#version 330 core layout (points) in; layout (line_strip, max_vertices = 2) out; uniform float t; void main() { gl_Position = gl_in[0].gl_Position + vec4(-0.1 + sin(t)*0.1, 0.0, 0.0, 0.0); EmitVertex(); gl_Position = gl_in[0].gl_Position + vec4( 0.1 - sin(t)*0.1, 0.0, 0.0, 0.0); EmitVertex(); EndPrimitive(); }