prog_var_loc.hpp

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#ifndef OGLPLUS_GL_API_PROG_VAR_LOC_HPP
#define OGLPLUS_GL_API_PROG_VAR_LOC_HPP
 
#include "config.hpp"
#include <eagine/identifier.hpp>
 
namespace eagine::oglp {
//------------------------------------------------------------------------------
template <identifier_t TagId>
class prog_var_location {
    using int_type = gl_types::int_type;
    using uint_type = gl_types::uint_type;
 
public:
    constexpr prog_var_location() noexcept = default;
 
    explicit constexpr prog_var_location(int_type init) noexcept
      : _location{init} {}
 
    auto is_active() const noexcept -> bool {
        return _location >= 0;
    }
 
    explicit constexpr operator bool() const noexcept {
        return is_active();
    }
 
    constexpr auto location() const noexcept -> int_type {
        return _location;
    }
 
    constexpr auto index() const noexcept -> uint_type {
        if(_location < 0) {
#ifdef GL_INVALID_INDEX
            return GL_INVALID_INDEX;
#endif
        }
        return uint_type(_location);
    }
 
    explicit constexpr operator int_type() const noexcept {
        return _location;
    }
 
    friend constexpr auto
    operator==(prog_var_location a, prog_var_location b) noexcept {
        return a._location == b._location;
    }
 
    friend constexpr auto
    operator!=(prog_var_location a, prog_var_location b) noexcept {
        return a._location != b._location;
    }
 
    friend constexpr auto
    operator<(prog_var_location a, prog_var_location b) noexcept {
        return a._location < b._location;
    }
 
private:
    int_type _location{-1};
};
//------------------------------------------------------------------------------
using program_resource_location = prog_var_location<EAGINE_ID_V(Resource)>;
 
using vertex_attrib_location = prog_var_location<EAGINE_ID_V(VertexAttr)>;
 
using uniform_location = prog_var_location<EAGINE_ID_V(Uniform)>;
 
using subroutine_uniform_location = prog_var_location<EAGINE_ID_V(SubrtUnfrm)>;
 
using subroutine_location = prog_var_location<EAGINE_ID_V(Subroutine)>;
 
using frag_data_location = prog_var_location<EAGINE_ID_V(FragData)>;
 
using uniform_block_index = prog_var_location<EAGINE_ID_V(UniformBlk)>;
 
using shader_storage_block_index = prog_var_location<EAGINE_ID_V(ShdrStrBlk)>;
//------------------------------------------------------------------------------
} // namespace eagine::oglp
 
#endif // OGLPLUS_GL_API_PROG_VAR_LOC_HPP