我正在尝试在Assimp中正确加载collada(dae)文件,但是法线似乎出了错。我想帮助您解决这个问题。我感觉这与我处理变换矩阵的方式有关。例如,下面是OpenGL应用程序加载obj文件的屏幕截图:
在上面的屏幕截图中,灯光位于x = 0和z = 0处的模型正上方。法线显示正确。加载dae文件时,得到以下信息:
灯光位置似乎来自-z侧。
这是我当前必须加载模型的代码:
processNode()
的aiMatrix4x4()
方法>void Model::loadModel(std::string filename)
{
Assimp::Importer importer;
const aiScene *scene = importer.ReadFile(filename, aiProcess_Triangulate | aiProcess_FlipUVs | aiProcess_CalcTangentSpace | aiProcess_GenBoundingBoxes);
if (!scene || !scene->mRootNode) {
std::cout << "ERROR::ASSIMP Could not load model: " << importer.GetErrorString() << std::endl;
}
else {
this->directory = filename.substr(0, filename.find_last_of('/'));
this->processNode(scene->mRootNode, scene, aiMatrix4x4());
}
}
processNode()
是一种递归方法,主要对node->mMeshes
进行迭代,然后乘以转换。void Model::processNode(aiNode* node, const aiScene* scene, aiMatrix4x4 transformation)
{
for (unsigned int i = 0; i < node->mNumMeshes; i++) {
aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];
// only apply transformation on meshs not entities such as lights or camera.
transformation *= node->mTransformation;
this->meshes.push_back(processMesh(mesh, scene, transformation));
}
for (unsigned int i = 0; i < node->mNumChildren; i++)
{
processNode(node->mChildren[i], scene, transformation);
}
}
processMesh()
处理收集所有网格数据(顶点,索引等)]Mesh Model::processMesh(aiMesh* mesh, const aiScene* scene, aiMatrix4x4 transformation)
{
glm::vec3 extents;
glm::vec3 origin;
std::vector<Vertex> vertices = this->vertices(mesh, extents, origin, transformation);
std::vector<unsigned int> indices = this->indices(mesh);
std::vector<Texture> textures = this->textures(mesh, scene);
return Mesh(
vertices,
indices,
textures,
extents,
origin,
mesh->mName
);
}
vertices()
方法以获取所有顶点。它通过转换矩阵。在这里,我将顶点与矩阵(transformation * mesh->mVertices[i];
)相乘。我有一种强烈的感觉,就是我不在这里做某事,而我正在错过某件事。std::vector<Vertex> Model::vertices(aiMesh* mesh, glm::vec3& extents, glm::vec3 &origin, aiMatrix4x4 transformation)
{
std::vector<Vertex> vertices;
for (unsigned int i = 0; i < mesh->mNumVertices; i++) {
Vertex vertex;
glm::vec3 vector3;
aiVector3D v = transformation * mesh->mVertices[i];
// Vertices
vector3.x = v.x;
vector3.y = v.y;
vector3.z = v.z;
vertex.position = vector3;
// Normals
if (mesh->mNormals) {
vector3.x = mesh->mNormals[i].x;
vector3.y = mesh->mNormals[i].y;
vector3.z = mesh->mNormals[i].z;
vertex.normal = vector3;
}
// Texture coordinates
if (mesh->mTextureCoords[0]) {
glm::vec2 vector2;
vector2.x = mesh->mTextureCoords[0][i].x;
vector2.y = mesh->mTextureCoords[0][i].y;
vertex.texCoord = vector2;
}
else {
vertex.texCoord = glm::vec2(0, 0);
}
if (mesh->mTangents) {
vector3.x = mesh->mTangents[i].x;
vector3.y = mesh->mTangents[i].y;
vector3.z = mesh->mTangents[i].z;
vertex.tangent = vector3;
}
// Bitangent
if (mesh->mBitangents) {
vector3.x = mesh->mBitangents[i].x;
vector3.y = mesh->mBitangents[i].y;
vector3.z = mesh->mBitangents[i].z;
vertex.bitangent = vector3;
}
vertices.push_back(vertex);
}
glm::vec3 min = glm::vec3(mesh->mAABB.mMin.x, mesh->mAABB.mMin.y, mesh->mAABB.mMin.z);
glm::vec3 max = glm::vec3(mesh->mAABB.mMax.x, mesh->mAABB.mMax.y, mesh->mAABB.mMax.z);
extents = (max - min) * 0.5f;
origin = glm::vec3((min.x + max.x) / 2.0f, (min.y + max.y) / 2.0f, (min.z + max.z) / 2.0f);
printf("%f,%f,%f\n", origin.x, origin.y, origin.z);
return vertices;
}
作为补充,如果有帮助,这是我在模型上使用的片段着色器:
#version 330 core out vec4 FragColor; in vec3 Normal; in vec3 FragPos; uniform vec3 lightPos; uniform vec3 viewPos; vec3 lightColor = vec3(1,1,1); vec3 objectColor = vec3(0.6, 0.6, 0.6); uniform float shininess = 32.0f; uniform vec3 material_specular = vec3(0.1f, 0.1f, 0.1f); uniform vec3 light_specular = vec3(0.5f, 0.5f, 0.5f); void main() { // ambient float ambientStrength = 0.2; vec3 ambient = ambientStrength * lightColor; // diffuse vec3 norm = normalize(Normal); vec3 lightDir = normalize(lightPos - FragPos); float diff = max(dot(norm, lightDir), 0.0); vec3 diffuse = diff * lightColor; // specular vec3 viewDir = normalize(viewPos - FragPos); vec3 reflectDir = reflect(-lightDir, norm); float spec = pow(max(dot(viewDir, reflectDir), 0.0), shininess); vec3 specular = light_specular * (spec * material_specular); vec3 result = (ambient + diffuse + specular) * objectColor; FragColor = vec4(result, 1.0); }
这里是顶点着色器:
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
out vec3 FragPos;
out vec3 Normal;
uniform mat4 projection;
uniform mat4 view;
uniform mat4 model;
uniform float scale;
void main()
{
FragPos = vec3(model * vec4(aPos, 1.0));
Normal = aNormal;
gl_Position = projection * view * vec4(FragPos, 1.0);
}
我正在尝试在Assimp中正确加载collada(dae)文件,但是法线似乎出了错。我想帮助您解决这个问题。我觉得这与我如何处理...
FragPos
是世界空间中的位置,因为它是由模型矩阵转换的顶点位置。 lightPos
和viewPos
似乎也位于世界空间中。因此,也必须将法线向量aNormal
从模型空间转换为世界空间。