opengl - Can I make color data not render as gradient?

I would like for the color between my vertices to not be rendered as a gradient, but as a hard break. Is there any way to accomplish this in OpenGL/GLSL?

Answer

You can try doing this with flat attribute qualifier in shaders, like so:

flat vec3 surfColor;

It tells GLSL to pass values from vertex to fragment without interpolation.

From GLSL Interpolation qualifiers:

Interpolation qualifiers control how interpolation of values happens across a triangle or other primitive. There are three basic interpolation qualifiers.

flat​ The value will not be interpolated. The value given to the fragment shader is the value from the Provoking Vertex for that primitive.
...

Additional read on SO: https://stackoverflow.com/questions/27581271/flat-qualifier-in-glsl