Orthographic vs perspective camera in game dev

A perspective camera renders objects smaller as they get farther away—like your eyes see the world. An orthographic camera flattens depth entirely: a character 10 meters away looks identical in size to one right in front of the lens. Super Paper Mario uses this brilliantly. You play in 2D orthographic mode—just flat platforms left and right. Then Mario flips into 3D, and suddenly that orthographic view becomes perspective, revealing hidden paths and obstacles that were invisible from the 2D angle. The game’s core mechanic is literally just switching between these two projection modes. In Three.js, it’s THREE.PerspectiveCamera vs THREE.OrthographicCamera—the only difference is whether the projection matrix accounts for depth scaling.