我按照this website的教程制作了一个简单的模型加载器。
所有的坐标都读得很好，但有一件事它没有超过是如何计算索引，但在一个进一步的教程found here称为VBO索引。虽然这似乎是一个很好的方法，但它计算的指数是错误的。
我在blender中创建了一个立方体，并导出为obj，我用一个obj加载器加载它，我以前从我的大学老师那里做过，索引读为0，1，2，3，4，（等等）. 35块买立方体而下面的代码的索引去0，1，2，3，. 16,17,0,18,3,19,4,6,20,7,9,21,10,12,22,13,15,23,16.
这是因为它找到了相似的顶点并将其推回索引，而实际上对于这个立方体来说不应该有任何相似的索引。
函数索引VBO慢
void Model::indexVBO_slow(
std::vector<glm::vec3>& in_vertices,
std::vector<glm::vec2>& in_uvs,
std::vector<glm::vec3>& in_normals,
std::vector<unsigned short>& out_indices,
std::vector<glm::vec3>& out_vertices,
std::vector<glm::vec2>& out_uvs,
std::vector<glm::vec3>& out_normals
) {
// For each input vertex
for (unsigned int i = 0; i < in_vertices.size(); i++) {
// Try to find a similar vertex in out_XXXX
unsigned short index;
bool found = getSimilarVertexIndex(in_vertices[i], in_uvs[i], in_normals[i], out_vertices, out_uvs, out_normals, index);
if (found) { // A similar vertex is already in the VBO, use it instead !
out_indices.push_back(index);
}
else { // If not, it needs to be added in the output data.
out_vertices.push_back(in_vertices[i]);
out_uvs.push_back(in_uvs[i]);
out_normals.push_back(in_normals[i]);
out_indices.push_back((unsigned short)out_vertices.size() - 1);
}
}
}我把从文件中读取的顶点、uv和法线传入vector 3s和vector 2的vector中。其他人叫出_作为空容器进去。
函数getSimilarVertexIndex
// Searches through all already-exported vertices
// for a similar one.
// Similar = same position + same UVs + same normal
bool Model::getSimilarVertexIndex(glm::vec3& in_vertex, glm::vec2& in_uv, glm::vec3& in_normal, std::vector<glm::vec3>& out_vertices, std::vector<glm::vec2>& out_uvs, std::vector<glm::vec3>& out_normals, unsigned short& result)
{
// Lame linear search
for (unsigned int i = 0; i < out_vertices.size(); i++)
{
if (
is_near(in_vertex.x, out_vertices[i].x) &&
is_near(in_vertex.y, out_vertices[i].y) &&
is_near(in_vertex.z, out_vertices[i].z) &&
is_near(in_uv.x, out_uvs[i].x) &&
is_near(in_uv.y, out_uvs[i].y) &&
is_near(in_normal.x, out_normals[i].x) &&
is_near(in_normal.y, out_normals[i].y) &&
is_near(in_normal.z, out_normals[i].z)
)
{
result = i;
return true;
}
}
// No other vertex could be used instead.
// Needs to be added to VBO
return false;
}函数is_near
bool Model::is_near(float v1, float v2) {
return fabs(v1 - v2) < 0.01f;
}填写EBO
// Fill EBO with indices
m_buffer->BindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_EBO); //gl bind buffer
m_buffer->FillBuffer(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLuint), &indices[0], GL_STATIC_DRAW); //gl buffer data我100%确定这不起作用的原因是我不完全理解从obj获取数据并将其转换为OpenGL索引之间的逻辑。我理解它检查是否已经找到了一些数据，这样它就可以重用一些索引数据，但不是if语句的细节。也许这是事实，我把它作为一个EBO和教程是做VBO索引。
解析器代码加VBO索引
std::vector <glm::vec3> m_vertices, m_normals;
std::vector <glm::vec2> m_uvs;
std::vector <unsigned int> vertexIndices, uvIndices, normalIndices;
std::vector<unsigned short> out_indices;
std::vector<glm::vec3> out_vertices;
std::vector<glm::vec2> out_uvs;
std::vector<glm::vec3> out_normals;
std::vector<glm::vec3> temp_vertices, temp_normals;
std::vector<glm::vec2> temp_uvs;
std::string temp_text = "";
FILE* file = fopen(filepath.c_str(), "r");
// Open File
if (!file)
{
TheDebug::Log("Impossible to openfile", ALERT);
return false;
}
// Read file until the end
while (1)
{
char lineHeader[128];
// read the first word of the line
int res = fscanf(file, "%s", lineHeader);
if (res == EOF)
{
break;
}
// Parse line header
int x = strcmp(lineHeader, "v");
if (strcmp(lineHeader, "v") == 0)
{
glm::vec3 vertex;
fscanf(file, "%f %f %f\n", &vertex.x, &vertex.y, &vertex.z);
temp_vertices.push_back(vertex);
}
// Scan for UVs
else if (strcmp(lineHeader, "vt") == 0)
{
glm::vec2 uv;
glm::vec2 uv2;
glm::vec2 uv3;
fscanf(file, "%f %f %f %f\n", &uv.x, &uv.y, &uv3.x, &uv2.y);
temp_uvs.push_back(uv);
}
// Scan for normals
else if (strcmp(lineHeader, "vn") == 0) {
glm::vec3 normal;
fscanf(file, "%f %f %f\n", &normal.x, &normal.y, &normal.z);
temp_normals.push_back(normal);
}
// Scan for faces
else if (strcmp(lineHeader, "f") == 0)
{
std::string vertex1, vertex2, vertex3;
unsigned int vertexIndex[4], uvIndex[4], normalIndex[4];
int matches = fscanf(file, "%d/%d/%d %d/%d/%d %d/%d/%d\n", &vertexIndex[0], &uvIndex[0], &normalIndex[0], &vertexIndex[1], &uvIndex[1], &normalIndex[1], &vertexIndex[2], &uvIndex[2], &normalIndex[2]);
if (matches != 9)
{
printf("File can't be read : ( Try exporting with other options\n");
fclose(file);
return false;
}
// Triangulated
if (matches == 9)
{
//Add 3 total vertices
m_totalVertices += 3;
vertexIndices.push_back(vertexIndex[0]);
vertexIndices.push_back(vertexIndex[1]);
vertexIndices.push_back(vertexIndex[2]);
uvIndices.push_back(uvIndex[0]);
uvIndices.push_back(uvIndex[1]);
uvIndices.push_back(uvIndex[2]);
normalIndices.push_back(normalIndex[0]);
normalIndices.push_back(normalIndex[1]);
normalIndices.push_back(normalIndex[2]);
}
}
}
// Go through each vertex of each triangle
for (unsigned int i = 0; i < vertexIndices.size(); i++)
{
unsigned int vertexIndex = vertexIndices[i];
unsigned int uvIndex = uvIndices[i];
unsigned int normalIndex = normalIndices[i];
glm::vec3 vertex = temp_vertices[vertexIndex - 1];
glm::vec2 uv = temp_uvs[uvIndex - 1];
glm::vec3 normal = temp_normals[normalIndex - 1];
m_normals.push_back(normal);
m_vertices.push_back(vertex);
m_uvs.push_back(uv);
}
fclose(file);
unsigned short result;
std::vector<GLuint> indices;
std::vector<glm::vec3> indexed_vertices;
std::vector<glm::vec2> indexed_uvs;
std::vector<glm::vec3> indexed_normals;
indexVBO(m_vertices, m_uvs, m_normals, indices, indexed_vertices, indexed_uvs, indexed_normals);
// After I fill buffers with the these indices.加载Cube的图片
- 请记住，问题是在计算指数，因为使用另一个模型加载器的指数是不同的，从0-35同时进行，而我的没有。
1条答案
按热度按时间zaqlnxep1#
经过漫长的4天测试，我发现我可以在for循环中将v3的向量转换为GL浮点数的向量，然后将所有向量相加，并为每个i添加索引。
这似乎至少在我使用的3个三角模型上工作，不知道这是否是最好的方法。