Author Topic: (GDC 2018) Announcing Microsoft DirectX Raytracing  (Read 1335 times)

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(GDC 2018) Announcing Microsoft DirectX Raytracing
« on: March 21, 2018, 05:59:32 PM »
For the last thirty years, almost all games have used the same general technique—rasterization—to render images on screen.  While the internal representation of the game world is maintained as three dimensions, rasterization ultimately operates in two dimensions (the plane of the screen), with 3D primitives mapped onto it through transformation matrices.  Through approaches like z-buffering and occlusion culling, games have historically strived to minimize the number of spurious pixels rendered, as normally they do not contribute to the final frame.  And in a perfect world, the pixels rendered would be exactly those that are directly visible from the camera.

Through the first few years of the new millennium, this approach was sufficient.  Normal and parallax mapping continued to add layers of realism to 3D games, and GPUs provided the ongoing improvements to bandwidth and processing power needed to deliver them.  It wasn’t long, however, until games began using techniques that were incompatible with these optimizations.  Shadow mapping allowed off-screen objects to contribute to on-screen pixels, and environment mapping required a complete spherical representation of the world.  Today, techniques such as screen-space reflection and global illumination are pushing rasterization to its limits, with SSR, for example, being solved with level design tricks, and GI being solved in some cases by processing a full 3D representation of the world using async compute.  In the future, the utilization of full-world 3D data for rendering techniques will only increase.

Today, we are introducing a feature to DirectX 12 that will bridge the gap between the rasterization techniques employed by games today, and the full 3D effects of tomorrow.  This feature is DirectX Raytracing.  By allowing traversal of a full 3D representation of the game world, DirectX Raytracing allows current rendering techniques such as SSR to naturally and efficiently fill the gaps left by rasterization, and opens the door to an entirely new class of techniques that have never been achieved in a real-time game.