Parallax scrolling is a technique in computer graphics where background images move past the camera more slowly than foreground images, creating the illusion of depth in the 2D scene and adding to the sense of immersion in a virtual experience. This technique grew out of the multiplane camera technique used in traditional animation since the 1930s. Parallax scrolling was popularized in 2D computer graphics and video games by the arcade game Moon Patrol and Jungle Hunt both released in 1982. Some parallax scrolling has previously been used by the 1981 arcade game < i> Jump Bug .
Video Parallax scrolling
Metode
There are four main methods of scrolling parallax used in titles for arcade board systems, video game consoles and personal computer systems.
Layer method
Some display systems support multiple background layers that can be scrolled independently in horizontal and vertical directions and are composed on one another, simulating multiplane cameras. In such a display system, the game can generate parallax by simply changing the position of each layer by different amounts in the same direction. The faster moving layer is considered closer to the virtual camera. Layers can be placed in front of playfield - layers that contain objects that interact with players - for various reasons such as to provide dimension enhancements, blur some game action, or distract the player.
Sprite Method
Programmers can also create pseudo-layer sprites - individually controllable moving objects pulled by hardware above or behind the layer - if they are available in the display system. For example Star Force , a vertical scroll shooter for NES, uses this for its star line, and Final Fight for Super NES uses this technique to layer immediately in front of the main playfield The Amiga computer has sprites that can have altitudes and can be arranged horizontally with copper co-processors, which makes it ideal for this purpose. Risky Woods in Amiga uses sprite multiplexing with copper to create an entire layer of full parallax background as an alternative to dual playfield mode system.
Repeating pattern/animation method
Scrolling displays constructed from individual tiles can be made to 'float' over a recurring background layer by animating individual tile bits to capture parallax effects. Bicycle colors can be used to quickly switch tiles across the screen. This software effect gives the illusion of another layer (hardware). Many games use this technique for rolling star fields, but sometimes more complex or multi-directional effects are achieved, as in the game Parallax by Sensible Software.
The raster method
In the raster graph, the pixel lines in an image are usually composite and refreshed in the top-down sequence with little delay (called horizontal blanking intervals) between drawing a line and drawing the next line. Games designed for older graphics chipsets - such as third and fourth generation of video game consoles, special TV games, or those with similar handheld systems - take advantage of raster characteristics to create the illusion of more layers.
Some display systems have only one layer. This includes most of the classic 8-bit systems (such as Commodore 64, Nintendo Entertainment System, Sega Master System, PC Engine/TurboGrafx-16 and original Game Boy). More sophisticated games on such systems generally divide the layers into horizontal strips, each with different scrolling positions and speeds. Typically, higher strips on the screen will represent things farther away from virtual cameras or a strip will be held still to display status information. The program will then wait for the horizontal blank and change the scroll layer position just before the display system starts drawing each scanline. These are called "raster effects" and are also useful for changing the system palette to provide a gradient background.
Some platforms (such as Commodore 64, Amiga, Sega Master System, PC Engine/TurboGrafx-16, Sega Mega Drive/Genesis, Super NES, Game Boy, Game Boy Advance and Nintendo DS) provide horizontal blank interruptions for settings automatically register independently of the rest of the program. Others, such as NES, require the use of cycle time codes, specifically written to take the exact same time to run when the video chip takes a single scanline image, or a timer inside the game cartridge that generates an interrupt after a certain number of scanlines has been pulled. Many NES games use this technique to draw their status bar, and Teenage Mutant Ninja Turtles II: Arcade Game and Vice: Project Doom for NES use it to scroll the background layer at the level different.
More sophisticated raster techniques can produce interesting effects. A system can achieve a very effective depth of field if a layer with a raster is combined; Sonic the Hedgehog , Sonic The Hedgehog 2 , ActRaiser , Lionheart and Street Fighter II >> use this effect well. If each scanline has its own layer, a Pole Position effect is generated, which creates a pseudo-3D (or pseudo-3D ball court as in NBA Jam ) path on a 2D system. If the display system supports rotation and scaling in addition to scrolling - a popular effect known as Mode 7 - change the rotation and scale factor can pull the plane projection (as in F-Zero and Super Mario Kart ) or can playfield play to create additional challenge factors.
Another advanced technique is the scrolling of rows/columns, where the tile rows/columns on the screen can be scrolled one by one. This technique is implemented in graphics chips from various Sega arcade system boards since Sega Space Harrier and System 16, Sega Mega Drive/Genesis console, and Capcom CP System, Irem M-92 and Taito F3 System arcade game board.
Maps Parallax scrolling
Example
In the following animation, the three layers move to the left at different speeds. Their speed decreases from front to back and corresponds to an increase in relative distance from the viewer. The soil layer moves 8 times faster than the vegetation layer. The vegetation layer moves twice as fast as the cloud layer.
This is a working prototype, using the elements below, showing the horizontal parallax effect: https://app.atomic.io/d/YK1KYdulLLZz
Parallax scrolling in Web design
Web designers began to incorporate rolling parallaxes in 2011, using HTML5 and CSS3 coding. Advocates argue it is a simple way to embrace Web fluidity. Supporters use parallax backgrounds as a tool to better engage users and improve the overall experience the website provides. However, a Purdue University study, published in 2013, reveals the following findings: "... although parallax scrolling improves certain aspects of the user experience, it does not necessarily improve the overall user experience".
See also
- 2.5D
- Scrolling
References
Source of the article : Wikipedia
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