The history of video game Graphics has been a steady march towards reality simulation. We began with white lines and dots on black backgrounds, now we have games rendered in 4K resolution. Sure, there are problems with the animation or art style in some games. There was that slightly unsettling period, in the middle of the journey, where we camped in the uncanny valley, but on the whole, our ability to represent the real world has been steadily increasing since the beginning and we haven't stopped getting closer to having photo-realistic graphics in the virtual world.

This is where DirectX raytracing comes in. With it, we can reach a new level of graphical detail.

What is ray tracing?

Ray tracing is a technique for rendering graphics based on tracing the path of photons that bounce off of an object in order to create an image based on them. Fundamentally, this is how we perceive the world in reality. Light bounces off of an object and hits the retina, then the light is used to produce an image in our brain. There is a problem, however. A tiny percentage of the photons fired from a light source reach an object and a tiny percentage of the ones that hit bounce and reach our eyes. While it is technically possible to run an algorithm that models all of the photons, it's slow and inefficient.

There is a solution to this. Instead of modeling every possible photon, only model those that would reach the camera. This can be done by tracing the photons in reverse- from the camera back to the origin point. This limits the algorithm to only the photons which would have hit the camera. Rendering graphics in this manner can give us a near photo-realistic image.

It is, however, a very intensive process which can take time for a computer to calculate. This is why, for a long time, we haven't been using it for video games.

What we're using now?

Currently, 3D computer graphics are created primarily through rasterization. Rasterization is just the process of converting the mapping from scene geometry into pixels.

It is currently used instead of ray tracing because it is much faster in practice. This speed comes at the expense of detail, however, while it has gotten increasingly more detailed, its goal is to create a smooth approximation of reality, not complete photo-realism. Rasterization makes 2D pixels from 3D graphics, and so, it requires shaders to produce an adequate quality of light. The result is that light and shading effects produced by rasterization will never be fully realistic. This is where DirectX Raytracing comes in.

Why is it important?

DirectX Raytracing is important because it bridges the gap between ray tracing and rasterization. While we will still not be able to shift into using on-the-fly ray tracing entirely for video games, we will be able to use it, to a limited extent, in order to create much more detailed and immersive worlds.

It is not the graphical revolution in itself but a step towards it. What begins as better textures and shading effects now will in time lead to full global illumination which allows not only for the direct bouncing of the photons to the camera but also for the photons bouncing off of other objects. This increases the detail, even more, allowing us to see things which do not directly fire photons towards the camera. It will still be a long time before rasterization becomes a less practical method of creating 3D environments, but eventually, ray tracing could become the dominant method for creating truly immersive and realistic worlds.
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