Search results
Results from the WOW.Com Content Network
The simplest method of drawing a line involves directly calculating pixel positions from a line equation. Given a starting point (,) and an end point (,), points on the line fulfill the equation = +, with = = being the slope of the line. The line can then be drawn by evaluating this equation via a simple loop, as shown in the following pseudocode:
A naive approach to anti-aliasing the line would take an extremely long time. Wu's algorithm is comparatively fast, but is still slower than Bresenham's algorithm. The algorithm consists of drawing pairs of pixels straddling the line, each coloured according to its distance from the line. Pixels at the line ends are handled separately.
Clipping, in the context of computer graphics, is a method to selectively enable or disable rendering operations within a defined region of interest. Mathematically, clipping can be described using the terminology of constructive geometry .
The Nicholl–Lee–Nicholl algorithm is a fast line-clipping algorithm that reduces the chances of clipping a single line segment multiple times, as may happen in the Cohen–Sutherland algorithm. The clipping window is divided into a number of different areas, depending on the position of the initial point of the line to be clipped.
An outcode is computed for each of the two points in the line. The outcode will have 4 bits for two-dimensional clipping, or 6 bits in the three-dimensional case. The first bit is set to 1 if the point is above the viewport. The bits in the 2D outcode represent: top, bottom, right, left.
The line segment may then be re-translated and/or re-rotated to bring it to the original position. After that, straight line segments are drawn from the line end point, passing through the corners of the clipping window. These areas are then designated as L, LT, LB, or TR, depending on the location of the initial point. Then the other end point ...
Here the parametric equation of a line in the view plane is = + where . Now to find the intersection point with the clipping window, we calculate the value of the dot product . Let p E {\displaystyle \mathbf {p} _{E}} be a point on the clipping plane E {\displaystyle E} .
Considering the rendering pipeline, the projection, the clipping, and the rasterization steps are handled differently by the following algorithms: Z-buffering During rasterization, the depth/Z value of each pixel (or sample in the case of anti-aliasing, but without loss of generality the term pixel is used) is checked against an existing depth ...