Cube vertex shader - usage: glDrawArrays(GL_TRIANGLES, 0, 36), disable all vertex arrays

cube.glslv

#version 420

uniform mat4 projection_matrix;
uniform mat4 model_matrix;

void main()
{
    int tri = gl_VertexID / 3;
    int idx = gl_VertexID % 3;
    int face = tri / 2;
    int top = tri % 2;

    int dir = face % 3;
    int pos = face / 3;

    int nz = dir >> 1;
    int ny = dir & 1;
    int nx = 1 ^ (ny | nz);

    vec3 d = vec3(nx, ny, nz);
    float flip = 1 - 2 * pos;

    vec3 n = flip * d;
    vec3 u = -d.yzx;
    vec3 v = flip * d.zxy;

    float mirror = -1 + 2 * top;
    vec3 xyz = n + mirror*(1-2*(idx&1))*u + mirror*(1-2*(idx>>1))*v;

    gl_Position = projection_matrix * model_matrix * vec4(xyz, 1.0);
}