LineDrawable color by vertex

[miles-tbe]

Hello,

How would I go about trying to use a LineDrawable to make a line with different sections having different colors? Say I have 20 points and each 5 point section I need to be a different color? I currently have some code that uses this format:

LineDrawable* LineDrawn = new LineDrawable;

DrawnLine->setLineSmooth (true);
DrawnLine->setColor (osg::Vec4 (1, 0, 1, 1));
DrawnLine->pushVertex (osg::Vec3 (0, 0, 0));
DrawnLine->pushVertex (osg::Vec3 (10, 0, 20));
DrawnLine->dirty ();

I understand that setColor has an overload that allows for an index to be used (int index, osg::Vec4), but in practice I was unable to get it to work. I if I tried to add 2 more vertices and wanted them to be a different color, how would I do that?

Thanks,
Miles

[gwaldron]

You can use void setColor(unsigned i, const osg::Vec4& color) to set the color at a specific index.

Another way of building the line would be something like...

line->allocate(total_num_verts);
for(int i=0; i<total_num_verts; ++i) {
    line->setVertex(i, value);
    line->setColor(i, color);
    ....
}

Hope this helps!

[miles-tbe]

This did help. I realize what I was doing wrong now. I had this:

DrawnLine->setColor (color1);
DrawnLine->pushVertex (vert1);
DrawnLine->pushVertex (vert2);
DrawnLine->setColor (2, color2);
DrawnLine->pushVertex (vert3);
DrawnLine->pushVertex (vert4);

I was trying to access a vertex index that had yet to be created. Got it working fine now. Thanks!