Hi Rômulo,
Hi,
I have used normal mapping using GLSL and OSG for my application (an imaging
sonar simulation) and I got problems by calculating the TBN matrix on shaders.
The normal vectors contain lower resolution on border in comparison with the
center of image.
You cannot get a valid Co-TangentSpace by taking only the normal into
account considering arbitrary geometries. There are multiple ways to
tackle this however:
First is to calculate the mesh's tangentspace beforehand and pass the
tangent and binormal via vertex attributes.
See the osgUtil::TangentSpaceGenerator (example in the osg::CookBook
AFAIK).
Second one is to calculate it in the view-space. Beware of dragons,
since the precision will be awful for big coordinates:
http://www.thetenthplanet.de/archives/1180
hth
Sebastian
Follows my vertex code:
Code:
#version 130
out vec3 pos;
out vec3 normal;
out mat3 TBN;
void main() {
pos = (gl_ModelViewMatrix * gl_Vertex).xyz;
normal = gl_NormalMatrix * gl_Normal.xyz;
vec3 n = normalize(normal);
vec3 t = normalize(cross(normal, vec3(-1,0,0)));
vec3 b = cross(t, n) + cross(n, t);
TBN = transpose(mat3(t,b,n));
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
gl_TexCoord[0] = gl_MultiTexCoord0;
}
Part of my fragment code:
Code:
#version 130
in vec3 pos;
in vec3 normal;
in mat3 TBN;
uniform sampler2D normalTexture;
void main() {
vec3 newNormal = (texture2D(normalTexture, gl_TexCoord[0].st).rgb * 2.0 -
1) * TBN;
newNormal = normalize(newNormal);
...
}
The resulting figure is attached.
How can I calculate the TBN matrix to compute the normal mapping properly?
Thanks in advance,
...
Thank you!
Cheers,
Rômulo[/img]
------------------
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http://forum.openscenegraph.org/viewtopic.php?p=72324#72324
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