Add Wavefront OBJ file parser

libs/gfx/include/psemek/gfx/obj_parser.hpp

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <psemek/geom/vector.hpp>
+#include <psemek/geom/point.hpp>
+#include <psemek/geom/simplex.hpp>
+
+#include <iostream>
+#include <vector>
+
+namespace psemek::gfx
+{
+
+	struct obj_data
+	{
+		struct vertex
+		{
+			geom::point<float, 3> position;
+			geom::vector<float, 2> texcoord;
+			geom::vector<float, 3> normal;
+		};
+
+		std::vector<geom::triangle<vertex>> triangles;
+	};
+
+	obj_data parse_obj(std::istream & is);
+
+}

libs/gfx/source/obj_parser.cpp

@@ -0,0 +1,99 @@
+#include <psemek/gfx/obj_parser.hpp>
+#include <psemek/util/to_string.hpp>
+
+#include <string>
+#include <sstream>
+#include <stdexcept>
+
+namespace psemek::gfx
+{
+
+	obj_data parse_obj(std::istream & is)
+	{
+		std::vector<geom::point<float, 3>> positions;
+		std::vector<geom::vector<float, 2>> texcoords;
+		std::vector<geom::vector<float, 3>> normals;
+
+		obj_data result;
+
+		std::string line;
+		std::size_t line_count = 0;
+
+		auto fail = [&](auto const & ... args){
+			throw std::runtime_error(util::to_string("Error parsing OBJ data, line ", line_count, ": ", args...));
+		};
+
+		while (std::getline(is >> std::ws, line))
+		{
+			++line_count;
+
+			if (line.empty()) continue;
+
+			if (line[0] == '#') continue;
+
+			std::istringstream ls(std::move(line));
+
+			std::string tag;
+			ls >> tag;
+
+			if (tag == "v")
+			{
+				auto & p = positions.emplace_back();
+				ls >> p[0] >> p[1] >> p[2];
+			}
+			else if (tag == "vt")
+			{
+				auto & t = texcoords.emplace_back();
+				ls >> t[0] >> t[1];
+			}
+			else if (tag == "vn")
+			{
+				auto & n = normals.emplace_back();
+				ls >> n[0] >> n[1] >> n[2];
+			}
+			else if (tag == "f")
+			{
+				std::vector<obj_data::vertex> vertices;
+
+				while (ls)
+				{
+					std::size_t ip, it, in;
+					ls >> ip;
+					if (ls.eof()) break;
+					if (!ls || ls.get() != '/')
+						fail("expected '/'");
+					ls >> it;
+					if (!ls || ls.get() != '/')
+						fail("expected '/'");
+					ls >> in;
+
+					--ip;
+					--it;
+					--in;
+
+					if (ip >= positions.size())
+						fail("bad position index (", ip, ")");
+
+					if (it >= texcoords.size())
+						fail("bad texcoord index (", ip, ")");
+
+					if (in >= normals.size())
+						fail("bad normal index (", ip, ")");
+
+					auto & v = vertices.emplace_back();
+					v.position = positions[ip];
+					v.texcoord = texcoords[it];
+					v.normal = normals[in];
+				}
+
+				for (std::size_t i = 1; i + 1 < vertices.size(); ++i)
+				{
+					result.triangles.push_back({{vertices[0], vertices[i], vertices[i + 1]}});
+				}
+			}
+		}
+
+		return result;
+	}
+
+}