Download presentation

Presentation is loading. Please wait.

Published byTatiana Ferring Modified over 2 years ago

1
**Basic Raster Graphics Algorithms for Drawing 2D Primitives**

Prof. Lizhuang Ma Shanghai Jiao Tong University

2
**Contents Architecture of a Raster Display Scan Converting Lines**

Filling Rectangles Filling Polygons Clipping Lines Clipping Polygons Antialiasing

3
**Architecture of a Raster Display Video**

4
**Definitions Pixel: a screen consists of N x M pixels**

Bilevel = monochrome, 1 bit / pixel Color: RGB/CYK/LUV… Bitmap / pixmap Frame buffer: an array of data in memory mapped to screen

5
Scan Converting Line A scan-converted line showing intensified pixels as black circles

6
**The Basic Incremental Algorithm**

A scan-converted line showing intensified pixels as black circles

7
**The Basic Incremental Algorithm**

void Line (intx0, inty0, intx1, inty1, value) { intx; floatdy, dx, y, m; dy=y1-y0; dx=x1-x0; m=dy/dx; y=y0; for(x=x0; x<=x1; x++) { WritePixel(x, (int)floor(y+0.5), value); y+=m; }

8
**Midpoint Line Algorithm**

9
**Midpoint Line Algorithm**

10
**Midpoint Line Algorithm**

void MidpointLine(intx0, inty0, intx1, inty1, value) { int dx, dy, incrE, incrNE, d, x, y; dy=y1-y0;dx=x1-x0;d=dy*2-dx; incrE=dy*2;incrNE=(dy-dx)*2; x=x0;y=y0; WritePixel(x, y, value); while(x<x1) { if(d<=0) {d+=incrE;x++; } else {d+=incrNE;x++;y++;

11
**Filling Rectangles for(y from ymin to ymax of the rectangle) {**

for(x from xmin to xmax) { WritePixel(x, y, value); }

12
Filling Polygons

13
Filling Polygons

14
Filling Polygons Find the intersections of the scan line with all edges of the polygon Sort the intersections by increasing x coordinate Fill in all pixels between pairs of intersections that lie interior to the polygon

15
Special Cases Slivers Horizontal Edges

16
Clipping Lines

17
**The Cohen-Sutherland Algorithm**

18
**The Cohen-Sutherland Algorithm**

19
Clipping Polygons

20
**The Sutherland-Hodgman Polygon-Clipping Algorithm**

22
Antialiasing

Similar presentations

OK

Scan Conversion of Line Segments. What is Scan conversion? Final step of rasterization (the process of taking geometric shapes and converting them into.

Scan Conversion of Line Segments. What is Scan conversion? Final step of rasterization (the process of taking geometric shapes and converting them into.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on satellites launched by india Ppt on new zealand culture music Ppt on general knowledge quiz Ppt on conservation of momentum formula Perspective view ppt on ipad Ppt on energy giving food group Ppt on interest rate risk management Ppt on acid-base titration indicator Friction for kids ppt on batteries Ppt on indian festivals in hindi