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  ST Micro's Kyro II & Hercules' 3D Prophet 4500 
  Jun 18, 2001, 09:00am EDT 
 

Rendering Overview


By: Dan Mepham

In case you found the last two pages somewhat confusing, hereís a graphical overview comparing the two rendering methods. Suppose we want to render a scene that consists of three 3-dimensional shapes as shown. Each shape may be composed of hundreds or even thousands of polygons.

http://media.hardwareanalysis.com/articles/small/10132.gif" alt="Sample Shapes" border=0>

The Immediate mode renderer would simply render and texture each polygon in each shape separately, then check their depths against the z-buffer in order to decide which ones are at the front and which are at the back. Once it realizes that the yellow triangle is at the front, followed by the blue circle, with the red square at the back, it will draw the scene, and simply discard the parts of the blue circle and red square that arenít visible. Very clean and very easy, however it means that the card wasted time rendering and texturing part of the blue circle, and at least half of the red square, when they werenít visible to begin with.

http://media.hardwareanalysis.com/articles/small/10133.gif" alt="Immediate Mode" border=0>

By contrast, the Tile-based renderer checks the objectsí depth (z-position) first, and then renders and textures only the parts of those objects that will be visible. In other words, the polygons that compose the right-hand side of the red square are never rendered or textured.

http://media.hardwareanalysis.com/articles/small/10134.gif" alt="Tile-Based" border=0>

Itís visibly more efficient, particularly in a complex scene where there are polygons on top of polygons on top of other polygons. However, as previously stated, making sure the correct polygons are drawn is no small task. For example, suppose you wanted to draw a pool of water. The Tile renderer would have to realize that the polygons that make up the water are clear, and therefore that it needs to draw the polygons behind those clear polygons (the cement foundation of the pool) as well, even though there are other polygons in front of them.



1. Introduction
2. The 3rd Dimension, Bringing Worlds to Life
3. Immediate Mode Rendering, The Industry Standard
4. Tile-Based Rendering, A New Approach
5. Rendering Overview
6. ST Microelectronics' Kyro II
7. Hercules 3D Prophet 4500
8. Test Setup & Procedure
9. Performance - Fill-rates & 3DMark
10. Performance - Quake 3 Arena
11. Performance - Mercedes Benz Truck Racing
12. Performance - Unreal Tournament
13. Performance - SPECviewperf
14. CPU Scaling Performance
15. FSAA Performance - Quake 3 Arena
16. FSAA Performance - Unreal Tournament
17. Summary

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  Product Ratings 
 
Imagination/ST Microelectronics Kyro II
Performance: 7/10
Stability: 10/10
Features: 3/10
Price: 10/10
Overall Rating: 9/10
Hercules 3D Prophet 4500
Performance: 7/10
Stability: 10/10
Quality: 10/10
Features: 4/10
Documentation: 7/10
Price: 10/10
Overall Rating: 9/10
 

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