PowerVR GR6500: Ray tracing is the future and the future is now (opens in new tab)

That's really great. Did you use emscripten or is the renderer programmed in Javascript?

I'm sorry man, but that sounds crazy. Raytraced scenes are much easier for artists to control the results because things actually behave like you would intuitively expect (if the amount of rays is high enough).

If raytraced scenes were hard to control, why would every single animated movie be raytraced?

Raytracing really is the be all and end all of graphics. The more rays you can render, the more realistic your scene will be, up to 100% realism.

Of course, we can come pretty far with the hacks as well, and it's hard to say if hardware raytracing can come close to the quality hardware shader hacks can achieve on traditional GPU's in real time.

You might feel differently if you ever had to do shadow mapping on traditional hardware. Even in AAA games, there are tons of artifacts in the shadows. Same goes for reflections.

I don't see why it's harder for artists to control the results... can you elaborate? It seems like it's going to be 90% the same. You have a point on a surface, you have a camera vector and light vectors, you supply a small piece of code and out pops a color. The major differences in the pipeline are in the scaffolding: depth tests, reflections, and shadows will be done in different ways. The differences for artists are that they'll have to learn a system with different limitations.

My guess is that game graphics are going to follow the developments in movie CGI. Pixar switched to ray tracing in 2013, and games will switch when hardware powers up and expertise filters down.

I'm sorry but there is a pronounced industry trend exactly against what you argue. Physically based rendering is winning out almost everywhere. A straightforward path tracer is capable of simulating nearly all the physics of light to any desired degree of fidelity. Part of why it's won out is that it's actually far simpler for artists to work in terms of real world material concepts vs tuning abstract parameters in fake models that can be coerced into to looking real. Eg "dusty metal with this albedo map" vs maps for parameters in some mutilated and extended phong shader.

I don't think so, not with modern tools anyway. Raytracing is in my experience the technology that most closely models the real world. Most technologies used in games even today are hacks, using precomputed values oftentimes derived from ray traced models. Raytracing is quite natural to work with because it simulates real world objects and does so in a realistic manner. The only difficulty might be caused by the lack of such real-time raytracing hardware as depicted here causing slower development as one has to wait for a scene or animation to render. IMO, raytracing is indeed the pinnacle of photorealistic rendering currently.

I've yet to see a single rasterised game come anywhere close to ray-tracing in the shadow department and that's what destroys immersion for me the most: low-resolution, aliased shadows crawling all over the place.

Ray tracing works backwards from the way actual optics works. It sends out a ray for each pixel and then finds out what it falls on then does math to figure out what it should look like. In a simple example, you have a few light sources and you trace a ray back to an object (polygonal surface), then you shoot off other rays from there toward the light sources (or you shoot off potential reverse reflection rays). If something is blocking a light source you adjust the amount of shadow being rendered or you bounce off of that surface again toward the light sources, and so on. Making it possible to render shadows, reflections, and so on with decent fidelity.

In contrast to that technique you have "radiosity", where the illumination at each point on a surface is calculated based on its environment. Radiosity is better at rendering diffuse light, ray tracing is better at rendering reflected light.

The underlying difficulty is that illumination is a maddeningly combinatorial problem. In principle every part of every object in a scene contributes illumation to every part of every other object. The light falling on a desk lamp from the LEDs of a clock also illuminates the desk itself, and so on. Radiosity and ray tracing attempt to solve those problems by making simplifying assumptions and performing a subset of the calculations necessary to illuminate and render a scene completely faithfully. In principle a more proper ray tracing algorithm would be to send out a huge number of rays in every direction for every image field ray, then follow each of those through their evolution, sending out yet more for surfaces each fall on, and so on. But that's far too computationally intensive (it's an O(n!) level problem).

Path tracing is similar to these techniques but makes different simplifying assumptions. And the most important aspect is that instead of deterministically calculating everything in a specific way it uses a monte-carlo method of statistically sampling different "paths" then using the data to estimate the resulting illumination/image rendering. Path tracing results in a compromise between ray tracing and radiosity of being able to render both reflective and diffuse light well, though it has its own short-comings.

They should have showed the car moving. You'd have seen the reflection slide up the hood in the raytraced demo.

It takes A LOT of work and planning to get light and shadow correct in a raster setting. Most AAA games don't bother. Raytracing makes it easy to get them right, which will make all the difference in the world.

I don't think it _is_ super obvious. Rather, I think the goal is to properly fill in the scene with the very subtle clues we unconsciously look for.

I had a similar experience working a bit with Radiance years ago. The output looked mediocre, at best, but it was reporting a real view of the scene; it's call to fame is that it outputs real energy values in physical units (like energy per unit solid angle or luminance or such). But despite the cartoony models I provided, it did demonstrate subtleties that weren't hacks (needed for this application), things that you wouldn't think to or bother implementing directly.

This? This grabs a lot of needed visual artifacts faster and more correctly without crazy hacks (or so it seems - it does say hybrid rendering).

I think that's because they used poor art assets. Most games look far more pleasing and realistic than those examples while using traditional rasterization pipelines, mostly on the strength of the artists and an offline prebaking stage.

There's a reason Nvidia employs top CG talent for their hardware demos. A pretty demo sells more than an ugly one, even if they essentially pull off the same effect.

Mobile. They can do that on mobile. :)

The water does.

Thanks I completely forgot about that one. :)

I see headlines like this and I'm like "are they still in the driver dark ages? Yep? Call me when they stop acting like a 2 year old and play ball in Mesa"

Oh, the memories ...

Before it was renamed "povray", it was called "dkbtrace". I printed the entire dkbtrace source and studied it, to see how a real Ray Tracer worked; and through it, I learned how efficient vtbls work (it was 1990 C, and though C++ was already starting to become visible and popular, it was still "that new language that may or may not become popular" - dkbtrace implemented all the OO inside).

Thanks, D.K.B.

> I'd wager that the current rasterising pipeline is more flexible than one based on raytracing - capable of generating a range of styles, not just photorealistic ones

Nope. I'd say the "raytracing pipeline" really does replace only the rasterization step, and once the triangle to draw is "found", you do whatever shading/lighting/fx/fragshader you want to draw it with? Wouldn't this be the most sensible approach?

Rasterization in lay-man's terms really is just "figure out which triangle, if any, is 'hit' at this pixel", so a historically much faster and very neat hack to avoid the tracing of a ray..

But you don't get cheap soft-shadowing / ambient occlusion / reflect-refract and you'd need to do occlusion culling seperately for current-gen "complex" scenes to avoid a drawcall for all kinds of hidden objects. That's where at some point raytracing as it becomes more feasible also becomes much more attractive. Potentially also reducing geometry-LODing headaches etc..

> Also, how long before cryptocurrency miners use these to gain step function over current gpus.

I can't imagine these ever being cheaper than ASICs.

> Also, how long before cryptocurrency miners use these to gain step function over current gpus.

Ugh. Never. Computing a hash won't be any faster on these GPUs.

I think you're thinking of raycasting.

It was an example of ray casting and not ray tracing.

Wouldn't ray tracing make content production easier, needing fewer tricks to fake behaviour of light and shadow?

They'd have to either sacrifice yield or sacrifice FP32 units.

Also, if they put FP64 support in their gaming cards they wouldn't be able to charge scientists and engineers extra.

Who is going to use FP64 in iPads and Android tablets?

hmm, looks better now on desktop than on phone