Render a scene with openGL

Question

I've to render a scene that include various mesh with openGL. the meshes are defined like this:

struct Mesh {
frame3f         frame;      // frame
vector<vec3f>   pos;        // vertex position
vector<vec3f>   norm;       // vertex normal
vector<vec2f>   texcoord;   // vertex texcture coordinates
vector<vec3i>   triangle;   // triangle
vector<vec4i>   quad;       // quad
Material*       mat;        // material}

the mesh can be made of triangles and quads, I try to render the vertex with this code:

for (auto mesh : scene->meshes)
{
    // bind material kd, ks, n
    glVertexAttrib3f(material_kd_loc, mesh->mat->kd.x, mesh->mat->kd.y, mesh->mat->kd.z);
    glVertexAttrib3f(material_ks_loc, mesh->mat->ks.x, mesh->mat->ks.y, mesh->mat->ks.z);
    glVertexAttrib1f(material_n_loc, mesh->mat->n);

    // bind mesh frame - use frame_to_matrix
    mat4f mesh_mat = frame_to_matrix(mesh->frame);
    glUniformMatrix4fv(mesh_frame_loc, 1, GL_TRUE, &mesh_mat[0][0]);

    // enable vertex attributes arrays
    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);

    //and set up pointers to the mesh data
    glVertexAttribPointer(vertex_pos_loc, mesh->pos.size(), GL_FLOAT, GL_FALSE, 0, mesh->pos.data());
    glVertexAttribPointer(vertex_norm_loc, mesh->norm.size(), GL_FLOAT, GL_TRUE, 0, mesh->norm.data());

    // draw triangles and quads
    if (mesh->triangle.size() != 0){

        glDrawElements(GL_TRIANGLES, mesh->pos.size(), GL_UNSIGNED_INT, mesh->triangle.data());
    }
    if (mesh->quad.size() != 0){
        glDrawElements(GL_QUADS, mesh->pos.size(), GL_UNSIGNED_INT, mesh->quad.data());

    }
    // disable vertex attribute arrays
    glDisableVertexAttribArray(0);
    glDisableVertexAttribArray(1);
}

} this is what i draw (don't care about colors as i don't calculate them yet)

this is what i should see if my code is correct

anyone as an idea of where is the error?

Answer 1

look like the opengl function wants the total number of vertecx to be written and not just the number of different vertex. so:

glDrawElements(GL_TRIANGLES, mesh->triangle.size()*3, GL_UNSIGNED_INT, mesh->triangle.data());
glDrawElements(GL_QUADS, mesh->quad.size()*4, GL_UNSIGNED_INT, mesh->quad.data());

Answer 2

glDrawElements(GL_TRIANGLES, mesh->pos.size(), GL_UNSIGNED_INT, mesh->triangle.data());
glDrawElements(GL_QUADS, mesh->quad.size(), GL_UNSIGNED_INT, mesh->quad.data());

Take a look at second argument on both calls. It is incorrect for quads.

glVertexAttribPointer(vertex_pos_loc, mesh->pos.size(), GL_FLOAT, GL_FALSE, 0, mesh->pos.data());

Is incorrect too - second parameter is number of components per vertex, not size of array.