Hi,

   Finally I found where causes the problem.  For some reasons, gl_Vertex is 
not normalized.  I looked at osg shader source code (src\osgVolume\Shaders).  
For example, in file volume_frag.cpp, 

vec4 t0 = vertexPos;
vec4 te = cameraPos;

// by default te did to check the range (0 and 1), but t0 did not.
// If I added  some codes to check the range, then the problem is completed 
gone.

if (t0.x<0.0) t0.x = 0.0; if (t0.x>1.0) t0.x = 1.0; 
if (t0.y<0.0) t0.y = 0.0; if (t0.y>1.0) t0.y = 1.0; 
f (t0.z<0.0) t0.z = 0.0; if (t0.z>1.0) t0.z = 1.0; 


I believe the problem is related to GLSL version and latest Intel HD Graphics 
driver is using higher version of GLSL, but gl_Vertex does not normalize or the 
value is just over 1 or less then 0 (eg. 1.00001).  Then it causes the crash 
when running the sampling loop.  I am not an expert on GLSL, so I would like to 
confirm the best solution to handle this problem. Thanks.


Regards,
Clement Chu

________________________________________
From: osg-users <[email protected]> on behalf of 
[email protected] <[email protected]>
Sent: Wednesday, 30 August 2017 17:31
To: [email protected]
Subject: [ExternalEmail] [osg-users] RayTracedTechnique hangs with Intel HD 
Graphics

Hi,

   My program uses RayTracedTechnique for volume rendering, but it hangs with 
Intel HD graphics 520, 530 and 620. My old laptop works fine which is using 
Intel HD Graphic 3000.  Other machines with Nvidia cards are working fine too.  
I believe the problem is on shaders in the sampling loop.  My program is using 
osg 3.2.3.  I also tried to upgrade to osg 3.4.1, but the same problem occurred 
with Intel HD Graphic 520, 530 and 620.  Do anyone have similar problem and any 
solution to fix it?  Many thanks.


Regards,
Clement Chu
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