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# gluontronic

Member Since 21 Jun 2012
Offline Last Active Jul 03 2012 01:30 AM

### Light sources lighting volumic matter?

26 June 2012 - 03:07 AM

Hi there,

I'd like to understand how this light diffusion effect is done
Each light seems to influence the "space"
It seems there is a kind of diffusion.
I firstly thought about a kind of open-cubes based grid with transparent faces but which would reflect or distort those lights or whatever.
Not sure.

Thought about fog too.

Would someone have some leads to dig this ?
Any kind of leads would be appreciate.

### Quaternion rotation VS Euler angles based rotation

23 June 2012 - 01:50 AM

Hi there,

If I use quaternion to rotate an object in my 3d space, I won't have any gimbal lock right?

I know about the efficiency around calculation (multiplications only and no trigo, less memory for storage etc) but wanted to be sure about the lock.

Especially, I'm calculating azimuth and elevation using the coordinates X & Z of the resulting vector of translation+rotation to camera space.
The atan2 have singularities and I wanted to know if I used quaternion I would "override" these singularities.

My maths seem rusty..
Any help would be appreciate

### Calculation of azimuth & elevation of objects relative to a camera

23 June 2012 - 01:44 AM

I have a camera quaternion (a,b,c,d) and a cam position (camX, camY, camZ)
I have an object with 3d coordinates (x,y,z)

I need to calculate azimuth, elevation of objects relatively to the cam view direction & plane.

First question
If I keep the object in center of my view (I mean, if I aim at it with my cam), even If I rotate the cam, translate it keeping the object in the center, I should have the same azimuth value, right ??
I don't have that.

Second question, the calculation.
I'm doing (object coordinates - cam position), in order to translate the object to the cam.
I'm taking the resulting coordinates and make the sandwich product with the quaternion and its conjugate.
(I followed this for the pseudo code :http://fr.wikipedia....ns_l&#39;espace)

Then, I have a vector result and I take X & Z component and calculate the atan2.
Does it seem right ?
any leads or explanation would help me a lot in my struggle

### What is this kind of matter ... fog ?

22 June 2012 - 10:25 AM

Hi there,

I'd like to understand how this light diffusion effect is done
Each light seems to influence the "space"
It seems there is a kind of diffusion.
I firstly thought about a kind of open-cubes based grid with transparent faces but which would reflect or distort those lights or whatever.
Not sure.

Thought about fog too.

Would someone have some leads to dig this ?
Any kind of leads would be appreciate.

### Some statements about my project

22 June 2012 - 10:00 AM

Hi there,
I tried a little presentation of myself here: http://www.gamedev.n...1-little-hello/

I wanted to describe a bit my project before posting some questions.

myUniverse is a 3d visual & sound environment for composition and performance.
It is all based on Max6 framework.
The basic idea is to explore relationship between space & time, between visuals & sounds.
I can instantiate objects in this 3d space. Each object have sounds & visuals properties.
The camera visit the space and experience sounds & visuals during the travel.
A core made using JAVA instantiated inside Max6 is the centralize way to store/load my maps (a map is a set of objects and their properties, plus some global context stuff like fog presence or not etc)

I'm at the point when I need to :
- consolidate the engine (view frustum culling based on azimuth/elevation/distance, improvement of azimuth, elevation & distance calculations..)
- finish the small gui which helps me to compose (= create, move objects, change their properties etc)
- design my set of objects

Beginning to post here, because it seems the appropriate place for me.
Feel free to tell me I should post elsewhere.

Best

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