fixes

source/opengl/data/shader_program_data.cpp

@@ -0,0 +1,90 @@
+
+#include "opengl/data/shader_program_data.hpp"
+
+#include <fstream>
+#include "GL/glew.h"
+#include <glm/gtc/type_ptr.hpp>
+
+#include "util/for_each.hpp"
+#include "util/logger.hpp"
+#include "opengl/error.hpp"
+
+namespace zgl
+{
+
+std::error_code shader_program_data::build_from(
+	const shader_handle& vertex_shader,
+	const shader_handle& geometry_shader,
+	const shader_handle& fragment_shader,
+	shader_program_data& data
+) {
+	auto error = std::error_code{};
+
+	auto check_error = [&error, ec = static_cast<GLenum>(GL_NO_ERROR)]() mutable -> std::error_code&
+	{
+		ec = glGetError();
+		if (ec != GL_NO_ERROR) {
+			error = make_error_code(ec);
+		}
+		return error;
+	};
+
+	const auto program_id = glCreateProgram();
+	if (check_error()) return error;
+
+	using namespace std::string_view_literals;
+
+	constexpr auto shader_names = std::array{
+		"vertex"sv, "geometry"sv, "fragment"sv
+	};
+
+	for (const auto& [shader, name] : {
+		std::tie(vertex_shader, shader_names[0]),
+		std::tie(geometry_shader, shader_names[1]),
+		std::tie(fragment_shader, shader_names[2])
+	}) {
+		if (shader.shader_id) {
+			glAttachShader(program_id, shader.shader_id);
+		} else {
+			ztu::logger::warn("Using default % shader", name);
+		}
+	}
+
+	glLinkProgram(program_id);
+	if (check_error()) return error;
+
+	auto status = GLint{ GL_FALSE };
+	glGetProgramiv(program_id, GL_LINK_STATUS, &status);
+	if (check_error()) return error;
+
+	if (status == GL_FALSE) {
+		GLint log_length{};
+		glGetShaderiv(program_id, GL_INFO_LOG_LENGTH, &log_length);
+
+		auto log = std::string(log_length, ' ');
+		glGetProgramInfoLog(program_id, log_length, nullptr, log.data());
+
+		ztu::logger::warn("Error while linking program: [%] %", log_length, log);
+
+		return std::make_error_code(std::errc::io_error);
+	}
+
+
+	glUseProgram(0);
+
+	ztu::for_each::argument(
+		[&](const auto& shader)
+		{
+			if (shader.shader_id) {
+				glDetachShader(program_id, shader.shader_id);
+			}
+			return true;
+		},
+		vertex_shader, geometry_shader, fragment_shader
+	);
+
+	data = shader_program_data{ program_id };
+
+	return {};
+}
+}