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MAS

GPG1 "The Vector Camera" Performance?

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Hi All, I’ve belatedly come across The Vector Camera in Game Programming Gems I (GPG I) by David Paull. It certainly sounds like a theoretical improvement over the “classical” transform and clip pipeline. However, before I make wholesale changes to my (educational) s/w engine, can anyone here confirm that they’ve had success with this approach with regard to performance? For those who don’t have GPG I, the vector camera is defined with the usual UVN vectors to represent the orientation of the camera in world space. The interesting part of the article is the ability to avoid vertex transformations from model to world or from world to view – but simply inverse transform the camera to the world or local space of the object. The author then talks about vectors O, S, and T to define the origin and extents of the view plane. Then a ray plane intersection to get the projected vertex coordinate on the projection plane. The ray is from the origin of the camera to a vertex on the object. Hopefully someone out there is familiar with the article and can comment on their experiences with this approach with regard to performance. Much obliged, Martin.

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I use this camera in my raytracer as it allows a simple way to calculate the rays to fire:

ray.position = O + (S * u) + (T * v)
ray.direction = ray.position - camera.position

As for real world performance or any values I don't know. I've never used it as a real-time camera and don't have any specific profile data for it.

But I like it for it's straightforward, easy to understand and implement approach.

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Guest Anonymous Poster
Hi,

Raytracing, eh? Another "to do" on my list and an interesting one at that. I guess the right thing to do is to make the changes, and have VTune take a look at it and see. Then maybe I can respond to this question when someone else posts it further down the line. Thanks for the response.

Cheers,

Martin.

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