Initial commit

Stripped back and formatted from https://github.com/BennyQBD/ModernOpenGLTutorial/

1 files changed, 396 insertions, 0 deletions

diff --git a/obj_loader.cpp b/obj_loader.cpp
new file mode 100644
index 0000000..b3cb517
--- /dev/null
+++ b/obj_loader.cpp
@@ -0,0 +1,396 @@
+#include "obj_loader.h"
+#include <algorithm>
+#include <fstream>
+#include <iostream>
+#include <map>
+
+static bool CompareOBJIndexPtr(const OBJIndex * a, const OBJIndex * b);
+static inline unsigned int FindNextChar(unsigned int start, const char * str, unsigned int length, char token);
+static inline unsigned int ParseOBJIndexValue(const std::string & token, unsigned int start, unsigned int end);
+static inline float ParseOBJFloatValue(const std::string & token, unsigned int start, unsigned int end);
+static inline std::vector<std::string> SplitString(const std::string & s, char delim);
+
+OBJModel::OBJModel(const std::string & fileName)
+{
+	hasUVs = false;
+	hasNormals = false;
+	std::ifstream file;
+	file.open(fileName.c_str());
+
+	std::string line;
+	if (file.is_open()) {
+		while (file.good()) {
+			getline(file, line);
+
+			unsigned int lineLength = line.length();
+
+			if (lineLength < 2)
+				continue;
+
+			const char * lineCStr = line.c_str();
+
+			switch (lineCStr[0]) {
+				case 'v':
+					if (lineCStr[1] == 't')
+						this->uvs.push_back(ParseOBJVec2(line));
+					else if (lineCStr[1] == 'n')
+						this->normals.push_back(ParseOBJVec3(line));
+					else if (lineCStr[1] == ' ' || lineCStr[1] == '\t')
+						this->vertices.push_back(ParseOBJVec3(line));
+					break;
+				case 'f':
+					CreateOBJFace(line);
+					break;
+				default:
+					break;
+			};
+		}
+	}
+	else {
+		std::cerr << "Unable to load mesh: " << fileName << std::endl;
+	}
+}
+
+void
+IndexedModel::CalcNormals()
+{
+	for (unsigned int i = 0; i < indices.size(); i += 3) {
+		int i0 = indices[i];
+		int i1 = indices[i + 1];
+		int i2 = indices[i + 2];
+
+		glm::vec3 v1 = positions[i1] - positions[i0];
+		glm::vec3 v2 = positions[i2] - positions[i0];
+
+		glm::vec3 normal = glm::normalize(glm::cross(v1, v2));
+
+		normals[i0] += normal;
+		normals[i1] += normal;
+		normals[i2] += normal;
+	}
+
+	for (unsigned int i = 0; i < positions.size(); i++)
+		normals[i] = glm::normalize(normals[i]);
+}
+
+IndexedModel
+OBJModel::ToIndexedModel()
+{
+	IndexedModel result;
+	IndexedModel normalModel;
+
+	unsigned int numIndices = OBJIndices.size();
+
+	std::vector<OBJIndex *> indexLookup;
+
+	for (unsigned int i = 0; i < numIndices; i++)
+		indexLookup.push_back(&OBJIndices[i]);
+
+	std::sort(indexLookup.begin(), indexLookup.end(), CompareOBJIndexPtr);
+
+	std::map<OBJIndex, unsigned int> normalModelIndexMap;
+	std::map<unsigned int, unsigned int> indexMap;
+
+	for (unsigned int i = 0; i < numIndices; i++) {
+		OBJIndex * currentIndex = &OBJIndices[i];
+
+		glm::vec3 currentPosition = vertices[currentIndex->vertexIndex];
+		glm::vec2 currentTexCoord;
+		glm::vec3 currentNormal;
+
+		if (hasUVs)
+			currentTexCoord = uvs[currentIndex->uvIndex];
+		else
+			currentTexCoord = glm::vec2(0, 0);
+
+		if (hasNormals)
+			currentNormal = normals[currentIndex->normalIndex];
+		else
+			currentNormal = glm::vec3(0, 0, 0);
+
+		unsigned int normalModelIndex;
+		unsigned int resultModelIndex;
+
+		// Create model to properly generate normals on
+		std::map<OBJIndex, unsigned int>::iterator it = normalModelIndexMap.find(*currentIndex);
+		if (it == normalModelIndexMap.end()) {
+			normalModelIndex = normalModel.positions.size();
+
+			normalModelIndexMap.insert(std::pair<OBJIndex, unsigned int>(*currentIndex, normalModelIndex));
+			normalModel.positions.push_back(currentPosition);
+			normalModel.texCoords.push_back(currentTexCoord);
+			normalModel.normals.push_back(currentNormal);
+		}
+		else
+			normalModelIndex = it->second;
+
+		// Create model which properly separates texture coordinates
+		unsigned int previousVertexLocation = FindLastVertexIndex(indexLookup, currentIndex, result);
+
+		if (previousVertexLocation == (unsigned int)-1) {
+			resultModelIndex = result.positions.size();
+
+			result.positions.push_back(currentPosition);
+			result.texCoords.push_back(currentTexCoord);
+			result.normals.push_back(currentNormal);
+		}
+		else
+			resultModelIndex = previousVertexLocation;
+
+		normalModel.indices.push_back(normalModelIndex);
+		result.indices.push_back(resultModelIndex);
+		indexMap.insert(std::pair<unsigned int, unsigned int>(resultModelIndex, normalModelIndex));
+	}
+
+	if (!hasNormals) {
+		normalModel.CalcNormals();
+
+		for (unsigned int i = 0; i < result.positions.size(); i++)
+			result.normals[i] = normalModel.normals[indexMap[i]];
+	}
+
+	return result;
+};
+
+unsigned int
+OBJModel::FindLastVertexIndex(
+		const std::vector<OBJIndex *> & indexLookup, const OBJIndex * currentIndex, const IndexedModel & result)
+{
+	unsigned int start = 0;
+	unsigned int end = indexLookup.size();
+	unsigned int current = (end - start) / 2 + start;
+	unsigned int previous = start;
+
+	while (current != previous) {
+		OBJIndex * testIndex = indexLookup[current];
+
+		if (testIndex->vertexIndex == currentIndex->vertexIndex) {
+			unsigned int countStart = current;
+
+			for (unsigned int i = 0; i < current; i++) {
+				OBJIndex * possibleIndex = indexLookup[current - i];
+
+				if (possibleIndex == currentIndex)
+					continue;
+
+				if (possibleIndex->vertexIndex != currentIndex->vertexIndex)
+					break;
+
+				countStart--;
+			}
+
+			for (unsigned int i = countStart; i < indexLookup.size() - countStart; i++) {
+				OBJIndex * possibleIndex = indexLookup[current + i];
+
+				if (possibleIndex == currentIndex)
+					continue;
+
+				if (possibleIndex->vertexIndex != currentIndex->vertexIndex)
+					break;
+				else if ((!hasUVs || possibleIndex->uvIndex == currentIndex->uvIndex)
+						&& (!hasNormals || possibleIndex->normalIndex == currentIndex->normalIndex)) {
+					glm::vec3 currentPosition = vertices[currentIndex->vertexIndex];
+					glm::vec2 currentTexCoord;
+					glm::vec3 currentNormal;
+
+					if (hasUVs)
+						currentTexCoord = uvs[currentIndex->uvIndex];
+					else
+						currentTexCoord = glm::vec2(0, 0);
+
+					if (hasNormals)
+						currentNormal = normals[currentIndex->normalIndex];
+					else
+						currentNormal = glm::vec3(0, 0, 0);
+
+					for (unsigned int j = 0; j < result.positions.size(); j++) {
+						if (currentPosition == result.positions[j]
+								&& ((!hasUVs || currentTexCoord == result.texCoords[j])
+										&& (!hasNormals || currentNormal == result.normals[j]))) {
+							return j;
+						}
+					}
+				}
+			}
+
+			return -1;
+		}
+		else {
+			if (testIndex->vertexIndex < currentIndex->vertexIndex)
+				start = current;
+			else
+				end = current;
+		}
+
+		previous = current;
+		current = (end - start) / 2 + start;
+	}
+
+	return -1;
+}
+
+void
+OBJModel::CreateOBJFace(const std::string & line)
+{
+	std::vector<std::string> tokens = SplitString(line, ' ');
+
+	this->OBJIndices.push_back(ParseOBJIndex(tokens[1], &this->hasUVs, &this->hasNormals));
+	this->OBJIndices.push_back(ParseOBJIndex(tokens[2], &this->hasUVs, &this->hasNormals));
+	this->OBJIndices.push_back(ParseOBJIndex(tokens[3], &this->hasUVs, &this->hasNormals));
+
+	if ((int)tokens.size() > 4) {
+		this->OBJIndices.push_back(ParseOBJIndex(tokens[1], &this->hasUVs, &this->hasNormals));
+		this->OBJIndices.push_back(ParseOBJIndex(tokens[3], &this->hasUVs, &this->hasNormals));
+		this->OBJIndices.push_back(ParseOBJIndex(tokens[4], &this->hasUVs, &this->hasNormals));
+	}
+}
+
+OBJIndex
+OBJModel::ParseOBJIndex(const std::string & token, bool * hasUVs, bool * hasNormals)
+{
+	unsigned int tokenLength = token.length();
+	const char * tokenString = token.c_str();
+
+	unsigned int vertIndexStart = 0;
+	unsigned int vertIndexEnd = FindNextChar(vertIndexStart, tokenString, tokenLength, '/');
+
+	OBJIndex result;
+	result.vertexIndex = ParseOBJIndexValue(token, vertIndexStart, vertIndexEnd);
+	result.uvIndex = 0;
+	result.normalIndex = 0;
+
+	if (vertIndexEnd >= tokenLength)
+		return result;
+
+	vertIndexStart = vertIndexEnd + 1;
+	vertIndexEnd = FindNextChar(vertIndexStart, tokenString, tokenLength, '/');
+
+	result.uvIndex = ParseOBJIndexValue(token, vertIndexStart, vertIndexEnd);
+	*hasUVs = true;
+
+	if (vertIndexEnd >= tokenLength)
+		return result;
+
+	vertIndexStart = vertIndexEnd + 1;
+	vertIndexEnd = FindNextChar(vertIndexStart, tokenString, tokenLength, '/');
+
+	result.normalIndex = ParseOBJIndexValue(token, vertIndexStart, vertIndexEnd);
+	*hasNormals = true;
+
+	return result;
+}
+
+glm::vec3
+OBJModel::ParseOBJVec3(const std::string & line)
+{
+	unsigned int tokenLength = line.length();
+	const char * tokenString = line.c_str();
+
+	unsigned int vertIndexStart = 2;
+
+	while (vertIndexStart < tokenLength) {
+		if (tokenString[vertIndexStart] != ' ')
+			break;
+		vertIndexStart++;
+	}
+
+	unsigned int vertIndexEnd = FindNextChar(vertIndexStart, tokenString, tokenLength, ' ');
+
+	float x = ParseOBJFloatValue(line, vertIndexStart, vertIndexEnd);
+
+	vertIndexStart = vertIndexEnd + 1;
+	vertIndexEnd = FindNextChar(vertIndexStart, tokenString, tokenLength, ' ');
+
+	float y = ParseOBJFloatValue(line, vertIndexStart, vertIndexEnd);
+
+	vertIndexStart = vertIndexEnd + 1;
+	vertIndexEnd = FindNextChar(vertIndexStart, tokenString, tokenLength, ' ');
+
+	float z = ParseOBJFloatValue(line, vertIndexStart, vertIndexEnd);
+
+	return glm::vec3(x, y, z);
+
+	// glm::vec3(atof(tokens[1].c_str()), atof(tokens[2].c_str()), atof(tokens[3].c_str()))
+}
+
+glm::vec2
+OBJModel::ParseOBJVec2(const std::string & line)
+{
+	unsigned int tokenLength = line.length();
+	const char * tokenString = line.c_str();
+
+	unsigned int vertIndexStart = 3;
+
+	while (vertIndexStart < tokenLength) {
+		if (tokenString[vertIndexStart] != ' ')
+			break;
+		vertIndexStart++;
+	}
+
+	unsigned int vertIndexEnd = FindNextChar(vertIndexStart, tokenString, tokenLength, ' ');
+
+	float x = ParseOBJFloatValue(line, vertIndexStart, vertIndexEnd);
+
+	vertIndexStart = vertIndexEnd + 1;
+	vertIndexEnd = FindNextChar(vertIndexStart, tokenString, tokenLength, ' ');
+
+	float y = ParseOBJFloatValue(line, vertIndexStart, vertIndexEnd);
+
+	return glm::vec2(x, y);
+}
+
+static bool
+CompareOBJIndexPtr(const OBJIndex * a, const OBJIndex * b)
+{
+	return a->vertexIndex < b->vertexIndex;
+}
+
+static inline unsigned int
+FindNextChar(unsigned int start, const char * str, unsigned int length, char token)
+{
+	unsigned int result = start;
+	while (result < length) {
+		result++;
+		if (str[result] == token)
+			break;
+	}
+
+	return result;
+}
+
+static inline unsigned int
+ParseOBJIndexValue(const std::string & token, unsigned int start, unsigned int end)
+{
+	return atoi(token.substr(start, end - start).c_str()) - 1;
+}
+
+static inline float
+ParseOBJFloatValue(const std::string & token, unsigned int start, unsigned int end)
+{
+	return atof(token.substr(start, end - start).c_str());
+}
+
+static inline std::vector<std::string>
+SplitString(const std::string & s, char delim)
+{
+	std::vector<std::string> elems;
+
+	const char * cstr = s.c_str();
+	unsigned int strLength = s.length();
+	unsigned int start = 0;
+	unsigned int end = 0;
+
+	while (end <= strLength) {
+		while (end <= strLength) {
+			if (cstr[end] == delim)
+				break;
+			end++;
+		}
+
+		elems.push_back(s.substr(start, end - start));
+		start = end + 1;
+		end = start;
+	}
+
+	return elems;
+}