pyromuffin

Hi, Today I will talk about a quick (slow) hack for getting some platform specific code working crossplatform. This is really about correctness, and not speed - I mean, otherwise the shader code wouldn't run on windows anyway. This hack won't be necessary once we can switch over to DXC - Microsoft's new shader compiler with shader model 6.0, but for now, that's out of reach. from GPUopen... though I'm pretty sure this isn't actually what it does. In order to explain what the function Ballot() actually does, I need to first take a little diversion to explain GPU hardware. GPU SIMDs The way a (modern, discrete) GPU works is that it executes instructions WAVE_SIZE (64 on AMD and 32 on Nvidia) at a time, all in lockstep. An easy way to think about it is that a set of WAVE_SIZE threads all share one instruction pointer. A group of WAVE_SIZE threads all located on a single SIMD is called a wave (or warp, using NV terminology). The cool thing about...

Hello, Today's galaxy brain idea is to use integer math to do arbitrary rotation about a point. Why? I can already hear you saying "We have very nice floating point units that are good at this already!" and I say, No thanks  to the floating point unit. They're all well and good, but converting between floats and ints is slow on the GPU, wasting a whole instruction and especially so when you want to do index calculations. Also consider that on newer versions of GCN, we have packed ops, but no packed float/int conversions. Also, also consider that GCN doesn't have scalar floating point ops, and if you want to do float math in a scalar context, you'll be issuing vector instructions with SGPR sources! If you are maxed out on VALU and want to offload some calculations to SALU, then you're only making your problem worse if you need to do floating point ops.  Think about the index rotation case: read in some integer index data, maybe a thread...

Hi, Today's post is about how to do nothing in HDR. That's just a clickbait way of saying I want to transform an SDR/SRGB gamma encoded (hereafter referred to as just SDR) image such that it appears like an SDR image after PQ encoding. The buffer you'll retreive from an SDR swapchain on windows is precisely that: an SDR/SRGB gamma encoded texture. Essentially, I want to press the button that turns on HDR and see nothing  happen. This is useful because maybe you want to toggle or lerp between SDR/HDR, so that you can compare the two. In the HDR Injector , I need to do this because once I've created the HDR swapchain, windows doesn't want to go back to the SDR swapchain for some reason . Also, I need to be able to sample parts of the SDR backbuffer to determine which parts had UI on them, or if color grading/tonemapping/post-processing occurred. Why is this even a problem? As I mentioned in my previous posts, HDR images are encoded in a different way tha...

Hey! If you missed it, yesterday I wrote an artisanal blogue poaste about a tool I am working on called the HDR injector . Today, I will write about how to present an HDR image in Windows. Some of this will be a summary of the talk by Evan Hart at GDC 2018. There are three steps, which I don't think are explained anywhere, except maybe within these ultra-rare DX12 samples that I had to catch midair from a hot tweet. Set your swapchain effect to DXGI_SWAP_EFFECT_FLIP_DISCARD . Emphasis on FLIP. The GDC talk above seems to think this isn't 100% required, but I couldn't get any HDR working without it. Set your swapchain buffer format to an HDR compatible backbuffer format. The ones that work for me are:  DXGI_FORMAT_R16G16B16A16_FLOAT and  DXGI_FORMAT_R10G10B10A2_UNORM , though I expect other formats might work. I haven't tested all of them. Depending on which format you picked in ( 2 ) you need to select the correct color space. If you  selected RGB...

Hi, friends. It's been about 3 years since my last blog post. A few things have happened in the mean time. I currently live in the SF bay (deep under the sea, biding my time) and work for Sony, doing PS4 graphics support. Cool. I'm not really going to talk about that today - just a quick catch up for those of you playing along at home. I will talk about a little project I've been working on in my free time.  HDR basics Fast forward. We currently live in the year 2018: a time of incredible power. The planet glows with unnatural energies and we're able to channel these Occult Phenomena directly into our eyes via Highe Dynamick Range televison and monitor devices. The advantage of these devices is twofold: Enhanced brightness - things can be brighter, and show a more realistic range of brights/darks Wide color - you can show a wider range of colors. This is hard to describe if you haven't already seen it. It's astounding how good it can look. ...