我在c中编写了一个简单的obj解析器,它加载了顶点,索引和纹理坐标(这就是我需要的所有数据) .
这是功能:
Model* ModelLoader::loadFromOBJ(string objFile, ShaderProgram *shader, GLuint texture)
{
fstream file;
file.open(objFile);
if (!file.is_open())
{
cout << "ModelLoader: " << objFile << " was not found";
return NULL;
}
int vertexCount = 0;
int indexCount = 0;
vector<Vector3> vertices;
vector<Vector2> textureCoordinates;
vector<Vector2> textureCoordinatesFinal;
vector<unsigned int> vertexIndices;
vector<unsigned int> textureIndices;
string line;
while (getline(file, line))
{
vector<string> splitLine = Common::splitString(line, ' ');
// v - vertex
if (splitLine[0] == "v")
{
Vector3 vertex(stof(splitLine[1]), stof(splitLine[2]), stof(splitLine[3]));
vertices.push_back(vertex);
vertexCount++;
}
// vt - texture coordinate
else if (splitLine[0] == "vt")
{
Vector2 textureCoordinate(stof(splitLine[1]), 1 - stof(splitLine[2]));
textureCoordinates.push_back(textureCoordinate);
}
// f - face
else if (splitLine[0] == "f")
{
vector<string> faceSplit1 = Common::splitString(splitLine[1], '/');
vector<string> faceSplit2 = Common::splitString(splitLine[2], '/');
vector<string> faceSplit3 = Common::splitString(splitLine[3], '/');
unsigned int vi1 = stoi(faceSplit1[0]) - 1;
unsigned int vi2 = stoi(faceSplit2[0]) - 1;
unsigned int vi3 = stoi(faceSplit3[0]) - 1;
unsigned int ti1 = stoi(faceSplit1[1]) - 1;
unsigned int ti2 = stoi(faceSplit2[1]) - 1;
unsigned int ti3 = stoi(faceSplit3[1]) - 1;
vertexIndices.push_back(vi1);
vertexIndices.push_back(vi2);
vertexIndices.push_back(vi3);
textureIndices.push_back(ti1);
textureIndices.push_back(ti2);
textureIndices.push_back(ti3);
indexCount += 3;
}
}
// rearanging textureCoordinates into textureCoordinatesFinal based on textureIndices
for (int i = 0; i < indexCount; i++)
textureCoordinatesFinal.push_back(textureCoordinates[textureIndices[i]]);
Model *result = new Model(shader, vertexCount, &vertices[0], NULL, texture, indexCount, &textureCoordinatesFinal[0], &vertexIndices[0]);
models.push_back(result);
return result;
}
如您所见,我考虑了1 - texCoord.y(因为blender和opengl使用不同的纹理坐标系) . 我还根据while循环后的纹理索引排列纹理坐标 .
但是,我尝试渲染的模型的纹理搞砸了 . 这是一个例子:
纹理搞砸了
我甚至用一个立方体尝试了它,我在搅拌机中打开了自己,并应用了一个非常简单的砖纹理 . 在1或2个面中,纹理很好并且正常工作,然后在其他一些面上,其中一个tringle具有正确的纹理,而其他的则出现拉伸(与上图中相同) .
1 回答
要定义网格,只有一个索引列表可以索引顶点属性 . 顶点属性(在您的情况下是顶点和纹理坐标)形成一个记录集,由这些索引引用 .
这导致每个顶点坐标可能在列表中出现多次,并且每个纹理坐标可能在列表中出现多次 . 但顶点和纹理坐标的每个组合都是唯一的 .
取
vertexIndices
和textureIndices
创建唯一的顶点对和纹理坐标对(verticesFinal
,textureCoordinatesFinal
) .创建新的
attribute_indices
,索引对 .使用临时容器
attribute_pairs
来管理唯一对并识别其索引:请注意,顶点坐标的数量(
verticesFinal.size()
)等于纹理坐标的数量(textureCoordinatesFinal.size()
) . 但指数(attribute_indices.size()
)的数量完全不同 .