// useVertexAttribArrays will enable the vertex attrib array for the flags passed
// and if the flags were not passed it will disabled them. This make sure that only
// those attributes are enabled.
func useVertexAttribArrays(arraybits uint32) {
diff := arraybits ^ gl_state.enabledAttribArrays
if diff == 0 {
return
}
// Max 32 attributes. As of when this was written, no GL driver exposes more
// than 32. Lets hope that doesn't change...
for i := uint32(0); i < 32; i++ {
bit := uint32(1 << i)
if (diff & bit) > 0 {
if (arraybits & bit) > 0 {
gl.EnableVertexAttribArray(gl.Attrib{Value: uint(i)})
} else {
gl.DisableVertexAttribArray(gl.Attrib{Value: uint(i)})
}
}
}
gl_state.enabledAttribArrays = arraybits
// glDisableVertexAttribArray will make the constant value for a vertex
// attribute undefined. We rely on the per-vertex color attribute being
// white when no per-vertex color is used, so we set it here.
// FIXME: Is there a better place to do this?
if (diff&attribflag_color) > 0 && (arraybits&attribflag_color) == 0 {
gl.VertexAttrib4f(attrib_color, 1.0, 1.0, 1.0, 1.0)
}
}
// SetColorC will sets the color used for drawing.
func SetColorC(c *Color) {
states.back().color = c
gl.VertexAttrib4f(attrib_constantcolor, c[0], c[1], c[2], c[3])
}