From: Christopher Phillips (
Date: 2004-11-07 08:17:31

On 7 Nov 2004, at 00:08, Groepaz wrote:

>> So if I used this method my hardware would have 320 X coordinates
>> and 200 Y coordinates.  What if one of the points is outside of this
>> area, say -20,50?  Is the hardware expected to be able to deal with
>> points outside off 200 x 320 and fill the part of the triangle that 
>> is in
>> the
>> visible area or does the coder somehow take care of this?
> thats usually encapsulated (?) by the underlaying API - depends on the
> GPU if that operation is hardware-accelerated or if triangle 
> subdividing
> is done in software. you probably dont want to implement this in 
> hardware,
> since the operation isnt exactly simple.

Indeed.  That said though, it's not too uncommon for hardware to 
support coordinates that cover a larger area (say 512x512), and for it 
to only enable writes to coordinates that fall within the screen area, 
which is defined to be a window within the larger area.

For example, the playstation one actually spends a cycle or two per 
pixel filled even for points off the left side of the screen, as the 
hardware is too stupid to be able to compute the colour or texture 
coordinates to use for the first pixel it actually plots without 
looping through the hidden part of the span first :)

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