149 lines
3.7 KiB
C++
149 lines
3.7 KiB
C++
#ifndef INCLUDE_DYNAMIC_MODEL_DATA_IMPLEMENTATION
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# error Never include this file directly include 'dynamic_vertex_buffer.hpp'
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#endif
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#include "util/specialised_lambda.hpp"
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#include "opengl/type_utils.hpp"
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#include <cstring>
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#include <algorithm>
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#include <numeric>
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template<typename C, typename... Ts>
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C& dynamic_vertex_buffer<C, Ts...>::components()
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{
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return m_components;
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}
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template<typename C, typename... Ts>
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const C& dynamic_vertex_buffer<C, Ts...>::components() const
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{
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return m_components;
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}
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template <typename T>
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concept numeric_type = std::integral<T> or std::floating_point<T>;
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template<typename C, typename... Ts>
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void dynamic_vertex_buffer<C, Ts...>::build_vertex_buffer(
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std::vector<ztu::u8>& vertex_buffer,
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std::size_t& component_count,
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std::array<GLenum, sizeof...(Ts)>& component_types,
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std::array<GLint, sizeof...(Ts)>& component_lengths,
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GLsizei& stride
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) const {
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const auto for_all_components = [&]<typename T>(auto&& f, const T default_value)
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{
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return std::apply(
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[&](const auto&... component_buffer)
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{
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std::array<T, sizeof...(component_buffer)> results{};
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auto i = std::size_t{};
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(
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(
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results[i] = [&](const auto& buffer, const auto index) -> T
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{
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if ((m_components & C{ 1 << index }) != C{})
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{
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return f(buffer, index);
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}
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return default_value;
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}(component_buffer, i),
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++i
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),
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...
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);
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return results;
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},
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m_component_buffers
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);
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};
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component_count = 0;
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component_types = for_all_components(
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ztu::specialised_lambda
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{
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[&component_count]<numeric_type Component, std::size_t Count>(const std::vector<std::array<Component, Count>>&, std::size_t)
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{
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++component_count;
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return zgl::type_utils::to_gl_type<Component>();
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},
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[&component_count]<numeric_type Component>(const std::vector<Component>&, std::size_t)
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{
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++component_count;
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return zgl::type_utils::to_gl_type<Component>();
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}
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},
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GLenum{ GL_INVALID_VALUE }
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);
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const auto element_counts = for_all_components(
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[]<class Component>(const std::vector<Component>& buffer, std::size_t)
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{
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return buffer.size();
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},
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std::numeric_limits<std::size_t>::max()
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);
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const auto minimum_element_count = std::ranges::min(element_counts);
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component_lengths = for_all_components(
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ztu::specialised_lambda
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{
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[]<class Component>(const std::vector<Component>&, std::size_t)
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{
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return 1;
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},
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[]<class Component, std::size_t Count>(const std::vector<std::array<Component, Count>>&, std::size_t)
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{
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return Count;
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}
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},
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GLsizei{ 0 }
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);
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auto component_sizes = std::array<GLsizei, sizeof...(Ts)>{};
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for (std::size_t i{}; i != component_sizes.size(); ++i)
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{
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component_sizes[i] = component_lengths[i] * zgl::type_utils::size_of(component_types[i]);
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}
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const auto total_size = minimum_element_count * std::accumulate(
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component_sizes.begin(),
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component_sizes.end(),
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GLsizei{ 0 }
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);
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vertex_buffer.resize(total_size);
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// Calculate offsets and stride
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auto component_offsets = component_sizes;
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stride = 0;
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for (std::size_t i{}; i != component_offsets.size(); ++i) {
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component_offsets[i] = stride;
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stride += component_sizes[i];
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}
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// Copy all the components over one by one
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for_all_components(
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[&]<class Component>(const std::vector<Component>& buffer, std::size_t index)
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{
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std::size_t pos = component_offsets[index];
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for (std::size_t i{}; i != minimum_element_count; ++i)
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{
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std::memcpy(
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&vertex_buffer[pos],
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buffer[i].data(),
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component_sizes[index]
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);
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pos += stride;
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}
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return 0;
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},
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0
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);
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// remove values of unused components
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std::ignore = std::ranges::remove(component_lengths, 0);
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std::ignore = std::ranges::remove(component_types, GL_INVALID_VALUE);
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}
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