Search results
Results from the WOW.Com Content Network
A fractal landscape being rendered using the painter's algorithm on an Amiga. The painter's algorithm (also depth-sort algorithm and priority fill) is an algorithm for visible surface determination in 3D computer graphics that works on a polygon-by-polygon basis rather than a pixel-by-pixel, row by row, or area by area basis of other Hidden-Surface Removal algorithms.
The rule can be seen in effect in many vector graphic programs (such as Freehand or Illustrator), where a crossing of an outline with itself causes shapes to fill in strange ways. On a simple curve, the even–odd rule reduces to a decision algorithm for the point in polygon problem.
This algorithm is sometimes also known as the crossing number algorithm or the even–odd rule algorithm, and was known as early as 1962. [3] The algorithm is based on a simple observation that if a point moves along a ray from infinity to the probe point and if it crosses the boundary of a polygon, possibly several times, then it alternately ...
A variant called boundary fill uses the same algorithms but is defined as the area connected to a given node that does not have a particular attribute. [1] Note that flood filling is not suitable for drawing filled polygons, as it will miss some pixels in more acute corners. [2] Instead, see Even-odd rule and Nonzero-rule.
The Greiner-Hormann algorithm is used in computer graphics for polygon clipping. [1] It performs better than the Vatti clipping algorithm, but cannot handle degeneracies. [2] It can process both self-intersecting and non-convex polygons. It can be trivially generalized to compute other Boolean operations on polygons, such as union and difference.
Given polygon A as the clipping region and polygon B as the subject polygon to be clipped, the algorithm consists of the following steps: List the vertices of the clipping-region polygon A and those of the subject polygon B. Label the listed vertices of subject polygon B as either inside or outside of clipping region A.
All steps for clipping concave polygon 'W' with a 5-sided convex polygon. The Weiler–Atherton algorithm overcomes this by returning a set of divided polygons, but is more complex and computationally more expensive, so Sutherland–Hodgman is used for many rendering applications. Sutherland–Hodgman can also be extended into 3D space by ...
A curve (top) is filled according to two rules: the even-odd rule (left), and the non-zero winding rule (right). In each case an arrow shows a ray from a point P heading out of the curve.