glm 旋转无法正常工作

Posted 2023-02-22

【中文标题】glm 旋转无法正常工作

【英文标题】：glm rotation not working properly

【发布时间】：2014-12-06 19:51:40

【问题描述】：

我正在尝试围绕 X 和 Y 轴旋转一个立方体。我不知道为什么它对这两个不起作用，它只在 Z 轴周围起作用。不工作是指立方体也在移动，并且没有在原地旋转。

我使用的相关代码是：

void rotateZ(float angle) 
        _modelMatrix = glm::rotate(_modelMatrix, -angle, glm::vec3(0,0,1));
    
    void rotateY(float angle) 
        _modelMatrix = glm::rotate(_modelMatrix, -angle, glm::vec3(0,1,0));
    
    void rotateX(float angle) 
        _modelMatrix = glm::rotate(_modelMatrix, -angle, glm::vec3(1,0,0));
    
    void translate_to_origin() 
        _modelMatrix = glm::translate(_modelMatrix, glm::vec3(-(_x + _n/2), -(_y +  _n/2), -(_z + _n/2)));
       
    void translate_to_position() 
        _modelMatrix = glm::translate(_modelMatrix, glm::vec3(_x + _n/2, _y + _n/2, _z + _n/2));
    
    void translate (float x, float y, float z) 
        _modelMatrix = glm::translate(_modelMatrix, glm::vec3(x, y, z));
    

    void create(float x, float y, float z, float n) 


                std::vector<MyVertexFormat>verts;
                std::vector<glm::uvec3>indx;


                verts.push_back(MyVertexFormat(x,   y,  z,  1,0,0));
                verts.push_back(MyVertexFormat(x + n,   y,  z,  1,0,0));
                verts.push_back(MyVertexFormat(x + n,   y,  z - n,  0,1,0));
                verts.push_back(MyVertexFormat(x,   y,  z - n,  0,0,1));

                verts.push_back(MyVertexFormat(x,   y + n,  z,  1,0,0));
                verts.push_back(MyVertexFormat(x + n,   y + n,  z,  1,0,0));
                verts.push_back(MyVertexFormat(x + n,   y + n,  z - n,  1,0,1));
                verts.push_back(MyVertexFormat(x,   y - n,  z - n,  1,1,1));


        indx.push_back(glm::uvec3(0,1,2));
                indx.push_back(glm::uvec3(2,3,0));

        indx.push_back(glm::uvec3(4,5,6));
                indx.push_back(glm::uvec3(6,7,4));


        indx.push_back(glm::uvec3(0,1,4));
                indx.push_back(glm::uvec3(4,5,1));


        indx.push_back(glm::uvec3(1,2,5));
                indx.push_back(glm::uvec3(5,6,2));


        indx.push_back(glm::uvec3(0,3,4));
                indx.push_back(glm::uvec3(4,7,3));


        indx.push_back(glm::uvec3(2,3,7));
                indx.push_back(glm::uvec3(7,6,2));


        //vao
                glGenVertexArrays(1, &mesh_vao);
                glBindVertexArray(mesh_vao);

                //vbo
                glGenBuffers(1, &mesh_vbo);
                glBindBuffer(GL_ARRAY_BUFFER, mesh_vbo);
                glBufferData(GL_ARRAY_BUFFER, sizeof(MyVertexFormat) * verts.size(), &verts[0], GL_STATIC_DRAW);

                //ibo
                glGenBuffers(1, &mesh_ibo);
                glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mesh_ibo);
                glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * indx.size() * 3, &indx[0], GL_STATIC_DRAW);

                int pipe = glGetAttribLocation(_glProgramShader, "in_position");
                glEnableVertexAttribArray(pipe);
                glVertexAttribPointer(pipe, 3, GL_FLOAT, GL_FALSE, sizeof(MyVertexFormat), (void*)0);

                pipe = glGetAttribLocation(_glProgramShader, "in_color");
                glEnableVertexAttribArray(pipe);
                glVertexAttribPointer(pipe, 3, GL_FLOAT, GL_FALSE, sizeof(MyVertexFormat), (void*)sizeof(glm::vec3));
                mesh_num_indices = indx.size() * 3;
    

旋转我使用的立方体：

cube->translate_to_position();
cube->rotateY(angle);
cube->translate_to_origin();

【问题讨论】：

我还没有研究整个东西，但是translate_to_origin()中使用的运算符看起来不一致。为什么你用- 表示x，而+ 表示y 和z？

对不起.. 这只是一个编辑错误。我编辑了帖子

顶点坐标也有些奇怪。部分是 ` + n` ，部分是 ` - n` 。例如对于 y 坐标，它使用所有 y、y + n 和 y - n。我不认为你会从中得到一个立方体。

【参考方案1】：

我解决了这个问题！我没有正确构建幼崽。正确的方法是

            verts.push_back(MyVertexFormat(x,   y,  z,  1,0,0));
            verts.push_back(MyVertexFormat(x + n,   y,  z,  1,0,0));
            verts.push_back(MyVertexFormat(x + n,   y,  z + n,  0,1,0));
            verts.push_back(MyVertexFormat(x,   y,  z + n,  0,0,1));

            verts.push_back(MyVertexFormat(x,   y + n,  z,  1,0,0));
            verts.push_back(MyVertexFormat(x + n,   y + n,  z,  1,0,0));
            verts.push_back(MyVertexFormat(x + n,   y + n,  z + n,  1,0,1));
            verts.push_back(MyVertexFormat(x,   y + n,  z + n,  1,1,1));