Gamers don't see it that way though because often, faked reflections are "good enough".
In some cases though, the faked reflections are noticeable and immersion breaking. I notice it in MS Flight Simulator. I'm flying over water and approaching a large city, and I can see the reflection of buildings in the water. But when I push the nose down, as the image of the buildings goes off the top of my screen, the reflections go away too. In reality, this wouldn't happen. But in the sim, it does because the reflections are generated by just inverting the rendered image of the buildings.
There's a map in Apex Legends where a section has a shiny floor. It fakes a reflection by rendering an environment-mapped texture. It does a decent job at making the floor look like it's reflective, but as you move around and compare what's being rendered to the actual geometry, you notice how it falls apart. But in a competitive FPS, you're not looking at the environment long and hard enough to notice.
Duke Nukem 3D had proper reflections, but it did it by actually mirroring all the geometry, a technique that only really works well if the geometry is simple.
Gamers don't see it that way though because often, faked reflections are "good enough".
In some cases though, the faked reflections are noticeable and immersion breaking. I notice it in MS Flight Simulator. I'm flying over water and approaching a large city, and I can see the reflection of buildings in the water. But when I push the nose down, as the image of the buildings goes off the top of my screen, the reflections go away too. In reality, this wouldn't happen. But in the sim, it does because the reflections are generated by just inverting the rendered image of the buildings.
There's a map in Apex Legends where a section has a shiny floor. It fakes a reflection by rendering an environment-mapped texture. It does a decent job at making the floor look like it's reflective, but as you move around and compare what's being rendered to the actual geometry, you notice how it falls apart. But in a competitive FPS, you're not looking at the environment long and hard enough to notice.
Duke Nukem 3D had proper reflections, but it did it by actually mirroring all the geometry, a technique that only really works well if the geometry is simple.
RT makes reflections Just Work and work properly.