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我有一个带有多个网格的 .obj 模型。我想为每个网格创建一个 vao。然后渲染所有的东西。

为此，我想创建一个 vao 指针，根据模型中的网格数量更改其大小。

我使用 assimp 为模型充电。

没有编译问题，但执行此程序时程序崩溃。

      glBindVertexArray(modele_multvao[z]);
      glDrawArrays(GL_TRIANGLES, 0, modele_multcount[z]);

知道我的程序出了什么问题？（我对openGL有点陌生）

我的代码：

GLuint *modele_vao;
int *point_count;
int number_of_mesh;

bool load_mesh(const char* file_name, GLuint* vao, int* point_count,int* num_mesh) {
/* load file with assimp and print some stats */
const aiScene* scene = aiImportFile(file_name, aiProcess_Triangulate);
if (!scene) {
    std::wcout <<"ERROR: reading mesh: "<< file_name << std::endl;
    std::wcout << aiGetErrorString() << std::endl;
    return false;
}
std::wcout << "mesh import succeeded" << std::endl;
std::wcout << scene->mNumAnimations << " animations" << std::endl;
std::wcout << scene->mNumCameras << " cameras" << std::endl;
std::wcout << scene->mNumLights << " lights" << std::endl;
std::wcout << scene->mNumMaterials << " materials" << std::endl;
std::wcout << scene->mNumMeshes << " meshes" << std::endl;
std::wcout << scene->mNumTextures << " textures" << std::endl;

num_mesh=scene->mNumMeshes;
vao = new GLuint[scene->mNumMeshes];
point_count=new int[scene->mNumMeshes];

int i=0;
for(i=1;i<=(scene->mNumMeshes);i++)
{
    /* get mesh n°i in file  */
    const aiMesh* mesh = scene->mMeshes[i-1];
    std::wcout << "vertices in mesh :" << mesh->mNumVertices<< std::endl;

    /* pass back number of vertex points in mesh */
    *point_count = mesh->mNumVertices;

    /* generate a VAO, using the pass-by-reference parameter that we give to the
    function */

    glGenVertexArrays(scene->mNumMeshes, vao);
    glBindVertexArray(vao[i-1]);

    /* we really need to copy out all the data from AssImp's funny little data
    structures into pure contiguous arrays before we copy it into data buffers
    because assimp's texture coordinates are not really contiguous in memory.
    i allocate some dynamic memory to do this. */
    GLfloat* points = NULL; // array of vertex points
    GLfloat* normals = NULL; // array of vertex normals
    GLfloat* texcoords = NULL; // array of texture coordinates
    if (mesh->HasPositions()) {
        points = (GLfloat*)malloc(*point_count * 3 * sizeof (GLfloat));
        for (int i = 0; i < *point_count; i++) {
            const aiVector3D* vp = &(mesh->mVertices[i]);
            points[i * 3] = (GLfloat)vp->x;
            points[i * 3 + 1] = (GLfloat)vp->y;
            points[i * 3 + 2] = (GLfloat)vp->z;
        }
    }
    if (mesh->HasNormals()) {
        normals = (GLfloat*)malloc(*point_count * 3 * sizeof (GLfloat));
        for (int i = 0; i < *point_count; i++) {
            const aiVector3D* vn = &(mesh->mNormals[i]);
            normals[i * 3] = (GLfloat)vn->x;
            normals[i * 3 + 1] = (GLfloat)vn->y;
            normals[i * 3 + 2] = (GLfloat)vn->z;
        }
    }
    if (mesh->HasTextureCoords(0)) {
        texcoords = (GLfloat*)malloc(*point_count * 2 * sizeof (GLfloat));
        for (int i = 0; i < *point_count; i++) {
            const aiVector3D* vt = &(mesh->mTextureCoords[0][i]);
            texcoords[i * 2] = (GLfloat)vt->x;
            texcoords[i * 2 + 1] = (GLfloat)vt->y;
        }
    }

    /* copy mesh data into VBOs */
    if (mesh->HasPositions()) {
        GLuint vbo_pos;
        glGenBuffers(1, &vbo_pos);
        glBindBuffer(GL_ARRAY_BUFFER, vbo_pos);
        glBufferData(
            GL_ARRAY_BUFFER,
            3 * *point_count * sizeof (GLfloat),
            points,
            GL_DYNAMIC_DRAW
            );
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
        glEnableVertexAttribArray(0);
        free(points); // free our temporary memory
    }
    if (mesh->HasNormals()) {
        GLuint vbo_norm;
        glGenBuffers(1, &vbo_norm);
        glBindBuffer(GL_ARRAY_BUFFER, vbo_norm);
        glBufferData(
            GL_ARRAY_BUFFER,
            3 * *point_count * sizeof (GLfloat),
            normals,
            GL_DYNAMIC_DRAW
            );
        glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, 0, NULL);
        glEnableVertexAttribArray(2);
        free(normals); // free our temporary memory
    }
    if (mesh->HasTextureCoords(0)) {
        GLuint vbo_tex;
        glGenBuffers(1, &vbo_tex);
        glBindBuffer(GL_ARRAY_BUFFER, vbo_tex);
        glBufferData(
            GL_ARRAY_BUFFER,
            2 * *point_count * sizeof (GLfloat),
            texcoords,
            GL_DYNAMIC_DRAW
            );
        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, NULL);
        glEnableVertexAttribArray(1);
        free(texcoords); // free our temporary memory
    }
    if (mesh->HasTangentsAndBitangents()) {
        // NB: could store/print tangents here
    }
}

/* free assimp's copy of memory */
aiReleaseImport(scene);
std::wcout << "mesh loaded" << std::endl;

return true;
}



int main()
{
    load_mesh("somewhere", modele_vao, point_count, &num_of_mesh)

    [...]

    while(1){

        [...]

        for(z=0;z<num_of_mesh;z++){
            glBindVertexArray(modele_vao[z]);
            glDrawArrays(GL_TRIANGLES, 0, modele_count[z]);
        }

    }
}
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1 回答 1

0

您正在将newed 数组分配给局部变量。函数返回后，这块内存就丢失了。

它应该是这样的：

bool load_mesh(const char* file_name, GLuint** _vao, int** _point_count,int* num_mesh)

（注意**两个参数，_为了举例）

接着，：

GLuint *vao = new GLuint[scene->mNumMeshes];
*_vao = vao;

第二个参数也是如此。

num_mesh是一个指针，但是您正在为其分配整数（并且它是本地的，因此再次丢失了值）。应该是*num_mesh = scene->mNumMeshes;。

另一件事是您glGenVertexArrays在循环中使用 - 它应该只使用一次；在每次迭代中，您都会丢失以前的数据。

目前尚不清楚一旦不再需要顶点数组，您将如何删除它们，因为调用方不知道这些值是什么。

于 2014-07-07T10:52:40.977 回答