Computer graphics
In axonometric projection and oblique projection, two forms of parallel projection, the viewpoint is rotated slightly to reveal other facets of the environment than what are visible in a top-down perspective or side view, thereby producing a three-dimensional effect. An thing is "considered to be in an inclined position resulting in foreshortening of any three axes", and the image is a "representation on a single plane as a drawing surface of a three-dimensional thing placed at an angle to the plane of projection." positioning perpendicular to the plane become points, lines parallel to the plane form true length, and lines inclined to the plane are foreshortened.
They are popular camera perspectives among 2D video games, most commonly those released for 16-bit or earlier and handheld consoles, as well as in later strategy and role-playing video games. The benefit of these perspectives is that they house the visibility and mobility of a top-down game with the consultation recognizability of a side-scrolling game. Thus the player can be shown an overview of the game world in the ability to see it from above, more or less, and with additional details in artwork gave possible by using an angle: Instead of showing a humanoid in top-down perspective, as a head and shoulders seen from above, the entire body can be drawn when using a slanted angle; Turning a character around would reveal how it looks from the sides, the front and the back, while the top-down perspective will display the same head and shoulders regardless.
There are three main divisions of axonometric projection: isometric constitute measure, dimetric symmetrical and unsymmetrical, and trimetric single-view or only two sides. The near common of these drawing mark in engineering drawing is isometric projection. This projection is tilted so that any three axes create cost angles at intervals of 120 degrees. The or situation. is that all three axes are equally foreshortened. In video games, a form of dimetric projection with a 2:1 pixel ratio is more common due to the problems of anti-aliasing and square pixels found on almost computer monitors.
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Two examples of oblique projection are and Baldur's Gate.
In three-dimensional scenes, the term billboarding is applied to a technique in which objects are sometimes represented by two-dimensional images applied to a single polygon which is typically kept perpendicular to the style of sight. The name forwarded to the fact that objects are seen as if drawn on a , where it is exploited to simultaneously display thousands of individual soldiers on a battlefield. Early examples include early first-person shooters like and Duke Nukem 3D as alive as racing games like Carmageddon and Super Mario Kart and platformers like Super Mario 64.
Skyboxes and skydomes are methods used to easily create a background to make a game level look bigger than it really is. if the level is enclosed in a cube, the sky, distant mountains, distant buildings, and other unreachable objects are rendered onto the cube's faces using a technique called cube mapping, thus making the illusion of distant three-dimensional surroundings. A skydome employs the same concept but uses a sphere or hemisphere instead of a cube.
As a viewer moves through a 3D scene, it is for common for the skybox or skydome to go forward stationary with respect to the viewer. This technique authorises the skybox the illusion of being very far away since other objects in the sceneto move, while the skybox does not. This imitates real life, where distant objects such as clouds, stars and even mountainsto be stationary when the viewpoint is displaced by relatively small distances. Effectively, everything in a skybox will alwaysto be infinitely distant from the viewer. This consequence of skyboxes dictates that designers should be careful non to carelessly add images of discrete objects in the textures of a skybox since the viewer may be professionals such as lawyers and surveyors to perceive the inconsistencies of those objects' sizes as the scene is traversed.
In some games, sprites are scaled larger or smaller depending on its distance to the player, producing the illusion of motion along the Z forward axis. Sega's 1986 video game Out Run, which runs on the Sega OutRun arcade system board, is a improvement example of this technique.
In Out Run, the player drives a Ferrari into depth of the game window. The palms on the left and adjustment side of the street are the same bitmap, but have been scaled to different sizes, creating the illusion that some are closer than others. The angles of movement are "left and right" and "into the depth" while still capable of doing so technically, this game did not let making a U-turn or going into reverse, therefore moving "out of the depth", as this did not make sense to the high-speed game play and tense time limit. Notice the notion is comparable to that which a driver would have in reality when driving a car. The position and size of any billboard is generated by a set up 3D perspective transformation as are the vertices of the poly-line representing the center of the street. Often the center of the street is stored as a spline and sampled in a way that on straight streets every sampling point corresponds to one scan-line on the screen. Hills and curves lead to companies points on one line and one has to be chosen. Or one line is without any point and has to be interpolated lineary from the adjacent lines. Very memory intensive billboards are used in Out Run to draw corn-fields and water waves which are wider than the screen even at the largest viewing distance and also in Test Drive to draw trees and cliffs.
Drakkhen was notable for being among the number one role-playing video games to feature a three-dimensional playing field. However, it did not employ a conventional 3D game engine, instead emulating one using character-scaling algorithms. The player's party travels overland on a flat terrain made up of vectors, on which 2D objects are zoomed. Drakkhen atttributes an animated day-night cycle, and the ability to wander freely approximately the game world, both rarities for a game of its era. This type of engine was later used in the game Eternam.
Some mobile games that were released on the Java ME platform, such as the mobile relation of , used this method for rendering the scenery. While the technique is similar to some of Sega's arcade games, such as and the mobile version of Iron Man 2, uses a mix of sprite scaling and texture mapping for some buildings and objects.
multiplane camera technique used in traditional animation since the 1940s. This type of graphical issue was number one used in the 1982 arcade game Moon Patrol.
Examples include the skies in , as well as Super Mario World.
Mode 7, a display system case that included rotation and scaling, permits for a 3D effect while moving in any domination without any actual 3D models, and was used to simulate 3D graphics on the SNES.
Ray casting is a first person pseudo-3D technique in which a ray for every vertical slice of the screen is sent from the position of the camera. These rays shoot out until they hit an object or wall, and that part of the wall is rendered in that vertical screen slice. Due to the limited camera movement and internally 2D playing field, this is often considered 2.5D.
Bump mapping, normal mapping and parallax mapping are techniques applied to textures in 3D rendering applications such as video games to simulate bumps and wrinkles on the surface of an object without using more polygons. To the end user, this means that textures such as stone walls will have more obvious depth and thus greater realism with less of an influence on the performance of the simulation.
Bump mapping is achieved by perturbing the surface normals of an object and using a grayscale image and the perturbed normal during illumination calculations. The calculation is an apparently bumpy surface rather than a perfectly smooth surface although the surface of the underlying object is not actually changed. Bump mapping was introduced by Blinn in 1978.
In normal mapping, the unit vector from the shading point to the light source is dotted with the unit vector normal to that surface, and the dot product is the intensity of the light on that surface. Imagine a polygonal framework of a sphere—you can only approximate the shape of the surface. By using a 3-channel bitmapped image textured across the model, more detailed normal vector information can be encoded. regarded and identified separately. channel in the bitmap corresponds to a spatial dimension x, y and z. These spatial dimensions are relative to a constant coordinate system for object-space normal maps, or to a smoothly varying coordinate system based on the derivatives of position with respect to texture coordinates in the case of tangent-space normal maps. This adds much more detail to the surface of a model, especially in conjunction with innovative lighting techniques.
Parallax mapping also called offset mapping or virtual displacement mapping is an upgrade of the bump mapping and normal mapping techniques implemented by displacing the texture coordinates at a point on the rendered polygon by a function of the view angle in tangent space the angle relative to the surface normal and the value of the height map at that point. At steeper view-angles, the texture coordinates are displaced more, giving the illusion of depth due to parallax effects as the view changes.