The question is very simple.
How can I do the same thing (example from internet):
glBegin(GL_TRIANGLES);             // Begin Drawing Triangles

 glColor3f(1.0f,0.0f,0.0f);       // Set The Color To Red
 glVertex3f( 0.0f, 1.0f, 0.0f);   // Move Up One Unit From Center
(Top Point)

 glColor3f(0.0f,1.0f,0.0f);       // Set The Color To Green
 glVertex3f(-1.0f,-1.0f, 0.0f);   // Left And Down One Unit (Bottom
Left)

 glColor3f(0.0f,0.0f,1.0f);       // Set The Color To Blue
 glVertex3f( 1.0f,-1.0f, 0.0f);   // Right And Down One Unit (Bottom
Right)

glEnd();

with WPF?
There are some possibilities to use GradientBrush (with 'Stops'), but
how I can interpolate color between some (random created) points?

Many thanks in advice.

--Alex--