What Is Scanline Rendering?


In 3D computer graphics, there is a visible surface determination which works on a row by row basic in the animation of a character instead of a pixel by pixel basis or polygon by polygon basis. This is called scanline rendering. This is where the polygons that are to be rendered will first be sorted by a coordinate called the top y and at the point where they first appear, then each row or scan line of the image is processed using the intersection of this scan line with the polygons on the front of the sorted list. The sorted list is then updated to discard the polygons that are no longer visible and the active scan line is advanced down the picture.

In scanline rendering, it usually starts with edges of projected polygons which are inserted into buckets, one per scanline. There are many other technical processes that involve the scanline rendering. A little bit of an easier way to explain this form of rendering is each graphic or animation can be broken down in pixels which covers the whole image but it can also be broken down in lines which are the connection of two graphic chips within the image. This is a way of rendering the individual lines. One of the graphic chips handles the odd numbered lines while the other chip handles the rendering of the even number lines. This process makes the frame rate of the animation much faster but the memory that is needed for this animation is much higher than a regular rendering animation.

When speaking of the scanline rendering, there is also rasterisation which is better than the pixel by pixel approach because it uses the primitive by primitive approach to rendering because this is the rendering method that is used by most of the graphics cards that you get today. In this form of scanline rendering, one primitive loops through each of the other primitives and it determines which pixels in image that its movement affects and modifies those pixels accordingly to what is needed.

There is a lot of learning that needs to take place when you need to fully understand the process of scanline rendering and the rasterisation of images in any kind of graphic or animation. Terms can get very technical and if you do not understand even one simple term that is used, then the rest of the processes will just be out of this world to you.

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