Are we addicted to graphics power? Are Nvidia and AMD, in reality, the pushers of the most addictive shader skag?
In any other walk of life you'd be dragged off to rehab for this intensely self-destructive cycle of substance abuse. But just like that heroin addict, who's currently trying to break into your home and steal your pride and joy gaming system, the PC industry is addicted to graphics.
Luckily for your average 7MHz, 16-bit processor, vectors can be manipulated using simple matrices functions, so they can be scaled and rotated in our imaginary space before being drawn to the screen. But lines aren't very exciting, unless they're white and Bolivian in origin.
As a stepping stone to true 3D, Doom and its clones were based on 2D maps that had simple height information and the actual 3D effect were a textured wall projection. Similarly, the monsters were flat bitmaps positioned on that same 2D map, scaled according to their distance from the player.
NOT SO ELITE: Graphics have come a long way since the dark days of 1982
This combined with pseudo lighting effects enabled id Software to generate a basic, fully textured 3D world on a lowly 386 PC. Faster processors have enabled devs to combine the texture handling used in Doom with a true full 3D Vector Engine to create the likes of Descent in 1995, and in 1996, the seminal Quake.
But despite all the cleverness of these engines, incredibly basic abilities, such as texture filtering were and remain simply too processor intensive for a standard CPU to even consider attempting in real time.
Acceleration heaven
The first time our gelatinous eyeballs gazed upon the smooth textures and lighting effects in Quake or the explosive effects of Incoming, we were hooked. It was these types of effects and abilities that enabled a mid-nineties PC to pull off arcade-level graphics.
While not wanting to delve into degree level subjects, to really understand why graphics cards exist as they do today, it's helpful to know what's required to create that eye-pleasing 3D display we so enjoy. As you'll see graphics cards started with handling only a fraction of the total process, up until today where they embrace almost the entire task.
We've already mentioned vectors and how they can be used to build up models from triangular meshes. You start here with your models, these need to be transformed and scaled to fit into a virtual 'world view', the application then applies a 'view space', which is how the player will view this world. It's a pyramid volume cut out of the world space and bounds the only area of interest to the renderer.
From this pyramid we get the clipping space, which is the visible square of our virtual viewport and finally these are translated into the screen space where the 2D x/y coordinates are calculated ready for the pixel rendering. These steps are important as originally this was done on the CPU, but stages were slowly shifted to the GPU. So are you still with us?
As that's the simple part, each of those 'views' is required for different stages in rendering. For instance, to help optimise the rendering it makes sense to discard all the undrawn triangles. Occlusion culling will remove obscured objects, trivial clipping removes objects outside the 'view space' and finally culling determines which triangles are facing away from the viewer and so can be ignored.
The clipping space view is created from this remaining world space and any models that bisect the viewing boundary box need to be clipped off and retessellated, leaving only the visible triangles in the final scene.