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dvwood
01-08-2009, 05:49 AM
I need help with an assignment, what would you guys say to this question?

What of the following is the best way to increase rendering performance (fps)
without changing the appearance of the rendered scene ?
o switch off all light sources
o convert the geometry into triangle strips and use vertex arrays
o use tri-linear texture filtering
o add a specular material property to all surfaces

I would say to add specular material - but i might be wrong.... wouldnt that decrease the fps?

Zengar
01-08-2009, 05:54 AM
Depends on the scene, its complexity, the way it is rendered, the graphics card etc. One of those question you can't answer generally. God, I hate unprofessional multiple-choice questions.

Edit: I am stupid :) Didn't see that "without changing the apperiance" part... I always sucked at tests :(

Jan
01-08-2009, 05:55 AM
Well, to "increase performance" but WITHOUT changing the appearance (AT ALL!) there is really only one option.

Maybe you should write down for each option, what you think what that does and how it changes the appearance, it might get clear to you then.

Jan.

dvwood
01-08-2009, 06:38 AM
Well, lets say that my knowledge is equal to 10% in OpenGL.... a little more help would be appreciated ;-)

I guess its the use of vertex arrays, but why?

IneQuation.pl
01-08-2009, 07:35 AM
o switch off all light sources
Nonsense. Swtiching off lighting may speed up the rendering, but totally changes the appearance of the scene.

o convert the geometry into triangle strips and use vertex arrays
Correct. Triangle strips lead to decreased memory usage (see the Wikipedia article on them). The advantage of vertex arrays (one GL call per each vertex parameter per each larger piece of geometry) over immediate mode (one GL function call per each vertex parameter per every single vertex of the geometry) is the smaller number of GL function calls, which leads to less CPU and system bus bandwidth usage.

o use tri-linear texture filtering
Nonsense. Texture filtering defines the way in which "stretched" textures' pixels are interpolated. Obviously changes the appearance of the scene.

o add a specular material property to all surfaces
Nonsense. This increases lighting quality and may lead to performance reduction rather than improvement. And, it changes the appearance. See the Wikipedia article on specular highlights.

dvwood
01-08-2009, 02:21 PM
Thank you soooo much for the answers!! That made everything clearer. :-)

IneQuation.pl
01-09-2009, 12:17 PM
No problem, glad I helped.