layout(vertices=3) out; in vec4 fca[]; out vec4 fct[]; void main(){ int tesslv = 4; gl_TessLevelOuter[0] = tesslv; gl_TessLevelOuter[1] = tesslv; gl_TessLevelOuter[2] = tesslv; gl_TessLevelInner[0] = tesslv; gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position; // Possible to use synchronization fct[gl_InvocationID] = fca[gl_InvocationID]; }