Back in 2014, Imagination Technologies announced its PowerVR GR6500 ray-tracing GPU. That design taped out in July last year, and now the company is showing some actual real-time ray tracing demos using the Unity 5 engine and the GR6500 GPU at MWC 2016.
Ray tracing has long been a staple of high-end 3D graphical work. Put simply, the technique involves casting virtual rays of light on a scene and accurately calculating where and how they will land, which shadows they will cast, and how they bounce off of reflective surfaces. The technique allows for highly realistic graphics, but it's also extremely computationally intensive. As a result, it's usually reserved for movie work and 3D artistry.
Time and again, players from different parts of the graphics industry have promised a "holy grail" real-time ray tracer, but those promises have never really panned out. Imagination Technologies' efforts seems to have a little more substance, though. The company has working silicon in the shape of the GR6500 GPU, and already offers software integration with several software packages, including the Unity 5 game engine.
The GR6500 allows for a hybrid raster and ray-tracing approach that can easily deal with dynamic geometry, as in the case of the animated zombies below. In Imagination's own words:
The PowerVR GR6500 GPU can easily cope with fully dynamic geometry. This is because the PowerVR Wizard architecture features a dedicated scene hierarchy generator that receives data directly from the shading output. The Unity engine performs dynamic skinning to animate the zombies using a vertex shader, and then the vertex positions are fed into the scene hierarchy generator to assemble the scene acceleration structure in real-time.
The company says using ray tracing combined with normal rasterization techniques makes the graphics artists' job a lot easier, as they don't have to worry much about shadow and reflection maps in particular. They just have to configure an object's physical characteristics, and the ray tracer will do its thing. That simplicity is demonstrated in the monster truck demo below. Imagination says the scene's developer didn't have to create specific graphical assets for the reflections on the truck and balls, for example.
Imagination Technologies also demonstrates how easy it is for its ray tracing engine to add realistic reflections to a traditional rasterized scene:
Ray tracing isn't all about the pretties, though. With shadows and reflections being calculated in real time, there's little need to burn precious VRAM or bandwidth shifting a ton of texture maps around. Imagination promises substantial power savings, too, as ray traced shadows can end up being computationally cheaper than the cascaded shadow mapping techniques currently in use. The company also claims the PowerVR GR6500 can scale to "multi-core, multi-cluster configurations" capable of powering a console or desktop PC.