Re: [osg-users] texture mapping to trapezoid
Hi,
Thanks for all the replies. My problem was solved by applying some sort of
perspective correction to my texture coordinates.
While creating the geometry I supplied a Vec3Array instead of a Vec2Array as
tex coord array. The tex coords that stay on short edge of the trapezoid, get a
z value of (len_short_edge / len_long_edge) whereas the the other tex coords
got 1.
Before sampling, the fragment shader divided the incoming tex coord vector by
its z. (In order to obtain a texture coordinate whose z is always 1).
I changed:
osg::Vec2Array *t = new osg::Vec2Array;
t->push_back(osg::Vec2(0, 0));
t->push_back(osg::Vec2(0, 1));
t->push_back(osg::Vec2(1, 1));
t->push_back(osg::Vec2(1, 0));
geom->setTexCoordArray(0, t);
to:
osg::Vec3Array *t = new osg::Vec3Array;
t->push_back(osg::Vec3(0, 0, 1));
t->push_back(osg::Vec3(0, 0.33f, 0.33f));
t->push_back(osg::Vec3(0.33f, 0.33f, 0.33f));
t->push_back(osg::Vec3(1, 0, 1));
geom->setTexCoordArray(0, t);
and used the following fragment shader:
uniform sampler2D sampler;
void main()
{
vec3 texCoord = gl_TexCoord[0];
gl_FragColor = texture2D(sampler, texCoord / texCoord.z);
}
Have a nice day,
Can
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Re: [osg-users] texture mapping to trapezoid
Hi Shayne, Thank you for the quick response :) A screen shot of quad is available here: http://img36.imageshack.us/img36/5741/problem2009052217560820.jpg I left my texture attributes as default. Also didn't change anything at a parent stateset (in other words, i gave the node returned by createBillboard() directly to osgViewer::setSceneData) my texture is a 256x256 bmp file which is available here: http://img40.imageshack.us/img40/981/spot.png Thanks, Can -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=12768#12768 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] texture mapping to trapezoid
Hi, I 'm having trouble mapping a texture2d to a quad. The texture looks correct when the quad is rectangle/square shaped, but incorrect when it is trapezoid shaped. I'm using the following code to create the geometry: http://pastebin.com/m47ba3f47 How can i fix it so that the texture looks correct (as if it was squeezed at the top and stretched at the bottom) Thank you! Cheers, Can -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=12760#12760 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
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Hi, I'm writing a simple nodevisitor to compute the lightmap of a given node. This nodevisitor treats transforms and geodes specially, so that each vertex in the geometry is multiplied with the most recent transform matrix in order to obtain world coordinates. So far the above code works well except that i don't know how to transform the normals. Can I obtain the normal matrix directly from the transformation matrix, if so how? Thank you, Can -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=8857#8857 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
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