In opengl es 2, is there a way to prevent interpolation of varyings

Question

In other words, emulating the old opengl flat shading model, so you could for example have a line strip where each segment is a distinct color rather than an interpolation of color across the segment?

Answer 1

Not directly. GLSL for Desktop has the flat keyword, but GLSL ES doesn't have it (it's reserved). A trick to emulate this behaviour is to assign the same color at each vertex in a triangle (or in a segment), so the interpolation is between the same value.