Short answers, pulled from the story.
Real-time computer graphics is defined by the mathematical constraint that the computer must generate each frame in less than one-thirtieth of a second to maintain the illusion of motion. This requirement separates the field from traditional rendering systems that spend hours or days calculating lighting for a single image. The technology prioritizes speed over perfection to ensure the next frame arrives before the user notices the delay.
Real-time computer graphics evolved from generating simple two-dimensional lines and shapes to using sprites that mimicked three-dimensional objects. The industry later shifted to z-buffer triangle rasterization which decomposes objects into individual triangles and generates pixels inside them. Modern graphics processing units handle millions of triangles per frame by using techniques like texture mapping and shadow mapping to alter colors based on light sources.
The rendering pipeline in real-time computer graphics is divided into the application stage, the geometry stage, and the rasterization stage. The application stage handles collision detection and user input while preparing graphics data for the next phase. The geometry stage manipulates polygons and vertices to compute what to draw and where to draw it before the rasterization stage applies color and turns elements into pixels.
Real-time computer graphics transforms the three-dimensional scene into view space where the observer or camera is placed at the origin looking in the direction of the negative z-axis. The system uses orthographic projection where parallel lines remain parallel or perspective projection which makes models appear smaller as the distance increases. After projection the system performs clipping to remove primitives outside the view box before the rasterizer draws the remaining primitives into new triangles.
Real-time computer graphics optimizes image quality subject to strict time and hardware constraints while offline rendering remains much more accurate. In real-time computer graphics the user operates an input device to influence what is drawn on the display whereas a director has complete control in film production. The disparity between the fast response time of human motion and the slow perspective speed of the human visual system drives the development of faster input devices.