| Computers Forum Index » Computer - Graphics - API (Opengl) » extract obserwator position from modelview matrix... |
|
Page 1 of 1 |
|
| Author |
Message |
| Michal... |
 Posted: Mon Aug 31, 2009 8:03 pm |
|
|
|
Guest
|
How could i extract obserwator position from modelview matrix?
I tried to do it like this:
double m[16];
glGetDoublev(GL_MODELVIEW_MATRIX, m)
double x = m[12];
double y = m[13];
double z = m[14];
but it looks like it is not observator position.
-- |
|
|
| Back to top |
|
|
|
| fungus... |
| Posted: Mon Aug 31, 2009 8:03 pm |
|
|
|
Guest
|
On Aug 31, 6:03 pm, Michal <natural-born-kil... at (no spam) dontmailme.com> wrote:
Quote: How could i extract obserwator position from modelview matrix?
I tried to do it like this:
double m[16];
glGetDoublev(GL_MODELVIEW_MATRIX, m)
double x = m[12];
double y = m[13];
double z = m[14];
but it looks like it is not observator position.
You must invert the matrix first.
--
<\___/>
/ O O \
\_____/ FTB.
http://www.topaz3d.com/ - New 3D editor for real time simulation |
|
|
| Back to top |
|
|
|
| fungus... |
| Posted: Mon Aug 31, 2009 9:51 pm |
|
|
|
Guest
|
On Aug 31, 9:43 pm, Michal <natural-born-kil... at (no spam) dontmailme.com> wrote:
Quote:
You must invert the matrix first.
does this matrix has some properties that could help me do it or do i
have to use generic methods?
If there's no scale factor in the matrix then this
should work:
x = -(m[12]*m[0] + m[13]*m[1] + m[14]*m[2]);
y = -(m[12]*m[4] + m[13]*m[5] + m[14]*m[6]);
z = -(m[12]*m[8] + m[13]*m[9] + m[14]*m[10]);
If there's a scale factor you have to use generic methods.
--
<\___/>
/ O O \
\_____/ FTB.
http://www.topaz3d.com/ - New 3D editor for real time simulation |
|
|
| Back to top |
|
|
|
| Michal... |
| Posted: Mon Aug 31, 2009 11:43 pm |
|
|
|
Guest
|
On Mon, 31 Aug 2009 12:29:48 -0700 (PDT)
fungus <openglMYSOCKS at (no spam) artlum.com> wrote:
Quote: On Aug 31, 6:03 pm, Michal <natural-born-kil... at (no spam) dontmailme.com> wrote:
How could i extract obserwator position from modelview matrix?
I tried to do it like this:
double m[16];
glGetDoublev(GL_MODELVIEW_MATRIX, m)
double x = m[12];
double y = m[13];
double z = m[14];
but it looks like it is not observator position.
You must invert the matrix first.
does this matrix has some properties that could help me do it or do i
have to use generic methods? |
|
|
| Back to top |
|
|
|
| Michal... |
| Posted: Tue Sep 01, 2009 12:50 am |
|
|
|
Guest
|
Quote:
You must invert the matrix first.
or maybe there is some easier way to extract this position? Maybe glu
library has this functionality?
-- |
|
|
| Back to top |
|
|
|
| Wojciech \"Spook\" Sura... |
| Posted: Tue Sep 01, 2009 9:31 am |
|
|
|
Guest
|
Michal wrote:
Quote: How could i extract obserwator position from modelview matrix?
I tried to do it like this:
double m[16];
glGetDoublev(GL_MODELVIEW_MATRIX, m)
double x = m[12];
double y = m[13];
double z = m[14];
but it looks like it is not observator position.
Vector (0,0,0,1) multiplied by the modelview matrix sholud return inverse of
observer position (-Vector).
Best regards -- Spook. |
|
|
| Back to top |
|
|
|
|
