The changes introduced with update 1.40 for American Truck Simulator and Euro Truck Simulator 2 have been visible to the public for quite some time now, in the currently running open beta versions. By far the most visible change is the new lighting system, which turned out to be the biggest graphic overhaul since the release of these 2 titles. In one blog post, the developers come to talk to us about what is really going on “under the hood”. We translate all this for you (and we cut a little long passages):
And there was light !
SCS Software: “Our 3D engine's approach to representing light and color in scenes - and in the render buffers that end up being displayed on screen - was established over a decade ago. It was a time when the state of the art was to represent all RGB values in the numeric range 0-255, to fit into one byte of information. This is how all the values were defined, whether in a texel of a texture map (the "skin" of a 3D object, a tree, a vehicle or a skybox), or in the encoding of the intensity of a light source (from the tail lights of a vehicle to streetlights, to the intensity of the sun), and combining all of this in the rendering step into one pixel; this was again the representation in the display buffer to be displayed on the screen, with only 256 shades of each base color. "
“In recent years, the explosion of memory available in 3D cards, increases in computing power and the flexibility of shading languages for programming 3D card operations have paved the way for the storage and calculation of values. color and light with much higher precision and range. - with floating point numbers. In the real world, the difference between the intensity of a bulb and sunlight is several orders of magnitude. If we are able to properly store the intensity values of light sources and, more importantly, perform all light / surface operations at their appropriate value ranges, we can do true high dynamic range (HDR). When we started experimenting with the new technique about 18 months ago and saw the first results, there was no going back for us, we knew we wanted that in the engine. »
What's up ?
SCS Software: “Each light source is now defined with a realistic value gleaned from real world measurements (we did a ton of sampling with a photometer on various daylight and weather parameters) and lookup tables. In reality, as in the gaming world now, tens of thousands of lux units now illuminate daytime scenes, while at night the ambient light approaches a few lux units. Now we know and have tables to choose from for a street light or a neon at a gas station. "[…]
“We have followed this development path (editor's note: HDR lighting) until we realize that if the results were promising, we won't be able to achieve this without rebalancing ALL existing materials / textures on all objects in the game. When a ray of light is projected onto the surface of an object, what is reflected or refracted depends not only on the properties of the incoming light, but largely on the properties of the object's surface. Over the many years of development, we have accumulated tens of thousands of textures, some from photographic sources in various settings, some hand painted, others through the process of procedural generation in various intelligent tools. [...] The new exposure emulation system is much more sensitive and simply requires physically correct brightness albedo values. Our concrete surface can no longer be some kind of gray, and a tree cannot just be beautiful and green. And that's when a large majority of our art team had to be involved for a major overhaul. "
What needed to be changed?
SCS Software: “After our small team implemented all the necessary code and GPU shader changes, which took many months of experimentation, we had to involve a lot more people. First of all, we had to readjust all the light sources in the world and all the vehicle lights. In many cases, this meant that a game object like an entire factory or a delivery yard with predefined light sources had to be reopened, adjusted, and re-exported back into a 3D tool like Maya. We are talking about thousands and thousands of such retouching, in some cases involving not only a few dozen "numbers" defining the lights, but also major changes in the lightmaps of objects, where false shadows and lighting effects have been " integrated ”for a better look in the old lighting system. Finally, for a few weeks, the majority of all our teams had to stop working on anything related to our future projects, and go through all the game objects, vegetation, vehicles and effects; rebalance things, over and over again, to synchronize them to a shared and agreed upon albedo reference table. We had to revisit the basics of many subsystems, including the vehicle's headlights and bulbs, doing lots of iterations and tweaks to make them look good at various daylight settings. We have a new set of skyboxes at a higher resolution and a slightly richer variety of weather conditions as well. In the end, nothing was overlooked as we had to evaluate and adjust every element of the games. »
“The new lighting system and the start of our new physical lighting model is a critical step towards a complete and better physical model of the whole world in our games. We're not quite at a real physical rendering yet, but update 1.40 is a major step in the right direction. "
“As with every major change, there have been a ton of start-up issues, many dead ends to overcome and our efforts have far exceeded the expectations we had a year ago. We still have a bit of open beta ahead of us to smooth out the last wrinkles. But even now, we believe the changes are worth all the hard work. Just wait to drive your truck early in the morning with the Italian coast, or on a beautiful late afternoon in Sweden, drizzle in Washington state, a scorching midday in Spain, or pulling over in a Well-lit roadhouse deep into the night. Throughout the process of change, we have done our best not to not cause a major increase in the load on the CPU or GPU. A few of the new effects have a slightly higher performance cost, but overall we think the changes are very well balanced, or allow for wise tradeoffs in gameplay options, to maintain acceptable performance. We certainly don't want to lose players and fans who play our games without the latest hardware by pushing too hard on the graphics effects. We can't wait to bring you further improvements and new features, so keep your flywheels! "