Am 09.10.2013 10:58, schrieb michael kapelko:
Hi.
I've added rendering of the depth buffer of the scene to the depth
texture from the point of view of the main camera (not the light), but
it's always gray as seen here at the bottom left:
http://youtu.be/qTHWE5_ZPXQ
It only changes to black when I'm almost at the end of the scene. And
when I'm behind it, it's gray again.
That is perfectly normal, as the values in the depth buffer are not
linear but logarithmic.
So values with small distance to the near clipping plane take up much
more "digits" than those far away.
You should add a shader to the debug display to account for this.
Therefore you should pass near,far clipping plane values and
"renormalize" the displayed depth value.
I cannot give you the code snippet right now, as I don't have the
project here, but you should find it easily using google.
cheers
Sebastian
Here's my:
1) depth texture setup: http://goo.gl/plsc1U
2) RTT camera that writes to the depth texture: http://goo.gl/eYS6pC
3) display of the resulting depth texture: http://goo.gl/N5hUxb
What am I doing wrong?
Thanks.
2013/10/9 michael kapelko <[email protected] <mailto:[email protected]>>
Hi.
Thanks a lot! I totally missed vec4 position when I tried to use
only vec3 one with osg_ViewMatrixInverse.
2013/10/8 Marcel Pursche
<[email protected]
<mailto:[email protected]>>
Hi,
I don't know if you already found the solution to your
problem, but this is how you can calculate the camera position
in worldspace:
Code:
vec4 cameraPos_wordspace = osg_ViewMatrixInverse * vec4(0.0,
0.0, 0.0, 1.0);
The rotation and scale factors can be found in the first three
rows and columns of a matrix, so if you only want to compute a
rotation and scale it is sufficient to use a 3x3 matrix.
But to mathematically compute a translation of a vector you
need to use a 4x4 matrix. The vector needs to be expanded to
the 4th dimension, as-well to make it compatible with the
matrix for multiplication.
Here is how it works:
Code:
M * v = v'
<==>
1 0 0 tx * x = 1*x + 0*y + 0*z + tx * 1
0 1 0 ty * y = 0*x + 1*y + 0*z + ty * 1
0 0 1 tz * z = 0*x + 0*y + 1*z + tz * 1
0 0 0 1 * 1 = 0*x + 0*y + 0*z + 1*1
(These are the rows of a matrix not individual equations, I
wasn't able to format it in a good way, sorry)
no if we simplify this we get:
Code:
x+tx
= y+ty
z+tz
1
As we can see it all boils down to adding an offset the the
original vector. For the rest of your computations you can
just ignore the w component of the vector.
I hope I was able to shed some light on the dark ;)
Thank you!
Cheers,
Marcel
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=56677#56677
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