How to get vertex data in OpenGL from an OBJ file using a GLM object loader?

Question

I'm using the following tutorial for drawing a mesh in OpenGL: https://www.d.umn.edu/~ddunham/cs5721f07/schedule/resources/lab_opengl07.html

At that site, there are links to the GLM source filesthat are used for loading an OBJ mesh. I am able to successfully draw a mesh using this technique. However, I need to be able to get the vertices of the mesh (say in a vector) to analyze and manipulate. How can this be done?

Answer 1

This should help (please refer to the provided header/source):

GLMmodel* model = glmReadOBJ(...);

int vertex_count = model->numvertices; // # of vertices in the mesh
float x0 = model->vertices[3 * 0 + 0]; // x coordinates of the 1st vertex 
float y0 = model->vertices[3 * 0 + 1]; // y coordinates of the 1st vertex
float z0 = model->vertices[3 * 0 + 2]; // z coordinates of the 1st vertex

float x1 = model->vertices[3 * 1 + 1]; // x coordinates of the 2nd vertex
...

int triangle_count = obj_model->numtriangles; // # of triangles in the mesh
const GLMtriangle& triangle0 = model->triangles[0]; // 1st triangle
int index0 = triangle0.vindices[0]; // index of the 1st vertex of the 1st triangle
...
const GLMtriangle& triangle1 = model->triangles[1]; // 2nd triangle
...