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Learn about game development technology

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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
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Vulkan renderer updated with shadow maps

Shadow maps are now supported in the new Vulkan renderer, for point, spot, and box lights! Our new forward renderer eliminates all the problems that deferred renderers have with transparency, so shadows and lighting works great with transparent surfaces. Transparent objects even receive lighting from their back face automatically! There is some shadow acne, which I am not going to leave alone right now because I want to try some ideas to eliminate it completely, so you neve
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Vulkan Render Pipeline

Having completed a hard-coded rendering pipeline for one single shader, I am now working to create a more flexible system that can handle multiple material and shader definitions. If there's one way I can describe Vulkan, it's "take every single possible OpenGL setting, put it into a structure, and create an immutable cached object based on those settings that you can then use and reuse". This design is pretty rigid, but it's one of the reasons Vulkan is giving us an 80% performance increase ove
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Vulkan Progress

I was going to write about my thoughts on Vulkan, about what I like and don't like, what could be improved, and what ramifications this has for developers and the industry. But it doesn't matter what I think. This is the way things are going, and I have no say in that. I can only respond to these big industry-wide changes and make it work to my advantage. Overall, Vulkan does help us, in both a technical and business sense. That's as much as I feel like explaining. Beta subscribers ca
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Articles

Vulkan on Mac with MoltenVK

When it comes to complex projects I like to focus on whatever area of technology causes me the most uncertainty or worry. Start with the big problems, solve those, and as you continue development the work gets easier and easier. I decided at this stage I really wanted to see how well Vulkan graphics work on Mac computers. Vulkan doesn't run natively on Mac, but gets run through a translation library called MoltenVK. How well does MoltenVK actually work? There was only one way to find out...
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Vulkan on AMD Graphics Cards

I have procrastinated testing of our new 3D engine on AMD hardware for a while. I knew it was not working as-is, but I was not too concerned. One of the promises of Vulkan is better support across-the-board and fewer driver bugs, due to the more explicit nature of the API. So when I finally tried out the engine on an R9 200 series card, what would actually happen? Would the promise of Vulkan be realized, or would developers continue to be plagued by problems on different graphics cards? Read on
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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
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Articles

Vulkan Dynamic Rendering

The VK_KHR_dynamic_rendering extension has made its way into Vulkan 1.2.203 and I have implemented this in Ultra Engine. What does it do? Instead of creating renderpass objects ahead of time, dynamic rendering allows you to just specify the settings you need as your are performing filling in command buffers with rendering instructions. From the Khronos working group: In my experience, post-processing effects is where this hurt the most. The engine has a user-defined stack of post-pro
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Voxel Ray Tracing and Physically-Based Rendering

Light is made up of individual particles called photons. A photon is a discrete quantum of electromagnetic energy. Photons are special because they have properties of both a particle and a wave. Photons have mass and can interact with physical matter. The phenomenon of "solar pressure" is caused by photons bombarding a surface and exerting force. (This force actually has to be accounted for in orbital mechanics.) However, light also has a wavelength and frequency, similar to sound or other wave
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Voxel ray tracing and motion

So far the new Voxel ray tracing system I am working out is producing amazing results. I expect the end result will look like Minecraft RTX, but without the enormous performance penalty of RTX ray tracing. I spent the last several days getting the voxel update speed fast enough to handle dynamic reflections, but the more I dig into this the more complicated it becomes. Things like a door sliding open are fine, but small objects moving quickly can be a problem. The worst case scenario is whe
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Voxel Madness

After three days of intense work, I am proud to show you this amazing screenshot: What is so special about this image? I am now successfully uploading voxel data to the GPU and writing lighting into another texture, using a texture buffer object to store the voxel positions as unsigned char uvec3s. The gray color is the ambient light term coming from the Blinn-Phong shading used in the GI direct light calculation. The next step is to create a light grid for the clustered forward rende
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Voxel GI: Light Bounces

I implemented light bounces and can now run the GI routine as many times as I want. When I use 25 rays per voxel and run the GI routine three times, here is the result. (The dark area in the middle of the floor is actually correct. That area should be lit by the sky color, but I have not yet implemented that, so it appears darker.) It's sort of working but obviously these results aren't usable yet. Making matters more difficult is the fact that people love to show their best scr
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Voxel GI: GPU Acceleration, corrected bounces, and reflections

I've moved the GI calculation over to the GPU and our Vulkan renderer in Leadwerks Game Engine 5 beta now supports volume textures. After a lot of trial and error I believe I am closing in on our final techniques. Voxel GI always involves a degree of light leakage, but this can be mitigated by setting a range for the ambient GI. I also implemented a hard reflection which was pretty easy to do. It would not be much more difficult to store the triangles in a lookup table for each voxel in order to
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Voxel GI: Colors and Fast Downsampling

The polygon voxelization process for our voxel GI system now takes vertex, material, and base texture colors into account. The voxel algorithm does not yet support a second color channel for emission, but I am building the whole system with that in mind. When I visualize the results of the voxel building the images are pretty remarkable! Of course the goal is to use this data for fast global illumination calculations but maybe they could be used to make a whole new style of game graphics.
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Voxel Direct Lighting on the GPU

We left off on voxels when I realized the direct lighting needed to be performed on the GPU. So I had to go and implement a new clustered forward renderer before I could do anything else. Well, I did that and now I finally have voxel lighting calculation being performed with the same code that renders lighting. This gives us the data we need to perform cone step tracing for real-time dynamic global illumination. The shadows you see here are calculated using the scene shadowmaps, not b
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Voxel Cone Tracing Part 5 - Hardware Acceleration

I was having trouble with cone tracing and decided to first try a basic GI algorithm based on a pattern of raycasts. Here is the result: You can see this is pretty noisy, even with 25 raycasts per voxel. Cone tracing uses an average sample, which eliminates the noise problem, but it does introduce more inaccuracy into the lighting. Next I wanted to try a more complex scene and get an estimate of performance. You may recognize the voxelized scene below as the "Sponza" scene freque
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Voxel Cone Tracing Part 4 - Direct Lighting

Now that we can voxelize models, enter them into a scene voxel tree structure, and perform raycasts we can finally start calculating direct lighting. I implemented support for directional and point lights, and I will come back and add spotlights later. Here we see a shadow cast from a single directional light: And here are two point lights, one red and one green. Notice the distance falloff creates a color gradient across the floor: The idea here is to first calculate direc
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Voxel Cone Tracing Part 3 - Raycasting

I added a raycast function to the voxel tree class and now I can perform raycasts between any two positions. This is perfect for calculating direct lighting. Shadows are calculated by performing a raycast between the voxel position and the light position, as shown in the screenshot below. Fortunately the algorithm seems to work great an there are no gaps or cracks in the shadow: Here is the same scene using a voxel size of 10 centimeters: If we move the light a little lower
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Voxel Cone Tracing Part 2 - Sparse Octree

At this point I have successfully created a sparse octree class and can insert voxelized meshes into it. An octree is a way of subdividing space into eight blocks at each level of the tree: A sparse octree doesn't create the subnodes until they are used. For voxel data, this can save a lot of memory. It was difficult to get the rounding and all the math completely perfect (and it has to be completely perfect!) but now I have a nice voxel tree that can follow the camera around and
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Voxel Cone Tracing

I've begun working on an implementation of voxel cone tracing for global illumination. This technique could potentially offer a way to perfrorm real-time indirect lighting on the entire scene, as well as real-time reflections that don't depend on having the reflected surface onscreen, as screen-space reflection does. I plan to perform the GI calculations all on a background CPU thread, compress the resulting textures using DXTC, and upload them to the GPU as they are completed. This means t
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Articles

Voxel Cone Step Tracing Refinement

Before proceeding with multiple GI volumes, I decided to focus on just getting the lighting to look as close to perfect as possible, with a single stage. Injecting the ambient light into the voxel data made flat-lit areas appear much more "3D", with color bleeding and subtle contours everywhere. Lighting only: Lighting + albedo Some adjustments to the way the sky color is sampled gave a more lifelike appearance to outdoor lighting. Before: After. N
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Josh in Articles

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Voxel Cone Step Tracing - Follow the Camera

Until now, all my experiments with voxel cone step tracing placed the center of the GI data at the world origin (0,0,0). In reality, we want the GI volume to follow the camera around so we can see the effect everywhere, with more detail up close. I feel my productivity has not been very good lately, but I am not being too hard on myself because this is very difficult stuff. The double-blind nature of it (rendering the voxel data and then using that data to render an effect) makes development ver
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Josh in Articles

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Voxel Cone Step Tracing - Emission and Motion

Adding emission into the cascaded voxel cone step tracing global illumination and dynamic reflections system (SEO ftw) was simple enough: There's some slight trailing but it looks okay to me. There is a bit of a "glitch" in that when the emissive surface gets near the wall, the ambient occlusion kicks in, even though the sphere is self-illuminating. This happens because the emission color is mixed with the light voxel during the rasterization step. I could fix this by storing emis
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Josh in Articles

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Voxel Cone Step Tracing - Cascaded Volumes

I had to spend several weeks just eliminating light leaks and other artifacts, and getting the results I wanted in a variety of scenes. The results are looking good. Everyone who tries implementing this technique has problems with light leaks but I have fortunately been able to avoid this with careful planning: Now that I have nice results with a single volume texture centered at the origin, it's time to add additional stages. The idea is to have a cascading series of volume textures
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Visual Studio 2017: Not Ready

A release candidate for Visual Studio 2017 was released in November. I took a chance that the final release would be out in December, but it isn't here yet. Releasing Leadwerks 4.2 built with VC 2017 could possibly cause the program to not run on some computers, because the Visual Studio 2017 redistributable is not out yet, and there is no option yet to make this part of the installation on Steam.   Because of this, I am going to release Leadwerks 4.2 for use with Visual Studio 2015, and upg
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