• 1. Computer Graphics
  • 1.1. Screen
  • 1.2. Colours
  • 1.3. Rasterisation
    • 1.3.1. Setting the Colour of a Pixel
    • 1.3.2. Line Rasterisation
    • 1.3.3. Filling Areas
    • 1.3.4. Unit-Summary
  • 1.4. Anti-Aliasing
  • 1.5. Geometric Transformations
  • 1.6. Curves
  • 1.7. Paths
  • 1.8. Self Assessment
  • 1.9. Summary
  • 1.10. Recommended Reading
  • 1.11. Glossary
  • 1.12. Bibliography
  • 1.13. Metadata

1.3.4. Unit-Summary

On a raster display a line is drawn by colouring pixels. Since the pixels are centered around the grid points, we have to approximate the line by intensifying the grid-point pixels lying on the line or nearest to it. There are various algorithms to find the pixels that approximate best the line. Which algorithm have to be applied depends on the slope of the line.

The algorithm for filling polygons contains two steps:

• Computing the intersections for each scan line
• Filling the polygon alternately between the intersections.

Update: 26.1.2012 (eLML) - Contact - Print (PDF) - © CartouCHe 2004-2007 (Creative Commons) - layout based on YAML