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#pragma once
#include <mbgl/gl/shader.hpp>
#include <mbgl/util/optional.hpp>
#include <array>
#include <functional>
#include <tuple>
namespace mbgl {
namespace gl {
template <class T>
void bindUniform(UniformLocation, const T&);
template <class Tag, class T>
class UniformValue {
public:
explicit UniformValue(T t_) : t(std::move(t_)) {}
T t;
};
template <class Tag, class T>
class Uniform {
public:
using Value = UniformValue<Tag, T>;
class State {
public:
State(const char* name, const Shader& shader)
: location(shader.getUniformLocation(name)) {}
void operator=(const Value& value) {
if (!current || *current != value.t) {
current = value.t;
bindUniform(location, value.t);
}
}
private:
optional<T> current;
UniformLocation location;
};
};
template <class Tag, class T>
using UniformScalar = Uniform<Tag, T>;
template <class Tag, class T, size_t N>
using UniformVector = Uniform<Tag, std::array<T, N>>;
template <class Tag, class T, size_t N>
using UniformMatrix = Uniform<Tag, std::array<T, N*N>>;
#define MBGL_DEFINE_UNIFORM_SCALAR(type_, name_) \
struct name_ : ::mbgl::gl::UniformScalar<name_, type_> { static constexpr auto name = #name_; }
#define MBGL_DEFINE_UNIFORM_VECTOR(type_, n_, name_) \
struct name_ : ::mbgl::gl::UniformVector<name_, type_, n_> { static constexpr auto name = #name_; }
#define MBGL_DEFINE_UNIFORM_MATRIX(type_, n_, name_) \
struct name_ : ::mbgl::gl::UniformMatrix<name_, type_, n_> { static constexpr auto name = #name_; }
template <class... Us>
class Uniforms {
public:
using State = std::tuple<typename Us::State...>;
using Values = std::tuple<typename Us::Value...>;
static State state(const Shader& shader) {
return State { { Us::name, shader }... };
}
static std::function<void ()> binder(State& state, Values&& values_) {
return [&state, values = std::move(values_)] () mutable {
noop((std::get<typename Us::State>(state) = std::get<typename Us::Value>(values), 0)...);
};
}
private:
// This exists only to provide a varags context for unpacking the assignments in `binder`.
template <int...> static void noop(int...) {}
};
} // namespace gl
} // namespace mbgl
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