func (a *arrayBufferLayout) enable(c *opengl.Context, program opengl.Program) {
for _, p := range a.parts {
c.EnableVertexAttribArray(program, p.name)
}
total := a.totalBytes()
offset := 0
for _, p := range a.parts {
c.VertexAttribPointer(program, p.name, p.num, p.dataType, p.normalize, total, offset)
offset += p.dataType.SizeInBytes() * p.num
}
}