, you end up uploading all the data three times every time it changes. OpenGL might be doing something like this under the hood, but I am not sure this is a good approach. There are three ways to get data to a shader in Vulkan. Push constants are synonymous with GLSL uniforms, althoug

Josh

Josh

Command Buffer Synchronization in Vulkan

Command Buffer Synchronization in Vulkan

The Vulkan graphics API is unbelievably complex. To create a render context, you must create a series of images for the front and back buffers (you can create three for triple-buffering). This is called a swap chain. Now, Vulkan operates on the principle of command buffers, which are a list of commands that get sent to the GPU. Guess what? The target image is part of the command buffer! So for each image in your swap chain, you need to maintain a separate command buffer  If anything changes in y

Josh

Josh

Vulkan Shader Compilation

One of the best points of Vulkan is how shaders are loaded from precompiled Spir-V files. This means GLSL shaders either work or they don't. Unlike OpenGL, there is no different outcome on Intel, AMD, or nVidia hardware. SPIR-V files can be compiled using a couple of different utilities. I favor LunarG's compiler because it supports #include directives. Shader.vert: #version 450 #extension GL_ARB_separate_shader_objects : enable #include "VertexLayout.glsl" layout(push_constant) unifo

Josh

Josh

Vulkan Shader Uniforms

In Vulkan all shader uniforms are packed into a single structure declared in a GLSL shader like this: layout(push_constant) uniform pushBlock { vec4 color; } pushConstantsBlock; You can add more values, but the shaders all need to use the same structure, and it needs to be declared exactly the same inside the program. Like everything else in Vulkan, shaders are set inside a command buffer. But these shader values are likely to be constantly changing each frame, so how do you hand

Josh

Josh

Vulkan Nitty-Gritty

I am surprised at how quickly Vulkan development is coming together. The API is ridiculously verbose, but at the same time it eliminates a lot of hidden states and implicit behavior that made OpenGL difficult to work with. I have vertex buffers working now. Vertices in the new engine will always use this layout:     struct VkVertex     {         float position[3];         float normal[3];         float texcoords0[2];         float texcoords1[2];         float tangent[3];         unsigned cha

Josh

Josh

Resizable Vulkan Window

When a window in Vulkan resizes you have to manually delete the about a dozen objects and then recreate them with the new size. It's unbelievably complicated. They've pushed all the driver complexity onto the application, in an effort to simplify the job of writing drivers. I can see the advantage to this, because OpenGL drivers in the past were always inconsistent, but it is still shocking how many little details they expose in Vulkan. Just resizing a window and swapping the screen buffer invol

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Josh

Hello Vulkan

Hello Vulkan

Two days and 823 lines of code later, I present to you the Vulkan triangle of awesomeness, running in our engine: Here are my thoughts on Vulkan: It's ridiculously verbose. You have to specify every little detail of the rasterizer, there's a million classes to create, and every little variable has to be exactly right. There's really no reason for this because 90% of the code is just something you copy and paste. Shaders can use GLSL, which seems very weird, but it makes thin

Josh

Josh

Getting Started with Vulkan

Getting Started with Vulkan

The latest design of my OpenGL renderer using bindless textures has some problems, and although these can be resolved, I think I have hit the limit on how useful an initial OpenGL implementation will be for the new engine. I decided it was time to dive into the Vulkan API. This is sort of scary, because I feel like it sets me back quite a lot, but at the same time the work I do with this will carry forward much better. A Vulkan-based renderer can run on Windows, Linux, Mac, iOS, Android, PS4, an

Josh

Josh

Turbo Game Engine Design Document

Subscribers can now download my current revision of the Turbo Game Engine design document in the private forum here: Here are a few excerpts: The document is still evolving so expect changes and updates.

Josh

Josh

Dev Log

My last NASA project is complete. There's a physics bug in Leadwerks 4.6 that will get resolved this weekend. Starting Monday I am going to focus on the new engine again and move us forward so we can release in 2020. I am really looking forward to getting back in the game.

Josh

Josh

New game engine examples

The new game engine needs to roll out with some top-notch examples showing off what it can do. Here's what I want: First-person shooter Offroad racing game Space shoot-em-up side-scroller. Side-scoller platformer similar to the Contra Playstation game. Now what I can use your help with is finding good example games on YouTube or Steam that I can start designing these samples around. Post your ideas below!

Josh

Josh

Smart Pointers Lesson

This is something I typed up for some colleagues and I thought it might be useful info for C++ programmers. To create an object: shared_ptr<TypeID> type = make_shared<TypeID>(constructor args…) This is pretty verbose, so I always do this: auto type = make_shared<TypeID>(constructor args…) When all references to the shared pointer are gone, the object is instantly deleted. There’s no garbage collection pauses, and deletion is always instant: auto thing = m

Josh

Josh

Leadwerks Game Engine 4.6 Release Candidate

An update is available on the beta branch on Steam with a few bug fixes. I'm going to release 4.6 with the current features because a lot of bugs have been fixed since 4.5 and we're overdue for an official release. 4.7 will add a new vehicle system, character crouching physics, and some other things, and will be out later this year.

Josh

Josh

GDC 2019

I have not gone in several years because everything we were doing revolved around Steam, and it just didn't seem very important. But this year I had some business to attend to so I spent the last three days in San Francisco. I still have a lot of friends in the game industry, and the reaction to my plans for the new engine was very positive. A few years ago people would have groaned at the idea of another engine, but it seems they are now bored with technology and very open to something new

Josh

Josh

Leadwerks Game Engine 4.6 Beta Update

A new update is available on the beta branch on Steam. This adds numerous bug fixes. The Linux build of the editor is compiled with Ubuntu 16.04 and the engine libraries and executables are compiled with Ubuntu 18.04. Linux users, please let me know how this works for you.

Josh

Josh

Wrapping up at NASA

I'm in DC this week helping the folks at NASA wrap up some projects. I'm going to move back to a supportive role and focus on development of Leadwerks 4.6 and the new engine, and I am helping them to hire some programmers to replace me. We found some very talented people who I am confident will do a fantastic job, and I can't wait to see what they create using Leadwerks Game Engine. I helped a team using Leadwerks at NASA get through some big milestones and expand. I hope that someday soon

Josh

Josh

Real Bindless Textures

Previously I talked about array textures acting as "bindless" textures, but there is an actual OpenGL extension that allows a shader to access any texture without the stupid texture binding / slot convention that limits OpenGL 4.0 shaders to a minimum of 16 textures. Implemenation was surprisingly easy, although Mac hardware apparently does not support this extension. When combined with the multi-draw commands in OpenGL 4.3, and some other tricks, it is possible to render multiple sets of object

Josh

Josh

Bindless Textures

Bindless Textures

The clustered forward renderer in Leadwerks 5 / Turbo Game Engine required me to implement a texture array to store all shadow maps in. Since all shadow maps are packed into a single 3D texture, the shader can access all required textures outside of the number of available texture units, which only gives 16 guaranteed slots. I realized I could use this same technique to pack all scene textures into a few arrays and completely eliminate the overhead of binding different textures. In order to

Josh

Josh

Fun with Stateless API

Leadwerks 5 / Turbo makes extensive use of multithreading. Consequently, the API is stateless and more explicit. There is no such thing as a "current" world or context. Instead, you explicitly pass these variables to the appropriate commands. One interesting aspect of this design is code like that below works perfectly fine. See if you can work through it and understand what's going on: int main(int argc, const char *argv[]) { //Create a model ;) auto box = CreateBox(nullptr); //Cre

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Josh

Loading Binary and Embedded GLTF files

Loading Binary and Embedded GLTF files

It turns out GLTF is actually three different file formats. 😫 Textures can be loaded from external files, embedded in a binary .glb file, but they can also be saved in an ASCII GLTF files using base64 encoding. Having three different ways to store textures is not a good design decision, but at least it's better than the disaster called Collada. (Note to Khronos: If your file format specification has more pages than a Tom Clancy novel it probably sucks.) Our GLTF loader now supports files wi

Josh

Josh

Development Days

Development Days

Some of the Leadwerks Game Engine design was originally developed to run on PC and mobile. In order to supported multiple renderers (OpenGL and OpenGLES) I implemented a system that uses an abstract base class with an API-specific class derived from that: Texture OpenGLTexture All OpenGL code was contained in the OpenGLTexture class. This worked fine, and theoretically it would have allowed us to support multiple renderers within one build, like OpenGL and Direc

Josh

Josh

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