Hello all, First I want to thank NeHe (and others) for his (their) tutorials on OpenGL, they really help! Second I can use some help, and I am sorry if it has already been explained before, but I do not have the time to browse through all those pages. These are my questions: 1. Are objects renderd in OpenGL when they are not visble? 1b. If not, is it possible to mimic such a feature? 2. I want to create a good looking Phaser effect (from Star Trek) and these are the functions I intend on giving them: 2.1 I want to calculate the closest vertex coords from a given object (the Phaser arrays are objects in my game) to another, I know this is possible, it has been done in another game, but that is in DX8. 2.2 I want to give it a charging up effect on a given object, so the effect starts from both ends untill the location that is calculated with the formula in question 2.1, so both ends will have diffrent speeds. 3. I want to mimic the light blur of a Ship going to Warp, but I want to make it so that the other objects are not affected of this, I have an image of this: [IMG]http://www.startrek.com/library/movies/art/ix_poster_full.jpg[/IMG] Look at the ship, but not the rest. So do you know the awnsers to my questions, or do you know a tutorial of a similar effect, or have you made a demo of such an effect (and willing to give me explanation and/or the source code), please say so here, or E-mail me at mldaalder@hotmail.com Or if NeHe is looking here, then could you make a tutorial on any of the effects? Thank you for your time, mldaalder, Creator of: Science Fiction Career Percent finnished: 0.1% Site: comming soon Forum: comming soon

Hi. Here are the answers to the questions I can answer.
1. Yes. Objecs are draw even when not visible.
1b Yes u can do it. goto http://www.gametutorials.com and look at the OpenGL tut on frustrum culling.
2. I have no idea what a phaser effect looks like so I can;''t hlp
3. Yea it can be done, but it is kind of hard if you are a real newbie. Once u get good enough with OGL, that effect should be nothing;

quote:

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Original post by mldaalder
1. Are objects renderd in OpenGL when they are not visble?

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Just wondering, isn''t that what clipping does?

The objects are not rendered, but this decision is made in the gfx card, so you would still be wasting bus bandwidth passing data outside the screen down and therefore reducing performance.

Ok, I''m still pretty new at this, so I might be mistaken, but I thought clipping was not drawing objects, that would be visible if they weren''t blocked by another object closer to the camera (ie. a man standing behind a brick wall, doesn''t need to be rendered, because you obviously can''t see him without X-ray vision...;P)

What goes to objects behind the camera, I am thinking something like Anonymous Poster, but I''m not sure at all...

Either way: why would you want to render objects that won''t show???

Wow, that was a fast couple of replies! Thanks for yout time!

[QOUTE]Hi. Here are the answers to the questions I can answer.
1. Yes. Objecs are draw even when not visible.
1b Yes u can do it. goto http://www.gametutorials.com and look at the OpenGL tut on frustrum culling.
2. I have no idea what a phaser effect looks like so I can;''t hlp
3. Yea it can be done, but it is kind of hard if you are a real newbie. Once u get good enough with OGL, that effect should be nothing;
[/QOUTE]

Replies:
1. Pity, that would mean even more processor power! Thanks anyway! I will look at that site.

2. I think I can give some examples, a kinda similar effect (apart from the charging effect) is a laser beam or ion beam that you see in other games.

3. I tend to learn fast (did the basics of C++ under 2 houres), can you give me examples?

@ NorLeaf: I don''t want to render them, that is the point.



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quote:

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Original post by norleaf
Ok, I''m still pretty new at this, so I might be mistaken, but I thought clipping was not drawing objects, that would be visible if they weren''t blocked by another object closer to the camera (ie. a man standing behind a brick wall, doesn''t need to be rendered, because you obviously can''t see him without X-ray vision...;P)

What goes to objects behind the camera, I am thinking something like Anonymous Poster, but I''m not sure at all...

Either way: why would you want to render objects that won''t show???

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Clipping only removes objects not within the camera''s viewing frustum.

Objects which are behind something, are still drawn.The process of making the front object visible is called hidden surface removal. This is done by the Depth Buffering in OpenGL. Depth Buffering only decides which pixels should be infront in the case that there is more than 1 pixel at the same X Y coordinate.
However the object is still drawn and rendered.

Ok, more reading to do (octrees and Fustrum).
More questions:
4. Is there a maximum on the number of lights?

5. How do I make Omni Lights in OpenGL (or Direct X, I am giving the player the option of the 2)?
For the ones that don''t know what Omni light is, here is what I think that it is:
Omni light is like a spot light (or diffuse), but it is directed directly at the camera from a point, and when the angle is correct you see the omni effect as the flares on the projectiles on the following pictures (not by me):
http://021310061976.hypermart.net/images/pulse08.jpg
http://021310061976.hypermart.net/images/pulse01.jpg

This is the tutorial where it was discussed:
http://www.scifi-meshes.com/forums/showthread.php?s=&threadid=5666

Thanks (again) for your time,


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