Re: [osg-users] How to use vertex attributes?

[John Kelso]

I have learned to avoid numbers 0, 2, 3 and 8.

See http://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg26406.html

John

On Tue, 12 Jan 2010, Andrew Holland wrote:

Hi,

I want to use vertex attributes and I'm having trouble getting it to work. I 
think the problem should lie within this code here:


Code:

program->addBindAttribLocation("a_col", 0);

osg::Vec4Array* colors = new osg::Vec4Array;

for(int i=0;i<model->verticesNum;i++) {
        float r = model->cols[i*4];
        float g = model->cols[i*4+1];
        float b = model->cols[i*4+2];
        float a = model->cols[i*4+3];
        colors->push_back(osg::Vec4(r,g,b,a));
}


//for this commented out code, when used with gl_Color in the vertex shader, it 
works, displaying the mesh and colours properly.
//pyramidGeometry->setColorArray(colors);
//pyramidGeometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);

//but using this code with the a_col atttribute instead of the gl_Color
//doesn't work, it shows the mesh to be white, and slightly deformed. e.g. 
vertices being out of place
pyramidGeometry->setVertexAttribArray(0, colors);
pyramidGeometry->setVertexAttribBinding(0, osg::Geometry::BIND_PER_VERTEX);





Am I missing something here?

I'll post the whole code below, incase the above code isn't enough.

..omitted, forums says something about urls and 2 posts, don't know why..


Also my shader programs are:

vertex shader

Code:



attribute vec4 a_col;
varying vec4 col;

void main() {
        col = a_col;//gl_Color;
        gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;

}




fragment shader

Code:

varying vec4 col;

void main() {
        gl_FragColor =col;
}




Thanks!

andrew

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=22452#22452





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