I'm trying to render a cube using an array of 8 vertices and an index-array of 24 (4*6) indices into the vertex array. But how can I specify per-face variables, like colors and normals without using deprecated functions? For this I need a separate set of indices, but when I specify two index-arrays (GL_ELEMENT_ARRAY_BUFFERs) and point them to different shader-variables (with two calls to glVertexAttribPointer) something goes wrong, and it doesn't render anything (but doesn't report any errors either - checked with glGetError). Do I have to use different calls to glDrawElements for each face, with color and normal loaded into uniform variables?
To clarify, the problem arises when each of the 8 vertices are part of different faces and need different values for color and normal.